Hydroquinone usage: Hydroquinone Skin Bleaching Topical: Uses, Side Effects, Interactions, Pictures, Warnings & Dosing
Hydroquinone | DermNet NZ
Authors: Vanessa Ngan, Staff Writer, 2005; Updated: Dr Ian Coulson, Consultant Dermatologist, East Lancashire NHS Trust, Lancashire, UK. Copy edited by Gus Mitchell. September 2021.
What is hydroquinone?
Hydroquinone is a skin-lightening agent used topically for the treatment of hyperpigmentation.
Who uses hydroquinone?
Hydroquinone is most commonly used in bleaching creams by patients aged 13 years and over with a dark skin type. It can be used, often in combination with other medications, to treat:
Hydroquinone may also be used as a pretreatment before fractional laser therapy or chemical peels.
Skin conditions that may be treated with hydroquinone
What are the contraindications with hydroquinone?
Hydroquinone should not be used by individuals allergic to hydroquinone or any of the excipients in the formulation such as the preservative metabisulphite. [see Contact allergy to preservatives]
Tell me more about hydroquinone.
Hydroquinone is used in a cream or lotion formulation in a concentration of 1-5%. It is often found in a combination formulation with other skin lightening agents such as topical retinoids (to increase efficiency) and low potency topical steroids (to reduce irritancy).
In New Zealand and many other countries, hydroquinone is only available on prescription, and may need to be compounded by the pharmacist.
Hydroquinone must be distinguished from monobenzyl ether of hydroquinone which can cause irreversible pigment loss. [see Depigmentation therapy for vitiligo]
Mechanism of action of hydroquinone
Hydroquinone lightens epidermal, but not dermal, pigmentation by reducing the production of new melanin:
- Reversible inhibition of tyrosinase, an enzyme involved in converting L3,4-diphenylalanine to the skin pigment melanin
- Selective damage to melanocytes and melanosomes.
How to use hydroquinone
Hydroquinone is applied topically just to the hyperpigmented skin only, twice daily for 3 months, after which time many patients maintain their improvement by using it twice each week. If there has been no benefit after 3 months of treatment, then the hydroquinone should be stopped. Management of the underlying cause of the hyperpigmentation is also recommended.
When initiating hydroquinone treatment, it is advisable to:
- Start with a test area about 1 cm in diameter. If there is no irritation or redness within 24 hours, the cream can be used more widely on the affected areas.
- Apply a thin film initially daily and if there is no irritation after one week, the application frequency can be increased to twice a day.
- Do not apply close to the eyes or mouth.
- Do not use any other topical medication, particularly benzoyl peroxide.
- Wait for 10 minutes before applying sunscreen or cosmetics over the hydroquinone.
- Treatment should be discontinued if undue redness, scaling, itch, or weeping occurs.
What are the benefits of hydroquinone?
Hydroquinone is particularly effective for the treatment of postinflammatory hyperpigmentation which is unlikely to recur provided the underlying inflammatory dermatosis is also controlled.
In melasma, 70% of sufferers notice clearance or reduction in pigmentation with twice daily hydroquinone used for three months. This improvement can be maintained in 50% of individuals with twice weekly application.
Response of melasma after three months of hydroquinone
What are the disadvantages of hydroquinone?
Hydroquinone does not treat pigmentation in the dermis.
Melasma can be resistant to treatment and usually requires combination therapy and multiple therapeutic approaches, of which hydroquinone is one component.
What are the side effects and risks of hydroquinone?
Hydroquinone can cause mild irritant contact dermatitis when used in concentrations above 4%. A short drug holiday and/or application of a topical steroid will usually settle the reaction.
Commercial formulations of hydroquinone contain the preservative metabisulphite, which can cause an allergic reaction.
Concerns have been raised about the safety of hydroquinone in Europe, Japan, and the USA due to:
- High dose oral hydroquinone causing cancer in rats, however after 50 years of topical use there have been no cases of cancer reported in humans
- Exogenous ochronosis due to topical hydroquinone used in high concentrations, multiple times per day, for years.
Other reported cutaneous adverse effects of hydroquinone include:
The safety of topical hydroquinone has not been established in pregnancy and lactation.
Nail pigmentation due to hydroquinone use
- Chandra M, Levitt J, Pensabene CA. Hydroquinone therapy for post-inflammatory hyperpigmentation secondary to acne: not just prescribable by dermatologists. Acta Derm Venereol. 2012;92(3):232–5. doi:10.2340/00015555-1225. Journal
- McKesey J, Tovar-Garza A, Pandya AG. Melasma treatment: an evidence-based review. Am J Clin Dermatol. 2020;21(2):173–225. doi:10.1007/s40257-019-00488-w. PubMed
- Saade DS, Maymone MBC, De La Garza H, Secemsky EA, Kennedy KF, Vashi NA. Trends in use of prescription skin lightening creams. Int J Environ Res Public Health. 2021;18(11):5650. doi:10.3390/ijerph28115650. Journal
- Schwartz C, Jan A, Zito PM. Hydroquinone. In: StatPearls. Treasure Island (FL): StatPearls Publishing; May 10, 2021. PubMed
- Sofen B, Prado G, Emer J. Melasma and post inflammatory hyperpigmentation: management update and expert opinion. Skin Therapy Lett. 2016;21(1):1–7. Journal
- Tse TW. Hydroquinone for skin lightening: safety profile, duration of use and when should we stop?. J Dermatolog Treat. 2010;21(5):272–5. doi:10.3109/09546630903341945. PubMed
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The Dos and Don’ts of Hydroquinone | Expert Tips
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Hydroquinone is the LeBron James of skin care. The skin lightener is as controversial as it is effective. When incorporated into your complexion regimen properly, hydroquinone decreases the production of melanin by inhibiting tyrosinase, an enzyme needed for melanin production, to decrease the appearance of hyperpigmentation. Because of this, many people consider it to be a skin-bleaching ingredient. According to Miami-based board-certified dermatologist Roberta Del Campo, it should be considered a “color blender” instead.
Things can go wrong (namely, a rare, unwanted side effect called exogenous ochronosis, “which is a paradoxical darkening of the treated skin,” Louisiana-based board-certified dermatologist Mamina Turegano tells Allure) if you don’t meticulously follow the dos and don’ts of hydroquinone, though.
Plus, the ingredient has been banned in Europe since 2001 on account of studies finding evidence of carcinogenicity in rodents when hydroquinone was orally administered. The U.S. Food and Drug Administration (FDA) took this into account and still deemed hydroquinone safe for topical application because not enough clear evidence of the risk outweighing the benefits exists. Dermatologists also are still willing to prescribe it to their patients.
Needless to say, we felt compelled to ask board-certified dermatologists to walk us through exactly what you need to do with the melasma remedy for it to be a safe, beneficial part of your skin-care routine.
DO consult your dermatologist first
Before implementing hydroquinone into your lineup, ask your dermatologist if it’s truly right for your skin tone and complexion concerns. Although it is suitable for all skin types, Turegano is cautious when recommending the ingredient to those with dry and sensitive skin because of the irritation it can cause. She’s also wary of those with deeper skin tones incorporating hydroquinone into their skin-care routines because the risk of exogenous ochronosis is higher than those with fairer complexions. Hydro isn’t off the table in these cases, but caution and close monitoring is needed.
DON’T use hydroquinone for too long
A major key to hydroquinone is short-term use. You can slather it on twice daily for at least six weeks (and no more than six months). After one to three months, you should start to see your hyperpigmentation fade away. At the three-month mark, you should set it aside. “Once you have achieved your desired results, stop using hydroquinone daily and only use it if the hyperpigmentation reappears,” says Aegean Chan, a board-certified dermatologist based in Santa Barbara, California.
DO wear (and reapply) sunscreen daily
Although sun protection is a given no matter what you’re putting on your face, it’s an essential worth stressing. Layering on ample sunscreen and diligently protecting your skin from UV exposure yields the best results with hydroquinone, Chan says.
DON’T mix hydroquinone with these ingredients
Turegano and Chan both agree hydroquinone does not play well with benzoyl peroxide, hydrogen peroxide, or other peroxide products. Not only will pairing them cause irritation and dryness, but it can also temporarily stain your skin.
Dermatologists Share the Right Way to Use Hydroquinone for Best Results
Beauty Insider posted “Dermatologists Share the Right Way to Use Hydroquinone for Best Results“, which features Visha Skincare founder, Dr. Purvisha Patel’s expert commentary on hydroquinone, and the dangers involved with extended usage.
Many women use lightening creams to fade freckles, acne marks, or other dark spots. More often than not, the key ingredient in hydroquinone. It’s one of the most potent treatments for hyperpigmentation, BUT it’s also controversial. In this guide to hydroquinone cream Singapore guide , you’ll find out how it works and how to use it safely.
What is hydroquinone, and how does it work?
“Hydroquinone is a topical skin treatment for melasma, freckles, age and sun spots, and even acne scars,” says cosmetic and plastic surgeon David Shafer. “Used in combination with other acne products such as Retin-A, hydroquinone can help dramatically improve skin complexion.”
Hydroquinone lightens the skin by supressing melanocytes, the skin cells that produce melanin.
Melanin is the pigment that gives our skin and hair its colour. Sometimes, our skin produces too much melanin, because of sun exposure, inflammation, hormonal changes, or ageing. Hydroquinone slows down melanin production, allowing existing spots to fade while preventing new ones from forming.
However, it can take several weeks for you to see the results. “Hydroquinone creams work at the cellular level to reduce the production of pigment,” Shafer explains, so you need to allow the skin to shed old cells and produce new ones.
Who can benefit from using hydroquinine cream?
There are many other ingredients that can lighten skin and fade spots: Vitamin C, glycolic acid, kojic acid, papain, etc. So when should you consider getting a hydroquinine?
“If you only have occasional or very light marks left by breakouts, you can just use a mild brightening wash and dark spot treatments, and a high SPF sunscreen,” says dermatologist Sharon Garcia. Use hydroquinone for more stubborn blemishes: marks that haven’t faded after several months, or recurring or persistent pigmentation.
“Hydroquinone is considered the topical gold standard in dermatology for reducing hyperpigmentation.”
Ee Ting Ng, cosmetic chemist
Dermatologists often use hydroquinone to treat melasma, a skin condition where dark patches appear on the forehead, cheeks and upper lip. While often genetic, melasma is triggered by sun exposure and hormonal changes like pregnancy, birth control pills, or hormone replacement therapy.
Hydroquinone is also effective for evening out the skin tone. It can treat discoloration or dark patches on your forehead or neck, so your skin looks brighter, fairer and blemish-free.
Is hydroquinone safe?
In 1982, the US FDA cleared hydroquinone as safe and effective for the treatment of hyperpigmentation.
However, several years later, some hydroquinone creams were pulled out of the market after their products were found to contain mercury. This caused public concern, and led to often exaggerated reports that said hydroquinone was toxic, dangerous or “the equivalent of a paint stripper of the skin.”
Dermatologists say that hydroquinone is safe, as long as you buy from a trusted and reliable product, or use it with the supervision of a dermatologist.
“Hydroquinone can irritate dry or sensitive skin, especially in high concentrations or if used with other skincare products that contain acids or physical exfoliants,” says dermatologist Harvey Ng.
Dr. Purvisha Patel also cautions against using hydroquinone for a long time. “There’s also a phenomenon called ochronosis, or increased pigmentation/darkening of the skin that is caused by hydroquinone in high concentrations and with long-term use,” she explains. “It is safe to use in 2% to 4% formulations twice a day for 12 weeks max. Then skin then needs a break from the chemical.”
Some experts also believe that hydroquinone works better on fairer skin tones. There is some research that the ingredient may worsen hyperpigmentation in darker skin tones. If you have medium to dark skin, talk to your dermatologist before using any hydroquinone cream.
Kinds of Hydroquinone Cream Singapore
Over the counter creams
These products typically combine hydroquinone with other skin-lightening ingredients. To avoid skin reactions, start with 2% concentration. Temporarily stop using exfoliators and facial brushes, or other products that contain acids like AHAs/BHAs or Vitamin C. Give your skin time to adjust to the ingredient. (You can start using these again when you know that you’re not sensitive to hydroquinone.)
Dermatologist Richard Bottiglione also recommends starting with a hydroquinone spot treatment. “Most people don’t need it all over the skin, just in particular areas. You should use it in the areas with hyperpigmentation.” If you tend to be sensitive, he suggests using it on alternating days.
When you know that your hydroquinone product works well with your skin, add a glycolic cleanser to your skincare routine. “Over the years I have never found a more effective treatment for unwanted pigmentation than glycolic acid and hydroquinone,” says Dr. Bottiglione.
Dermatologists also say that you need to use sunscreen with SPF 30 whenever you use any skin lightening cream. “I even recommend using your hydroquinone at night, to avoid any sun sensitivity,” says Dr. Patel.
Prescription hydroquinone creams
Stronger hydroquinone creams with higher than 2% concentration require a prescription. Beware of any over-the-counter product that contains higher dosages, or using a prescription cream without consulting a dermatologist. You risk irritating your skin, and this will actually cause inflammation that worsens hyperpigmentation.
Dermatologists can also check your skin condition to know the best treatment for you: the right concentration of ingredients, and how long you need to use it. They may also combine hydroquinone creams with other treatments, so you achieve faster results.
Safe Hydroquinone Cream Singapore treatments
Find the nearest dermatologist or skin clinic with Beauty Insider Guide. It lists Singapore clinics and their locations and contact numbers, and lets you filter results according to the treatment you’re looking for.
Read the full article
Hydroquinone – StatPearls – NCBI Bookshelf
Continuing Education Activity
Hydroquinone cream is the standard depigmentation or skin lightening agent. Clinically it is used to treat areas of dyschromia, such as in melasma, chloasma, solar lentigines, freckles, and post-inflammatory hyperpigmentation. This activity outlines the indications, mechanism of action, methods of administration, important adverse effects, contraindications, and monitoring of hydroquinone, so providers can direct patient therapy to optimal outcomes in conditions where it is indicated.
Outline the indications for using hydroquinone therapy.
Describe the mechanism of action of hydroquinone.
Summarize the potential adverse events associated with hydroquinone.
Review interprofessional team strategies for improving care coordination and communication to advance improved outcomes using hydroquinone when indicated.
Access free multiple choice questions on this topic.
Hydroquinone cream is the standard depigmentation or skin lightening agent. Clinically it is used to treat areas of dyschromia, such as in:
Its most common use is in patients with post-inflammatory hyperpigmentation and melasma.
Postinflammatory hyperpigmentation results from cutaneous inflammation, causing increased melanin production. Common causes of postinflammatory hyperpigmentation are acne vulgaris, eczematous dermatoses, contact dermatitis, psoriasis, lichen planus, and burns. The most common cause of hyperpigmentation results from photodamage from sunlight exposure. Inflammation increases the release and oxidation of arachidonic acid to prostaglandins and leukotrienes, resulting in increased melanin production. Hydroquinone is used to treat postinflammatory hyperpigmentation along with photoprotection. Improvement with hydroquinone occurs over several weeks to months.
Melasma is an acquired hyperpigmentation condition and presents on sun-exposed areas of the face, commonly the forehead, cheeks, and chin. It presents as symmetrically distributed pigmented macules and patches. Factors that play a role in the pathogenesis of melasma are darker skin, UV radiation, hormones, genetics, and antiepileptic medications. Exposure to UV radiation is the main factor in pathogenesis as UV radiation increases alpha-melanocyte-stimulating hormone and adrenocorticotropic hormone levels, which increases the proliferation of melanocytes. Also, at the dermal layer, increased expression of stem cells of fibroblasts and tyrosine kinase receptor c-kit is present in melasma lesions. Also noted in lesions are upregulation of vascular endothelial growth factor (VEGF), Wnt, and reactive oxygen species seen after UV-induced dermal inflammation. Vascularization and melanocyte hyperreactivity results from this UV-induced inflammation leading to increased melanin production and hyperpigmentation. Patients who are pregnant or use oral contraceptives are also at risk because the expression of estrogen receptors seems to rise in melasma lesions as well. Estrogen also induces the release of melanocyte-stimulating hormone (MSH), which stimulates tyrosinase leading to increased melanin production. For this reason, melasma occurs more frequently in females vs. males. Treatment is similar to postinflammatory hyperpigmentation, with photoprotection and hydroquinone being the first line.
Photoprotection is a significant key in maximal benefit from hydroquinone use. Melanocytes become stimulated from UVB, UVA, and even visible light leading to pigmentation. Therefore, broad-spectrum sunscreens are a recommended strategy.
Hydroquinone is not FDA approved due to its unknown safety profile. It is banned in the EU, Australia, and Japan.
Mechanism of Action
Hydroquinone acts as a skin depigmentation agent by inhibiting melanin synthesis. It inhibits the conversion of L-3,4- dihydroxyphenylalanine (L-DOPA) to melanin by inhibiting tyrosinase due to its structural similarity to an analog of melanin precursors.
The Pathway of Melanin Synthesis
Hydroxylation of L-phenylalanine to L-tyrosine
Tyrosinase hydroxylates L-tyrosine to 3,4 L-dihydroxyphenylalanine (L-DOPA)
L-DOPA oxidized to dopaquinone
Production of eumelanin and pheomelanin resulting in black to brown and yellow to red color of skin
Hydroquinone is only used topically as a depigmentation agent. A thin layer is applied with fingertips and rubbed into the face (or other affected areas) 1 to 2 times a day for 3 to 6 months. If there are no results after 2 to 3 months, hydroquinone should be discontinued. It is essential to evenly apply hydroquinone over the entire face to prevent uneven pigmentation and use concurrently with sunscreen to protect from damaging UV light, which increases pigmentation. Physicians recommended stopping treatment after this time for a few months before restarting to decrease the risk of side effects. It can also be applied during weekends only or three times a week for more extended maintenance therapy with minimal complications.
Hydroquinone is available in 2% over the counter or as 4% prescribed. It comes in the following dose forms: cream, emulsion, gel, or solution.
Multiple studies have shown that maximum results occur when using hydroquinone as a combination therapy with a retinoid and corticosteroid. The most widely used triple combination cream is composed of hydroquinone 4%, tretinoin 0. 05%, and fluocinolone acetonide 0.01%. Use in combination with other agents requires a prescription by a dermatologist.
Results vary among each patient.
About 35% to 45% of hydroquinone is absorbed systemically after topical use.
Adverse Effects Include
Allergic contact dermatitis
Rarely ochronosis – ochronosis is a blue-black or gray-blue discoloration; it is rare and more commonly seen in patients that use a high concentration of hydroquinone for a long period on large areas of the body.
Studies also suggest that hydroquinone can falsely elevate capillary glucose when measured with a glucometer.
There has been no confirmation regarding concerns that hydroquinone cream is carcinogenic either in clinical practice or human research.
Pregnancy Category C
About 35 to 45% of the topical hydroquinone dose is absorbed systemically. Current studies have not shown an increased risk of malformations or adverse effects in pregnant women, but it is recommended to minimize exposure due to the substantial absorption. The safety of breastfeeding mothers and children remains unestablished, and as such, breastfeeding females should avoid this drug.
Monitor for any hypersensitivity or long-term irritation, in which case the medication should be discontinued. Also, in rare cases, ochronosis develops; the patient should stop using hydroquinone and consult a clinician.
No significant toxicity has been found with the topical use of the hydroquinone cream.
Some studies report malignancies in animals treated for an extended period with large oral doses.
Hydroquinone in the Environment
In the environment, hydroquinone is a chemical and can be toxic in human and industrial activities by promoting the generation of reactive oxygen species, oxidative stress, and hence the potential for DNA damage. It is a major benzene metabolite and is known to be hepatotoxic and carcinogenic in these settings. Some studies suggest it can promote tumor cell growth and suppress the immune response. It is used in photography and is present in dyes, paints, varnishes oils, and motor fuels. In its oxidized form, it is more toxic and less degradable. It demonstrates high toxicity to aquatic organisms and rodents and may induce leukemia, renal tubular cell tumor, and liver cancer. It has also been found to influence immune cell responses and causes an increase in an allergic reaction by increasing interleukin-4 production and immunoglobulin E levels.
Enhancing Healthcare Team Outcomes
The interprofessional health care team, such as physicians, nurses, and pharmacists, play an essential role in monitoring patients on hydroquinone. It is important to monitor patients to ensure that they only use the medication as prescribed for no more than 5 to 6 months to limit side effects. Nursing staff can play a significant role in monitoring the patient and evaluating compliance, as it is important to follow instructions for the medication application, its frequency, keep a watchful eye for any adverse effect, which should be clearly explained to the patient. Patients should be instructed to cease using the medication if any irritation, hypersensitivity, or allergic reaction occurs. Pharmacists can review the use and adverse events when dispensing the drug, and monitor when the patient comes in for refills, alerting the prescribing clinician regarding any concerns. The rare, yet most potentially harmful, side effect of ochronosis needs to be explained to patients using hydroquinone, and they should be instructed to discontinue this medication immediately if this occurs. A collaborative interprofessional team approach to hydroquinone therapy will guide outcomes most effectively. [Level 5]
- Epstein JH. Postinflammatory hyperpigmentation. Clin Dermatol. 1989 Apr-Jun;7(2):55-65. [PubMed: 2667741]
- Stephens TJ, Babcock M, Bucay V, Gotz V. Split-face Evaluation of a Multi-ingredient Brightening Foam Versus a Reference Control in Women with Photodamaged Facial Skin. J Clin Aesthet Dermatol. 2018 Oct;11(10):24-28. [PMC free article: PMC6239159] [PubMed: 30519376]
- Tomita Y, Maeda K, Tagami H. Mechanisms for hyperpigmentation in postinflammatory pigmentation, urticaria pigmentosa and sunburn. Dermatologica. 1989;179 Suppl 1:49-53. [PubMed: 2550287]
- Katsambas AD, Stratigos AJ. Depigmenting and bleaching agents: coping with hyperpigmentation. Clin Dermatol. 2001 Jul-Aug;19(4):483-8. [PubMed: 11535393]
- Kauh YC, Zachian TF. Melasma. Adv Exp Med Biol. 1999;455:491-9. [PubMed: 10599387]
- Sofen B, Prado G, Emer J. Melasma and Post Inflammatory Hyperpigmentation: Management Update and Expert Opinion. Skin Therapy Lett. 2016 Jan;21(1):1-7. [PubMed: 27224897]
- Mahmoud BH, Ruvolo E, Hexsel CL, Liu Y, Owen MR, Kollias N, Lim HW, Hamzavi IH. Impact of long-wavelength UVA and visible light on melanocompetent skin. J Invest Dermatol. 2010 Aug;130(8):2092-7. [PubMed: 20410914]
- Lieberman R, Moy L. Estrogen receptor expression in melasma: results from facial skin of affected patients. J Drugs Dermatol. 2008 May;7(5):463-5. [PubMed: 18505139]
- Speeckaert R, Van Gele M, Speeckaert MM, Lambert J, van Geel N. The biology of hyperpigmentation syndromes. Pigment Cell Melanoma Res. 2014 Jul;27(4):512-24. [PubMed: 24612852]
- Bozzo P, Chua-Gocheco A, Einarson A. Safety of skin care products during pregnancy. Can Fam Physician. 2011 Jun;57(6):665-7. [PMC free article: PMC3114665] [PubMed: 21673209]
- Rendon MI, Barkovic S. Clinical Evaluation of a 4% Hydroquinone + 1% Retinol Treatment Regimen for Improving Melasma and Photodamage in Fitzpatrick Skin Types III-VI. J Drugs Dermatol. 2016 Nov 01;15(11):1435-1441. [PubMed: 28095558]
- Choukem SP, Efie DT, Djiogue S, Kaze FF, Mboue-Djieka Y, Boudjeko T, Dongo E, Gautier JF, Kengne AP. Effects of hydroquinone-containing creams on capillary glycemia before and after serial hand washings in Africans. PLoS One. 2018;13(8):e0202271. [PMC free article: PMC6112636] [PubMed: 30153255]
- Enguita FJ, Leitão AL. Hydroquinone: environmental pollution, toxicity, and microbial answers. Biomed Res Int. 2013;2013:542168. [PMC free article: PMC3727088] [PubMed: 23936816]
Fluocinolone; Hydroquinone; Tretinoin skin cream
What is this medicine?
FLUOCINOLONE; HYDROQUINONE; TRETINOIN (floo oh SIN oh lone; hye droe KWIN ohn; TRET i noe in) is a combination of a corticosteroid, a retinoid similar to vitamin A, and a drug used to lighten the skin. It is used on the skin to treat melasma. Melasma is a condition that causes dark spots on the face, especially the cheeks and forehead.
This medicine may be used for other purposes; ask your health care provider or pharmacist if you have questions.
COMMON BRAND NAME(S): Tri-Luma
What should I tell my health care provider before I take this medicine?
They need to know if you have any of these conditions:
- an unusual or allergic reaction to fluocinolone or any other corticosteroid, hydroquinone, tretinoin, vitamin A, sulfites, other medicines, foods, dyes, or preservatives
- pregnant or trying to get pregnant
How should I use this medicine?
This medicine is for external use only. Follow the directions on the prescription label. Gently wash your face with a mild cleanser. Do not use a washcloth to cleanse, just use your fingers. Rinse and pat your skin dry. Apply just enough cream to cover the discolored spots and about one-half inch of the normal skin surrounding the affected area. Lightly rub onto your skin. The medicine should become invisible almost at once. If you can still see the medicine, you are using too much. Use your medicine at regular intervals. Do not use it more often than directed.
Talk to your pediatrician regarding the use of this medicine in children. This medicine is not approved for use in children.
Overdosage: If you think you have taken too much of this medicine contact a poison control center or emergency room at once.
NOTE: This medicine is only for you. Do not share this medicine with others.
What if I miss a dose?
If you miss a dose, skip that dose and continue with your regular schedule. Do not use double or extra doses.
What may interact with this medicine?
- aminolevulinic acid
- benzoyl peroxide
- certain antibiotics
- phenothiazines like chlorpromazine, mesoridazine, prochlorperazine, thioridazine
- thiazide diuretics such as hydrochlorothiazide
This list may not describe all possible interactions. Give your health care provider a list of all the medicines, herbs, non-prescription drugs, or dietary supplements you use. Also tell them if you smoke, drink alcohol, or use illegal drugs. Some items may interact with your medicine.
What should I watch for while using this medicine?
Improvement of the treated areas occurs gradually. It may take up to 8 weeks of treatment before the full effects of this medicine are seen. After stopping treatment, the melasma spots may darken again over time and return.
Excessive or prolonged application of this cream may cause the treated areas or surrounding skin to become temporarily lighter than your normal skin. Discontinue application of this medicine to any such affected areas.
If sensitivity or increased irritation occurs or if the melasma spots become darker with treatment, stop using this medicine and contact your doctor.
Do not get this medicine in the eyes, inside the nose, on wounds, or any other sensitive areas of skin. If it gets in your eyes, rinse thoroughly with water and contact your doctor or health care professional.
This medicine can make you more sensitive to the sun. Keep out of the sun. If you cannot avoid being in the sun, wear protective clothing and use sunscreen. Do not use sun lamps or tanning beds/booths.
Do not use this medicine if you are pregnant or trying to become pregnant. Ask your doctor or health care professional for effective birth control measures if you are a female and able to have children.
To reduce skin dryness you may use a moisturizer in the morning after you wash your face.
Do not use the following products on the same areas that you are treating with this medicine, unless directed by your doctor or health care professional: other topical agents with a strong skin drying effect such as products with a high alcohol content, astringents, spices, the peel of lime or other citrus, medicated soaps or shampoos, permanent wave solutions, electrolysis, hair removers or waxes, or any other preparations or processes that might dry or irritate your skin. Ask your doctor or health care professional before using these products.
What side effects may I notice from receiving this medicine?
Side effects that you should report to your doctor or health care professional as soon as possible:
- allergic reactions like skin rash, itching or hives, swelling of the face, lips, or tongue
- crusting or swelling of the treated areas
- excessive or persistent burning, irritation, stinging or itching of the treated areas
- lightening of the skin surrounding the treated areas (halo hypopigmentation)
Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome):
- dry skin
- increased sensitivity to the sun
- mild itching or stinging of the treated areas
- mild peeling or mildly red, inflamed, and irritated skin
This list may not describe all possible side effects. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
Where should I keep my medicine?
Keep out of the reach of children.
Store at room temperature between 20 and 25 degrees C (68 and 77 degrees F). Do not freeze. Throw away any unused medicine after the expiration date.
NOTE: This sheet is a summary. It may not cover all possible information. If you have questions about this medicine, talk to your doctor, pharmacist, or health care provider.
Hydroquinone | Medicine
By Medicover Hospitals / 29 Nov 2020
Medicoverhospitals.in | Medicine | Hydroquinone
- Hydroquinone Uses
- Hydroquinone Side Effects
- Hydroquinone Precautions
- Hydroquinone Storage
- Frequently Asked Questions
What is Hydroquinone?
Hydroquinone is a Skin-lightening agent. It bleaches the skin which is helpful in treating a different form of hyperpigmentation. Hydroquinone bleaches the skin and decreases the number of melanocytes present. Melanocytes make melanin that produces the skin tone. Hydroquinone is available in the form of cream, gel, lotion and emulsion.
Hydroquinone is used to treat skin conditions which are related to Hyperpigmentation. It includes:
- Acne Scars
- Age Spots
- Post-inflammatory marks from psoriasis and eczema
Hydroquinone also helps to fade red or brown spots which have lingered but it won’t help inactive inflammation. The cream can help to minimize the acne scarring but it won’t have the effect on redness from active breakouts.
Hydroquinone Side Effects:
Some of the common side effects of Hydroquinone are:
- Mild burning or stinging of treated skin
- Mild itching, redness and other irritation
Some of the major side effects of Hydroquinone are:
- Skin redness, burning and stinging
- Skin dryness, cracks and bleeding
- Blisters or oozing
- Discoloration of the skin
- Inflammatory reaction
Before using Hydroquinone talk to your doctor if you’re allergic to any kind of skin related medications. The product can contain some inactive ingredients which can cause certain allergic reactions or any other serious problems.Before using Hydroquinone talk to your doctor if you’re having a medical history of:
How to use Hydroquinone?
Hydroquinone is applied each morning and at bedtime. Before using Hydroquinone follow the doctor’s advice carefully. It’s very important to do a patch test before going for the full applications. This will allow us in determining how the skin will react and whether it causes any adverse effects.Follow the trial application method:
- Rub a small amount of Hydroquinone in your forearm
- Cover the area with a bandage
- Wash the hands to prevent the product from staining the clothes and other materials
- Wait for 24 hours
- If you’re facing any severe adverse effects like itching and other irritation then avoid using it and consult with your doctor.
- If you’re not facing any of the side effects continue using it then you’re safe to use it.
- Take a small amount of the product and apply it across the entire area of the skin.
- Wash your hands before and after its use. It will prevent the product from affecting other areas of the skin. You should also use sunscreen while using Hydroquinone because sun exposure can make hyperpigmentation worse and can also show adverse effects of hydroquinone treatment.
- Cream: 2%- 4%
- Lotion: 2%
- Emulsion: 4%
- Solution: 2%- 4%
- Gel: 2%- 4%
Adults and children over 12 years should apply hydroquinone on the affected area and rub it gently for every 12 hours.
The skipped dose causes no problem. But with some medication, it won’t work if you don’t take the dosage on time. If you miss a dose some sudden chemical change may affect your body. In some cases, your doctor would advise you to take the prescribed medicine as soon as possible if you have missed the dose.
Overdose of a drug can be accidental. If you have taken more than the prescribed hydroquinone tablets there is a chance of getting a harmful effect on your body’s functions. Overdose of a medicine can lead to some medical emergency.
- Use as depilatory drug
Warnings for some health conditions:
Cetrorelix binds to the hormone receptor-releasing gonadotropin and functions as a potent inhibitor of gonadotropin secretion. It competes with natural GnRH for binding to pituitary cell membrane receptors and thus regulates the release of LH and FSH in a dose-dependent manner.
Hydroquinone vs. Retinol
|Hydroquinone is a Skin-lightening agent. It bleaches the skin which is helpful in treating a different form of hyperpigmentation. Hydroquinone bleaches the skin and decreases the number of melanocytes present.||Retinols are the best skincare products in the market. It is used to treat anti-ageing concerns as well as acne.|
|Hydroquinone is used to treat skin conditions which are related to Hyperpigmentation. It includes:
||Retinol is made from Vitamin A. It goes deep beneath the epidermis to your dermis. Retinol helps to neutralize free radicals for boosting the production of elastin and collagen. It treats:|
|Some of the common side effects of Hydroquinone are:
||Some of the common side effects of Retinol are:
|Some of the major side effects of Hydroquinone are:
||Some of the major side effects of Retinolare:
Hydroquinone Usage and Side Effects
Though very common, hyperpigmentation can be tough. Maybe your time in the sun left you speckled like a banana, or maybe you’re experiencing a change in hormones. Whatever the reason, we feel you. There are lots of treatment options out there, ranging from simple daily sunscreen use to in-office laser treatments — but today’s spotlight is on one special, topical ingredient: hydroquinone.
At Curology, we value transparency — so before we dive into the nitty-gritty, we’d like to address the context of hydroquinone. The controversy around this ingredient stems from the historical trend of skin-lightening or bleaching, which was driven by racist beauty ideals prizing light skin. Its misuse as a skin lightener or “bleach” stems from unjust, biased beauty ideals, which have historically been portrayed by the media.¹ Generally, dermatologists and medical experts agree that using hydroquinone to lighten overall skin tone is misuse, and they do not advise using it in this way.
All said, please know that hydroquinone is generally safe to use and is one of the most effective ingredients for treating hyperpigmentation, as long as it’s being used responsibly and as directed.
So, how does hydroquinone work?
Hydroquinone works for hyperpigmentation by acting as a tyrosinase inhibitor. I know that’s a mouthful — let us explain!
First, here are some important terms:
Melanin: Melanin is the natural pigment in our skin.
Melanocytes: Melanocytes are the cells in our skin that produce melanin.
Tyrosinase: Tyrosinase is a protein that’s needed to make melanin from melanocytes.
This basically means that hydroquinone stops your skin from making new pigment by blocking the melanocytes from making more melanin.²
How should hydroquinone be used?
Hydroquinone is a topical medication that is used to lighten hyperpigmented areas (like those pesky sunspots). It’s available with a prescription from your medical provider. A thin layer should be applied to dark spots and patches with the fingertips. Some dermatologists suggest using a Q-tip if there are only a few dark spots.
Another important tip: hydroquinone should only be used consistently for a few months followed by a break period of another few months.³ If you’re using a prescription-strength hydroquinone product, your medical provider will provide the specific “on-time” and “off-time.”
And don’t forget about sun protection! Dark spots can actually get worse from sun exposure, so it’s important to be consistent with sunscreen while using hydroquinone (and treating dark spots in general).
What are the possible side effects of hydroquinone?
Most people respond well to hydroquinone, so the best thing you can do for your skin is to follow your healthcare professional’s instructions — just keep an eye out for any irritation, itching, rashes, or allergic reactions.⁴
Ochronosis, another possible (but rare!) side effect, is a gradual blue/black or gray/blue darkening of the skin that is rarely seen after prolonged use of hydroquinone, especially at high concentrations.⁵ It’s also important to note that there are other potential unwanted effects besides these (learn more about them here).
When used responsibly, hydroquinone is one of the most effective ingredients when treating hyperpigmentation. There’s so much to learn, and we hope this blog was a useful resource for you!
• • •
Elisabeth Darj, et al. The fairer the better?. Use of potentially toxic skin bleaching products. African Health Sciences. 2015;15(4):1074–1080. doi:10.4314/ahs.v15i4.4
Vanessa Ngan. Hydroquinone. DermNet NZ. (2005, n.d.)
Chelsea Schwartz, et al. Hydroquinone. StatPearls [Internet]. (2020, Jan.)
Vanessa Ngan. Hydroquinone. DermNet NZ. (Ibid.)
Chelsea Schwartz, et al. Hydroquinone. StatPearls [Internet]. (Ibid.)
90,000 British Dermatologists: Whitening Creams Act as Household Solvents
Photo Credit, Getty Images
The British Local Government Association (LGA) has warned consumers of the dangers of using skin-whitening creams that act as a household solvent for removing paint.
This warning was issued after the Association’s trade compliance officers seized several batches of creams containing the whitening ingredient hydroquinone and possibly mercury.
According to the LGA, these toxic creams can be purchased in Britain by hand, from non-certified vendors, as well as online, at flea markets and flea markets.
Often, the exact composition of the ingredients is not indicated on the packaging of such products.
Why is hydroquinone dangerous?
Whitening creams are used to combat skin pigmentation, freckles, skin roughness, and they often include small doses of hydroquinone, but this component is toxic and affects the production of melanin, a pigment that protects the skin from harmful effects.
Due to serious side effects, creams containing hydroquinone, steroids or mercury are not commercially available in the UK and can only be purchased with a doctor’s prescription.
British experts warn that hydroquinone acts on the skin in the same way as paint thinner, removing its top layer, which can lead to an increased risk of skin cancer, as well as liver and kidney failure.
Mercury is no less dangerous and can cause the same health effects.
“Skin creams containing prohibited ingredients are very dangerous and can cause serious damage to your health, leave scarring and even be fatal, so they should never be used,” said Simon Blackburn of the LGA.
“Buyers should always check what is in the cream, be skeptical about the price being too low – as this is very likely a counterfeit and potentially dangerous product – and never use any product containing hydroquinone.If the product does not include the ingredients at all, then do not use it, “Blackburn advised British consumers.
“Ingredients in these beauty products can cause serious health problems, which is why the UK Skin Disease Foundation strongly discourages their use,” said Lisa Bickerstaff, a spokeswoman for the foundation.
Where were the illegal creams seized?
LGA has recently seized several batches of whitening creams smuggled into the country, including:
- 360 titles containing hydroquinone from a store in Dagenham, east London. The ingredients were incorrectly listed on the packages and did not meet EU standards. The shopkeeper was fined £ 6,500 ($ 7,300) and ordered to pay an additional £ 8,010 to the local council;
- in London’s Sazark neighborhood, local council officers withdrew 2,900 skin-whitening products from sale; most of them were imported from Nigeria in 2018 in a single consignment;
- An illegal shipment from Cameroon containing 250 kg of hydroquinone bleaching creams was seized at London Gatwick Airport;
- In 2018, a store owner was sentenced to 20 months in prison for the first time in Britain for selling illegal bleaching creams.The case was heard in the Royal Court of the Sazark District.
Chemistry and Physics. How to protect your skin and not fall prey to dyes | SOCIETY: Events | SOCIETY
We live in the south, and excessive skin pigmentation is a problem for us. We actively use lightening creams and serums. I would like to know how the constituent components of these funds work? Is their frequent use harmful?
Was smeared with mercury
The head of the beauty salon, cosmetologist Tatyana Rogova notes that until the twentieth century, mercury derivatives remained the main bleaching agent – a variety of mercury ointments, whitewash, and creams.But this led to severe intoxications and serious consequences for those who did not agree to put up with an uneven complexion. Mercury ointments have been replaced by such an ingredient as hydroquinone. Previously, it was used as a photoreactive, and later found application in medicine as an antipyretic and antiseptic. But it was quickly found that the agent was not safe, and hydroquinone was found to be highly toxic. After which it fell into disuse.
However, it remained in cosmetology as an ingredient with a pronounced whitening effect.
The mechanism of action of hydroquinone is based on the ability to block the synthesis of the amino acid tyrosine into a substance that is a precursor of melanin, a pigment that stains the skin a dark color. There are other substances with similar effects, but it is hydroquinone that is banned for use in the EU and Switzerland. What is the fault of hydroquinone?
The fact is that the effect on the skin of this substance is not limited to simply blocking the oxidation of tyrosine. Hydroquinone is capable of completely destroying melanocytes.Cells are dying with no hope of recovery. And since melanocytes are protective cells of the skin, their absence can lead to a very serious risk of cancer, primarily melanoma. Therefore, it is necessary to use products with hydroquinone over 2% under strict supervision and only as directed by a doctor.
The main thing is prevention
So what should be done? Do you really have to come to terms with such a defect as excessive pigmentation? Sparing methods are replacing hazardous substances! This is, firstly, the use of laser technologies, and secondly, nature itself has taken care of our beauty.There are plants containing active brightening components: sugar cane, pear leaf buds, bearberry, Swiss cressalat and many others. Plant extracts are extracted in the laboratory.
But most importantly, the use of preventive measures is much easier than solving the problems of skin pigmentation. Everyone should have a sunscreen cream in their arsenal.
Malvinas in the city
Nowadays young people dye their hair unimaginable colors. However, you can also meet older people with blue or crimson hair.
“As for the trend for bright colors, it came to us about three years ago. Peaked in popularity in 2018. As for the dyes themselves, there are many of them: from tinting to permanent. But it is important to understand that any bright shades are a pleasure that requires special attention and care. If the task is to get a pure color, be it pink, blue, lilac, red, etc. Then before that, the hair needs to be lightened, which means, subject them to a strength test! After all, human hair consists of 3% moisture and 97% protein (keratin), enriched with sulfur, trace elements and vitamins.When the hair is exposed to aggressive action of ammonia dyes, protein bonds are destroyed. And the hair becomes brittle and brittle, ”explains Tatiana Rogova.
As for direct dyes that do not contain lightening components, it is important to understand that they work on the surface of the hair, without penetrating deeply inside. Direct dyes are products that contain direct pigments that are already ready for hair coloring without the participation of chemical oxidation reactions, that is, they do not mix with oxidants.But the brightness of the staining in this case will be short-term. So, direct dyes are not able to paint over gray hair, but can only matte it by 50%.
It should also be taken into account that any pigment is not completely washed out. And if later there is a desire to change the color, then you will still have to “clean” the hair with the help of lightening compounds.
By the way
In the trend of 2020–2021 not just color. The essence of fashionable hair coloring is to combine shades, the number of which can be more than five.
Colorists offer courageous girls to dye their hair red using the most popular dyeing techniques. Soft transitions from darker red to lighter at the tips look very original. Keep in mind that just a bright canvas of one color is no longer relevant.
The fashionable shade “Hollywood opal” (combining platinum blond, pastel blue and pink) has also become an interesting way of dyeing hair in 2020–2021. But for dark hair, purple tint is suitable, while you can choose any shades – from dark purple to violet.
It is important to remember that today fashionable hair coloring is more inclined towards natural shades and their combination.
IMAGE-SKINCARE.RU »Light, radiant skin: the magic of hydroquinone
Sometimes an uneven complexion has nothing to do with the health of your skin – excessive pigment production is to blame. This can be extremely frustrating for those desperate to even out their skin tone, but there is something that can help: Hydroquinone, the active ingredient in our Iluma Intense Bleaching Serum .
In the past, most skin lightening products were ineffective (and some were even outright scams). This has caused many to distrust lightening drugs. But hydroquinone is the real lightening. You can get lighter, more radiant, smoother skin!
What is Hydroquinone?
Hydroquinone is one of several names used for the organic compound C6h5 (OH) 2. This compound, when absorbed by the skin, helps block the skin’s ability to produce melanin.Melanin is the culprit for darker areas of the skin such as freckles, age spots, or hyperpigmentation during pregnancy.
Hydroquinone does not cause dermatitis, unlike previously used skin brighteners, and it is also more effective.
How Do I Use Hydroquinone?
Of course, this depends on the concentration and type of preparation. Most whey formulations, including ours, are recommended for daily or two-time use.We suggest using Iluma Intense Bleaching Serum in the morning and in the evening.
How quickly can you see the results?
When you use a quality hydroquinone product such as IMAGE Skincare , you may notice uneven pigmentation almost immediately! Some people may notice results within a few hours. Others may see results after a few days or a week.
What side effects should I expect?
No side effects were identified. We add soothing ingredients such as tea tree oil to our formulations. However, it is always a good idea to test a product on a small area of skin first. Suddenly you are allergic.
If you want to get rid of sun spots, age spots or freckles – preparations with hydroquinone are the best choice!
How do you deal with age spots? What drugs do you use? Share your tips in the comments…
90,000 10 cosmetic ingredients banned in different countries
The European Union has banned or restricted the use of more than 1,300 chemicals, many of which will never appear in cosmetic products (such as jet fuel). In the United States, the ban applies to only 11 components. The EU requires additional information on the safety of ingredients before authorizing their use.That is, it is often more of a preventive measure, so not every prohibited component is 100% harmful and for everyone. However, the US prefers to ban ingredients only when there is sufficient scientific evidence.
Used in face lightening and whitening products. This substance is toxic and can contribute to the development of cancer. In order to prevent the EU banned its use, production and distribution in South Africa also fell under the ban, in Canada it is limited.Approved in the USA, Russia and China.
Herbal analogues of hydroquinone are extracts of mulberry and licorice, as well as alpha-arbutin obtained from bearberry – these components are no less effective for lightening age spots.
A toxic and pungent-smelling colorless gas used in cosmetics for disinfection and preservation. Simply put, it inhibits the formation of bacteria and fungi. Most common in nail varnish, hair dye and shampoo formulations.Studies show that this substance can cause mucosal irritation and dermatitis.
Formaldehyde has been banned for use in Japan and Sweden, while it is used in limited concentrations in the EU and Canada. In the USA, the use of formaldehyde is allowed in the composition of not more than 0.2%.
Alternative preservatives are phenoxyethanol, citric acid and sodium benzoate.
In cosmetics, phthalates are used to bind components or as a solvent.Most commonly found in nail and hair varnishes, perfumes and deodorants. Phthalates can lead to hormonal disorders, liver, kidney and lung dysfunctions, and they negatively affect the reproductive system. For example, 4% of newborns have developmental abnormalities – scientists associate this with abnormalities during pregnancy.
Both the FDA (Food and Drug Administration) in the US and the SCCP (European Scientific Commission for Consumer Products) in the EU agree that there is no clear information on what the use of these ingredients in cosmetics represents. danger to consumers.The FDA continues to monitor the situation while the SCCP has decided to restrict the use of certain phthalates.
Safe alternative to phthalates – copolymers, mixtures of natural oils and acetyl tributyl citrate (for example, used by the brand of varnishes Zoya).
Active ingredient in sunscreens. Can cause allergies, hormonal dysfunction – such results have been shown in experiments on rats and with test tubes. According to a number of tests, oxybenzone was found in the urine several hours after using the drug with its presence in the composition.In the US and EU countries, the concentration of oxybenzone in sunscreens is currently limited to 6% and in other cosmetic products to 0.5%.
Despite this, zinc oxide is safe and does just as well for sun protection.
A common preservative that is often referred to on labels as butylparaben, ethylparaben, methylparaben, propylparaben. Many organizations have raised concerns about parabens causing hormonal disruption, dermatitis and reproductive toxicity.Therefore, their use was banned in the countries of the European Union, Southeast Asia and the Philippines, but they are allowed in the United States.
It is also known that parabens are phytoestrogens that have a weak estrogenic effect on the body, but it is 10 thousand times weaker than the effect of natural phytoestrogens. However, not a single fact about harm has been confirmed by any research.
Coal tar dyes
Used in hair dyes, especially dark hair.It is an oil-derived carcinogen. Increasingly, there is information that the occurrence of cancer, lymphoma and myeloma is associated with long-term use of hair dyes. In seven out of ten regions studied (from the US, Norway, Sweden, Finland, Denmark, Japan), scientists found the highest prevalence of bladder cancer among stylists and clients exposed to hair dyes. The so-called coal tar is often found in anti-dandruff shampoo formulations. The substance is banned in Canada and European countries.
A study by the Campaign for Safe Cosmetics found over 60% of lipstick samples contain lead. This carcinogen is widely recognized in the industry but is almost never mentioned on the label. Lead intoxication can lead to disruption of the nervous system, gastrointestinal tract and liver. Currently, this component is banned in Canada and European countries, and in the United States, only eye creams have been banned.
Antibacterial ingredient added to shampoos, creams and lotions. Bithionol causes an increased sensitivity of the skin to the sun, the manifestation of itching and redness. The ban on its inclusion in products affected cosmetics from Canada, Europe and the United States.
Experts still doubt the effectiveness of this substance for enamel strengthening. Research has been carried out by the National Toxicology Program, with the assistance of the US State Health Service, which has confirmed that fluoride, although one of the natural components of dental tissue, should not enter the body as fluoride.Excessive amounts of fluoride cause fluorosis – stains on the enamel caused by demineralization.
In many countries, there is a program for centralized fluoridation of tap water as a prevention or reduction of caries. Artificial fluoridated water is supplied to residents of about 24 countries, including Australia, Brazil, Chile, Ireland, Malaysia, the United States and Vietnam. Fluoridation of water is rare in continental Europe, and Canada, Israel, China, Denmark, Japan and several other countries have completely abandoned it.
Carmine is obtained from the chitinous cover of cochineal insects, which are red in color. It is often used for the production of decorative cosmetics. Haram banned cosmetics with carmine, since in the Islamic religion insects are also considered animals.
The European Union, Israel and India have banned the sale of any cosmetic or cosmetic ingredient that has been tested on animals. And in countries professing Islam, cosmetics based on harmful chemicals, animal fats, alcohol (alcohol-based cosmetics), gelatin, animal protein and glycerin are prohibited.
Information on a wide variety of ingredients can be found on the EWG ‘Skin Deep’ cosmetic database.
90,000 Carcinogenic hydroquinone and mercury ointments. Why many skin whitening products are unsafe
And why skin whitening has become so popular in Africa – read in the long read of the historian Alexei Tselunov.
The data provided by the author is not fully evidence of the harm or benefits of certain drugs, but is a review of medical hypotheses, results of clinical trials and individual cases.
Numerous methods of skin lightening are known. Some of them relate to medical procedures for the treatment of pigmentation disorders, others are used only in cosmetology, and still others are artisanal “grandmother’s” recipes or fantasies of beauty bloggers. The first and second can be classified according to the type of exposure. The physical ones include laser correction and cryotherapy, and the chemical ones are the treatment with various reagents or their mixtures, which act directly on the molecular mechanisms of pigmentation formation (hydroquinone, tretinoin, glutathione, etc.).) or whiten only the skin surface due to the oxidation of pigments (hydrogen peroxide, sodium hypochlorite) or leaching (various acids). Here we will focus on chemical approaches, because, unlike physical manipulations, many of the substances used not only act during the procedure, but are also able to penetrate the skin deep into the body, enter the circulatory system and enter the internal organs, causing long-term consequences.
People who practice skin whitening note positive results: increased attractiveness, confidence and self-esteem, getting rid of bodily defects. However, long-term skin whitening and the use of toxic and potent agents have been associated with a variety of serious consequences, ranging from dyschromia to more alarming systemic side effects, including diabetes and hypertension. As a result, the practice of skin whitening is a public health concern, and the import and sale of skin whitening products is prohibited or strictly regulated in many African, Asian, European and North American countries.
Chemical analysis of skin whitening products raises doubts about their safety, as they contain hazardous ingredients such as mercury and hydroquinone in excess of the established standards. Researchers have linked these toxic substances to adverse health effects.
Prevalence of skin whitening
Global bleaching prevalence analyzed in a 2018 meta-analysis based on 68 studies with 67,665 participants.The calculated average lifetime prevalence of skin discoloration was 27.7%. Small fluctuations were observed across the regions: In Africa – 27.1%, in Asia – 23.1%, in the Middle East – 23.7%. In Asia, since the late 1980s, the consumption of whitening cosmetics has remained at a consistently high level, and white complexion is considered fashionable in Japan, being a symbolic physical characteristic of the Japanese. In Hong Kong, 27% use skin whitening creams. In South Korea, China, Malaysia and the Philippines, about 40% of women use bleaching.
In India, the share of skin lightening products reaches 61% of all cosmetics sold.
There is a wide selection of different skin lightening creams in the Saudi Arabian markets, which are either imported from overseas or handcrafted locally. A 2009 review reported on the practice of skin whitening among Africans and Afro-Caribbean people living in European countries, including the UK and France.In fact, the over-the-counter use of hydroquinone is currently prohibited in Europe, although this drug and other depigmenting agents are still available illegally in the EU markets. In a study in Paris and the surrounding area, it was estimated that between 16% and 28% of adult African women seeking dermatological care regularly use skin whitening products, with 31% starting to practice whitening while in France.
According to a meta-analysis, the highest prevalence rates are associated with men (28.0%), use of topical corticosteroids (51.8%), young people under 30 (55.9%), persons with only primary education (31.6% ), residents of cities or towns (74.9%)
Topical corticosteroids were the most popular drug with 51.8%, followed by mercury and its derivatives with 34.4%.Hydroquinone – 47.5%, glycolic, kojic or fruit acids, vitamins A and C and other drugs of unknown composition – 32.7%. Most often, skin whitening was used by young people 30 years old and younger – 55.9%, then people 31–49 years old – 25.9% and over 50 years old – 6.1%.
Thus, skin whitening is a global phenomenon. This trend is reflected in the aggressive marketing, advertising, distribution and sale of specialty cosmetics. The production and sale of skin whitening products has become a multi-billion dollar global industry.According to the latest projections, global spending on skin lightening products will reach $ 12.3 billion by 2027.
Skin lightening and whitening products
First, we look at drugs used in medicine to treat skin hyperpigmentation, which are also used for whitening.
Hydroquinone is one of the most commonly used drugs for the treatment of skin hyperpigmentation. In the United States, hydroquinone is available as over-the-counter whitening creams at 2% and as prescription drugs at 1.5–4%.It is a small hydrophilic molecule that effectively penetrates human skin, and up to 43% of the introduced substance reaches the circulatory system. Hydroquinone works by inhibiting the enzymatic oxidation of tyrosine to 3,4-dihydroxyphenylalanine (DOPA). Hydroquinone acts as an effective inhibitor of melanogenesis in vitro and in vivo, suppressing the synthesis of DNA and RNA, as well as reducing the activity of tyrosinase mainly in melanocytes, that is, it exhibits cytotoxicity. The drug is a strong reducing agent that is rapidly converted to hydroquinone and n -benzoquinone, both of which are toxic to melanocytes.
The first clinical study to demonstrate the effectiveness of hydroquinone in skin lightening was published in 1961, and subsequent work only confirmed this conclusion. Hydroquinone can also be used in combination with other compounds to tune its action. The combined use of hydroquinone with azelaic acid enhances skin absorption and increases dermal delivery of both compounds. The joint preparation of hydroquinone and salicylic acid is better retained in the skin.The use of hydroquinone with tranexamic acid increases the deposition of both drugs on the skin, resulting in improved targeting by reducing transdermal penetration. Compounds structurally related to hydroquinone include arbutin (β-D-glucopyranoside hydroquinone) and mequinol (hydroquinone monomethyl ester), which inhibit tyrosinase by mechanisms similar to hydroquinone. These products are also commonly found in over-the-counter skin lightening products in the US and other countries.
Simple and allergic contact dermatitis followed by post-inflammatory dyspigmentation are potential side effects that occur when hydroquinone is used during skin whitening. Pigmentation of the nail plate and peripheral neuropathy have also been reported as complications following hydroquinone. There is a known case of the development of chronic symmetric sensorimotor polyneuropathy and autonomic neuropathy, the relief of which came only 4 months after the termination of the use of skin whitening agents based on hydroquinone.Exogenous ochronosis with progressive asymptomatic hyperpigmentation and papules on sun-exposed skin is another side effect of hydroquinone. The histology of the affected skin shows degeneration of collagen and elastic fibers and deposition of ocher fibers in the dermis. The scientific literature describes at least 789 cases of exogenous ochronosis, 756 of which occurred in Africa. However, caution should be exercised in the interpretation of these data due to the presence of additional factors that may explain the higher rates of exogenous ochronosis in Africa: use of antimalarial drugs, lack of biopsy data from lesions, insufficient use of sunscreen during skin bleaching, high concentrations of hydroquinone drugs and products containing resorcinol and other agents.In the United States, where hydroquinone preparations have been popular for a long time, the reported incidence of exogenous ochronosis is relatively low. Another important theoretical side effect of skin whitening with hydroquinone preparations is the development of malignant neoplasms of the skin and internal organs. Hydroquinone is a metabolite of benzene, a leucogenic agent, and is also associated with the development of mononuclear cell leukemia in rats exposed to oral hydroquinone for two years.
Since the practice of skin whitening involves the application of high concentrations of hydroquinone to large areas of the body, it can be argued that this poses an increased risk of developing malignant neoplasms.There are at least two known confirmations of the appearance of malignant tumors due to skin whitening with hydroquinone agents. It is suggested that the reason lies in the pro-carcinogenic effect of hydroquinone or in the suppression of the natural photoprotective effect of melanin.
In the European Union, hydroquinone is classified as a carcinogen and mutagen.
Azelaic (Nonanedioic) Acid is a saturated dicarboxylic acid with skin brightening properties.Interestingly, dicarboxylic acids are produced in cultures of the yeast Pityrosporum and are believed to be responsible for the hypopigmentation seen in tinea versicolor. Although dicarboxylic acids, including azelaic acid, inhibit tyrosinase, their affinity is low and cytotoxic doses are required to induce inhibition in vivo. Neither in vivo nor in vitro melanocidal or depigmenting effects are known for them. Azelaic acid also has anti-inflammatory activity and is FDA approved with indications for the treatment of acne vulgaris and rosacea.The anti-inflammatory properties of azelaic acid may also play a role in its effectiveness in post-inflammatory hyperpigmentation and melasma. The use of azelaic acid for the treatment of melasma was found to be more effective than 2% hydroquinone and equivalent to the prescription 4% hydroquinone. Local side effects include burning, itching, scaling, and erythema. No exogenous ochronosis was observed. Several patients have developed comedones caused by subsequent sunscreen application.
α-Viniferine is an active oligostilbene component of the Caragana sinica plant. Local application of natural α-viniferin reduces the production of melanin in vivo and in vitro without disrupting the viability and proliferation of melanocytes. Treatment of mouse melanoma and melanocyte cell lines with α-viniferin suppressed melanin production without affecting their viability. A small clinical study in 23 patients with melasma and facial ephelids demonstrated that topical application of C cream.sinica for 8 consecutive weeks resulted in a significant decrease in the melanin index and an increase in lightening compared to the control group. All patients completed the study without complaints of itching or other side effects.
Diacetyl caffeic acid cyclohexyl ester (DACE) is a caffeic acid derivative that inhibits melanin production in αMSH-activated murine melanoma cells. The drug prevents skin hyperpigmentation after UV irradiation, and also lowers the level of tyrosinase in vivo.In addition, DACE inhibited in vitro melanin secretion in α-MSH-stimulated human epidermal melanocytes and melanoma cell lines. However, further research is needed to assess the safety of the drug.
Tranexamic acid is an FDA-approved antifibrinolytic drug for the treatment of menorrhagia and dental procedures in patients with hemophilia to prevent bleeding and blood loss. In 1979, it was noted that melasma improved in patients taking tranexamic acid.Subsequent studies, including recent retrospective and randomized controlled trials, have confirmed these findings. Tranexamic acid can be applied topically and given by intradermal injection, but most studies have used oral delivery. Doses for the treatment of melasma are significantly lower than for hematological indications.
Adverse side effects develop in 7.1% of patients. Most are transient, but deep vein thrombosis is rare, requiring immediate discontinuation of the drug.
Before starting therapy, it is necessary to conduct a thorough screening to exclude persons with thromboembolism, taking oral contraceptives, having a stroke or having heart disease. Tranexamic acid is thought to act by blocking the conversion of plasminogen to plasmin in keratinocytes; this can lead to a decrease in the amount of free arachidonic acid and a subsequent decrease in the production of prostaglandins, thereby reducing melanogenesis.
Kojic acid is a complexing agent first discovered in Aspergillus molds.It acts by chelating copper at the tyrosinase active site, blocking the conversion of tyrosine to melanin. Kojic acid has been shown to be effective in treating melasma. Side effects include redness, burning, and peeling, and subside by the third week after drug withdrawal.
Tretinoin , the acid form of vitamin A, and other retinoids have a depigmenting effect by increasing the turnover of keratinocytes and reducing the transfer of melanosomes to keratinocytes. Retinoids are used alone or in combination with other drugs to treat melasma, post-inflammatory hyperpigmentation, and other pigmentation disorders.In addition, tretinoin is FDA approved and indicated for use in skin photoaging. Its anti-aging action includes the normalization of pigmentation in chronically photo-damaged skin. The only side effects are occasional flaking, dryness, and erythema; they are removed by reducing the frequency of tretinoin use or by refusing to apply the drug to the reaction area for several days.
Glutathione is a tripeptide consisting of cysteine, glycine and glutamate residues, which exists in two forms: reduced intracellular (GSH) and oxidized (GSSG).The brightening effect of glutathione is thought to be due to its antioxidant properties; the ability to switch the production of eumelanin to pheomelanin, a type of melanin found in people with fair skin; inhibitory action against tyrosinase due to binding to the copper-containing active site of this enzyme; and by interfering with the transfer of tyrosinase into premelanosomes. There are limited data to support the effectiveness of glutathione. One study in Thailand showed skin lightening in 30 people who took 250 mg of glutathione orally twice a day.
The use of parenteral glutathione for skin whitening is spreading in the UK. This service is provided by beauty clinics; in some salons, glutathione is administered to individuals without medical training. There is no authoritative information on the effectiveness and safety of this practice.
FDA warns of the dangers of using injectable skin lightening products, including glutathione. A similar warning was issued by the Philippine Dermatological Society .
Adverse effects reported with intravenous glutathione for skin whitening include neuro-, renal and hepatic toxicity, transient headaches and adverse skin rashes – Stevens-Johnson syndrome and toxic epidermal necrolysis. Other potential risks are due to injection – transmission of infectious agents, including HIV, hepatitis C and B. This is especially dangerous when this method is used by unskilled people.Given that glutathione plays an important role in the transition from eumelanin to pheomelanin synthesis, there are concerns about the long-term risk of skin cancer.
Topical steroids are anti-inflammatory drugs used to treat many inflammatory skin conditions. They are popular depigmenting agents used for skin whitening, and the widespread use of illegal clobetasol-containing products is believed by doctors to be responsible for most of the severe side effects caused by skin whitening in French-speaking countries.The depigmenting effect of steroids occurs through an initial local vasoconstriction that occurs when applied to the skin, which gives the impression of an immediate reduction in skin pigmentation. As a result, topical steroids discolor by inhibiting epidermal melanogenesis.
The use of steroids for more than three weeks, especially on the thin skin of the face and on the folds, is associated with a number of side effects: the development of stretch marks, perianal dermatitis, rosacea-like rashes, acne, telangiectasias, poor wound healing, mild bruising and hypertrichosis.Other side effects: ophthalmic problems (cataracts, glaucoma, eye infections and blindness) associated with the use of topical steroids on the face, especially on the eyelids, and aseptic osteonecrosis. Skin infections, dermatophytosis, erysipeloid, scabies, and warts can occur as a complication of the misuse of topical steroids. An atypical manifestation or masking of the clinical picture of these skin diseases is often observed. The use of powerful topical steroids leads to systemic side effects, including diabetes and hypertension, Cushing’s syndrome, immunosuppression, and adrenal insufficiency.
Mercury salts (iodine mercury, 1-3% in skin whitening products; mercury (II) amidochloride, Hg (NH 2 ) Cl, 1-10%) depigment skin through inhibition of melanin formation. This is because mercury salts compete with copper for tyrosinase. Historically, chronic mercury poisoning has occurred in the context of industrial exposure, such as in the manufacture of felt hats, or during the use of mercury drugs to treat syphilis and impetigo.
Currently, skin lightening also leads to mercury poisoning.
The peculiarities of these poisonings, also known as “hatter disease” and immortalized by Lewis Carroll in “Alice in Wonderland”, are psychiatric (memory impairment, intellectual impairment, inattention and depression) and neurological (irritability, memory loss and neuropathy ) problems.
In case of mercury poisoning, renal function is impaired (minimal changes or membranous glomerulonephritis) and a paradoxical increase in skin pigmentation occurs.The latter is either due to an unexplained increase in the production of melanin, or due to the direct deposition of microscopic droplets of metallic mercury in the dermis. Mercury salts are absorbed exclusively through the skin, and, therefore, during biopsy of lesions, perifollicular deposition of mercury is observed during mercury-induced hyperpigmentation. The use of mercury agents for skin lightening by pregnant or lactating women has been associated with adverse neonatal effects, including anemia, renal failure, and cataracts.
Glycolic acids are α-hydroxy acids derived from sugar cane. In low concentrations, they have a loosening effect on the epidermis, and in high concentrations, they provoke epidermolysis. Both of these actions lead to the removal of the surface layers of the epidermis and, therefore, to a depigmenting effect. Other mechanisms of depigmentation include accelerating the turnover of keratinocytes with a decrease in their loading time into melanosomes. Side effects with this remedy: contact dermatitis with risk of post-inflammatory hyperpigmentation.
Oxidants are found in various commercial bleaching products. Powerful skin irritants are sodium hypochlorite (NaOCl, the active ingredient in household bleach Whiteness), hypochlorous acid (HOCl) and hydrogen peroxide (h3O2). Hypochlorite is also accompanied by its hydrolysis product, sodium hydroxide (NaOH). The use of such formulations can provoke discrete sensory symptoms, especially a burning sensation. The reactivity of NaOCl liquid whitener with the stratum corneum has been proven even at a concentration of 1%.A pure hypochlorite solution corresponding to a concentration of 4% NaOCl severely damages the stratum corneum.
Sodium hypochlorite can cause allergic reactions. Hypersensitivity to household bleach has been reported. Symptoms included a skin rash that spread from the fingertips to the joints of the hands on both hands and edema accompanied by red-black erosions.
Baths with NaOCl are used to treat moderate to severe atopic dermatitis or eczema.Solutions with a concentration of 0.05–0.06% of an oxidizing agent are considered safe. Severe chemical burns occur when more NaOCl is used, but lower concentrations are ineffective.
Hydrogen peroxide is an unstable oxidizing agent, therefore it is rarely used in skin whitening products. Concentrated, caustic peroxide can cause local tissue damage. Hydrogen peroxide is also capable of exerting direct cytotoxic effects through lipid peroxidation.When exposed to the skin, inflammation, blisters and more serious damage occur. Eye contact with a 3% solution causes immediate burning, irritation, watery eyes and blurred vision, but serious damage is unlikely. Contact with more concentrated solutions of hydrogen peroxide (> 10%) threatens corneal ulceration or perforation.
Peeling is also sometimes used for skin whitening. Peeling is classified by depth of penetration: superficial, medium and deep.The first reaches the epidermis, the second reaches the papillary dermis, and the third reaches the reticular dermis.
The depth depends on the type and concentration of the substance used, the pH of the solution and the exposure time. Deep peels should be used very carefully, given the high risk of side effects such as pigmentation and scarring. For surface peels, glycolic acid, salicylic acid, Jessner’s solution (lactic, salicylic acid and resorcinol in a 1: 1: 1 ratio of 7 or 14%) and trichloroacetic acid in a concentration of 10-30% are used; for the average – 35-50% and 88% phenol.For deep peeling, use the Baker-Gordon formula – a combination of 88% phenol, water, liquid soap and croton oil. Peeling compositions also often include lactic acid, salicylic acid, tretinoin, Jessner’s solution, thioglycolic acid, resorcinol, pyruvic acid, and a combination of salicylic and mandelic acids.
Post-peel complications more often occur in patients with a higher skin phototype on the Fitzpatrick scale and during medium and deep peels. Post-inflammatory pigmentation, erythema, and edema are more common in patients with ethnically dark skin.This can be avoided with the correct choice of formulation and depth and the use of suitable photoprotection. Allergic reactions, hypertrophic scarring, keloid formation, and delayed healing occur. Other possible complications are acneform eruptions, milia, lines, and persistent erythema.
The harmful effects of skin-whitening cosmetics are exacerbated by the rise in temperature as a result of climate change. The main function of melanin is to protect the skin from sun damage and photodamage by absorbing ultraviolet radiation.
Thus, in the face of global warming, which increases the already excessively high UV index in Africa, Central America and Southeast Asia, the destruction of melanin as a result of skin bleaching increases the likelihood that sun exposure will lead to premature aging, as well as to various types of skin cancer.
There are many known side effects of skin whitening:
- Long-term exposure to mercury derivatives causes serious renal, pulmonary and neurological damage as well as psychological disorders including anxiety, depression and psychosis.
- Hydroquinone provokes contact dermatitis and ochronosis; potential carcinogen.
- Corticosteroids can lead to diabetes and dermatological complications such as mycoses, striae, telangiectasias and hypertrichosis.
- Stillbirth, low birth weight, and neonatal infections are possible in pregnant women using bleaching agents.
The development of pigmentation-controlling pharmacological agents for the prevention and treatment of skin lesions is an important goal in medicine and cosmetology.However, not all drugs are equally useful for their cosmetic use, and some of them are extremely poisonous and prohibited.
90,000 Doctors warned against using cosmetics with carcinogens
In June 2021, scientists from the University of Notre Dame and their colleagues at Indiana and Toronto Universities, as well as the Swiss Higher Technical School of Zurich, found 90,010 high levels of per- and polyfluoroalkyl substances (PFAS) in half of the cosmetics they studied, many of which cause cancer.The study included foundations, waterproof mascaras and liquid lipsticks purchased in the USA and Canada.
In 2017, toxic substances were found in French hygienic lipsticks and lip balms. In a study commissioned by the Que Choisir consumer advocacy group, scientists found in half of the samples studied mineral oils with saturated hydrocarbons, which, if ingested, can cause inflammation in the lymph nodes and liver.
However, in cosmetics, both decorative and care, you can find components that have been used for a long time – and are very harmful.
For example, formaldehyde, which can be found in shampoos, hairsprays and other styling products, and in creams.
“On labels it can be designated as formalin, formic. In fact, it is used as a preservative for creams, and if you see that the shelf life of the cream is five years, then it is better to refuse to buy it, since a dangerous preservative is clearly added there, ”says Tatyana Sulima, a dermatologist, trichologist at the NAKFF Oncology Clinic.
According to the doctor, when buying cosmetics, you should pay attention to the content of hydroquinone.“It is most commonly found in anti-pigmentation formulations, but it is also found in concealers, cleansers, or sunscreens. Such drugs reduce the production of melatonin, which increases the effect of ultraviolet radiation on the deeper layers of the skin, ”explains Tatiana Sulima.
Hydroquinone lowers the protective barrier of the skin, which is why melatonin-producing cells can mutate – this threatens the development of skin cancer.
At the same time, in order to prevent oncological diseases of the skin, it is necessary to use sunscreens, recalls Ali Mudunov, professor, head of the department of head and neck tumors at the Lapino-2 Cancer Center.“The main provocateur of skin cancer is ultraviolet light. Therefore, it is especially important to use sunscreen, avoid aggressive solar radiation and give up tanning beds, even in small doses, ”warns the doctor.
According to Ali Mudunov, quality control over cosmetic products has been strengthened recently.“On the market, especially in well-known brands, there are practically no dangerous carcinogens in cosmetics,” he believes. However, Tatiana Sulima is sure that some components are still quite common.
In particular, it is propylene glycol. “The labels usually write its full name, or just“ propylene ”. It is a transparent liquid that is chemically obtained from oil refined products, says Tatiana Sulima. – The component is used, as a rule, to moisturize the skin, but it is included in different types of products: decorative and care cosmetics, hair products, and most dangerous – it is often found in children’s shampoos and oils.
According to her, parabens used in cosmetics as preservatives are also relatively dangerous. And also aluminum acetate, which is added as a protective agent for the skin.
As Ali Mudunov explains, skin cancer can develop if you use cosmetics with hazardous substances “not one day, but constantly for several years.”
At the same time, the doctor warns against dangerous cosmetic procedures. Namely – from manicure using ultraviolet lamps.
“There are studies that support the connection between UV manicure and acral lentiginous – it develops on the palms, soles and nails – and subungual melanoma,” he notes. “This type of cancer is not so common, in about 10% of cases, but in recent decades, when extended nails and manicure with gel polish became popular, the number of cases has increased.”
Ali Mudunov adds that the fashion for naturalness can only delight doctors. “Natural looking skin, nails and hair is the best way to reduce the risk of skin cancers,” the professor concludes.
Hydroquinone (para-dihydroxybenzene, benzene-1,4-diol, quinol) is an aromatic organic compound, a representative of diatomic phenols with the chemical formula C 6 H 4 (OH) 2 , isomer of pyrocatechol and resorcinol. The name “ hydroquinone ” was given to the compound by F. Wöhler because of the similarity of properties with the quinone, from which Wöhler synthesized it. A strong reducing agent, used as a developer in photography, an antioxidant in the chemical industry, a reagent for the determination of niobium, tungsten, gold and cesium in analytical chemistry.
Trade name: H-142 .
J. B. Cavantou (left) and P. J. Pelletier (right), who first received hydroquinone
was first isolated by French chemists Pierre Joseph Pelletier and Joseph Bienneme Cavantu in the distillation of quinic acid in 1820. The synthesis of hydroquinone was first carried out by Friedrich Wöhler in 1844 by the reduction of quinone.Wöhler also gave it its modern name and described its properties.
William Abney in 1880 discovered the exhibiting properties of the compound, which led to the development of industrial synthesis methods. Further experiments with hydroquinone led to the creation of developers with two developing agents. The first of these developers was obtained by Henry J. Newton in 1889, adding hydroquinone to an eikonogenic developer, and obtaining a final composition that used the best properties of both developing substances.Soon after, metol-hydroquinone developers (denoted by the symbols MQ in English-speaking sources) were proposed, in which the phenomenon superadditivity was noticed – an effect when a developer with two different developing substances works significantly more actively than it should be if proceed from the calculation of the sum of the activity of both developing substances. The superadditivity effect was confirmed and substantiated by the scientific work of Levenson in the late 1940s, which showed that in this case, the development of the image is carried out by metol, and the role of hydroquinone is to regenerate the spent metol.
The discovery by J.D. Kendall of the developing ability of phenidone in 1940 led to the creation of an even more efficient system of phenidone-hydroquinone developers ( PQ in the English-language literature). Phenidone is not very suitable for use as the only developing substance, since it gives a strong veiling of the photographic material, but in superadditive developers with hydroquinone this feature disappears, giving a high-quality final image, a significant acceleration of the processing process, less toxicity and other advantages compared to metol-hydroquinone formulations …
White or colorless prismatic crystals, sweetish in taste. It has modifications that differ in physical properties: the stable α-modification has a melting point of 173.8-174.8 ° C and a density of 1.36 g / cm 2 , an unstable γ-modification – a melting point of 169 ° C and a density of 1.325 g / cm 2 . It has a molar mass of 110.11 g / mol, a boiling point of 286.5 ° C, and a flash point of 165 ° C. Sublimes at 163.5 ° C (10 mm Hg.Art.).
Soluble in water (5.26 g / 100 ml at 5 ° C, 21.21 g / 100 ml at 50 ° C, 56.25 g / 100 ml at 70 ° C), alcohol (127.27 g / 100 g), acetone (77.94 g / 100 g). Forms clathrates. In particular, the methanol clathrate has the formula 3C 6 H 6 O 2 CH 3 OH.
The reagent may contain impurities that look like an insoluble black powder. The amount of impurities increases with prolonged or improper storage, and with a large amount of them, the reagent becomes unusable.
Strong reducing agent. The process of interaction with oxidants occurs in two stages – at the first, hydroquinone is converted into quinhydrone, at the second – into 4-benzoquinone.
When interacting with an aqueous solution of potassium carbonate at 130 ° C it turns into 2,5-dihydroxybenzoic acid, with methylamine under pressure at 200 ° C it forms 4-methylaminophenol, with maleic anhydride – naphthazarin, with phthalic anhydride it gives quinizarin. Forms simple mono – and diesters when treated with alkylating reagents.
Hydroquinone can be determined using color reactions:
- appearance of a color from yellow-green to golden when hydroquinone is heated to 100 ° C with sodium nitrite and dilute sulfuric acid. When sodium hydroxide is added, the color changes to yellow-brown;
- Appearance of a dark red color with the addition of nitric acid, gradually turning into yellow.
Has developing properties, reducing silver bromide in alkaline solutions with the formation of 4-benzoquinone and hydrogen bromide with the general equation:
- + 2AgBr → OH – + 2Ag + 9055 2HBr
- in an alkaline medium hydroquinone dissociates into the hydroquinone dianion:
- ⇌ H + OH – + 2H +
- ⇌ −e – ⇌ − e –
- silver ions are reduced to metallic silver:
- 2Ag + + 2e – ⟶ 2Ag
starts at pH above 9 ,.The process consists of several stages:
- hydroquinone is oxidized at the center with the formation at the first stage of the ion of semiquinone and 4-benzoquinone at the second:
Hydroquinone was originally obtained from quinone.Various variants of this method are still used for laboratory preparation of the reagent; for this, for example, a reduction of an aqueous solution of 4-benzoquinone is carried out using sulfur dioxide.
In industry, synthesized by the following methods:
- by oxidation of 1,4-diisopropylbenzene with air, then acid hydrolysis of the resulting bis-hydroperoxide is carried out to form hydroquinone and acetone;
- by hydroxylation of phenol with 70% hydrogen peroxide at 90 ° C using 75% phosphoric acid or 65% perchloric acid as catalysts.As a result of the reaction, a mixture of hydroquinone and pyrocatechol is formed, which is further separated by rectification;
- the interaction of phenol and acetone with the formation of 4-isopropylphenol, which is oxidized with hydrogen peroxide in an acidic medium with the formation of hydroquinone and acetone;
- by oxidation of aniline sulfate with manganese dioxide or chromic acid to 4-benzoquinone, then 4-benzoquinone is reduced with powdered iron in water at 70-80 ° C in the presence of sodium hydrosulfite with a total reaction yield of 74-84%.
Technical conditions for the production of hydroquinone in the USSR and the Russian Federation are established by GOST 19627-74. In accordance with it, two grades of the reagent are produced – the highest and the first. The highest grade looks like a white or grayish-white powder and contains 99.5% of the main substance, the first one – as white with a yellowish tinge and contains 99% of the main substance.
Although a fairly pure reagent is usually obtained in industrial production, if necessary, a greater degree of purification can be obtained by recrystallizing the commercial reagent from thoroughly deoxygenated water.
The estimate of the US production capacity for the production of hydroquinone was about 11.3 thousand tons per year (as of 1965).
It is used:
- in analytical chemistry for the determination of pH and some metal ions;
- in photography as a developing agent;
- in the production of organic dyes, medicines, photographic materials as raw materials;
- in the production of food and rubbers as an antioxidant;
- in cosmetics used in tanning products and as hair dye;
- in cosmetic medicine for skin whitening.Because of its carcinogenicity, its use is limited .;
- as an inhibitor of the polymerization reaction of vinyl monomers, including methyl methacrylate used in chemical-curing dental composite materials.
Application in analytical chemistry
- photometric determination of niobium and tungsten;
- titrimetric determination of gold and cesium ions;
- for pH determination using the quinhydrone electrode method, for which quinhydrone is prepared in the form of an equimolar mixture of quinone and hydroquinone.
Application in photography
As the only developing agent, it is usually used only in special developers intended for obtaining high optical density, for example for reproduction or printing purposes, or for obtaining a brown color on silver bromide papers.
Formulations with hydroquinone are sensitive to temperature changes: 18 ° C is optimal, at 19 ° C the operating speed is normal, but veiling begins already at 20 ° C; when the temperature drops to 10 ° C, the development practically stops and when it reaches 5 ° C it stops completely.
Usually used in developers together with metol or fenidone, while the veiling power inherent in hydroquinone disappears.
As of 2006, it is known that drugs containing more than 5% hydroquinone have been banned in Nigeria due to their misuse, as well as the existence in Germany of restrictions on the use of drugs with hydroquinone, where they can only be used for cases of pathological pigmentation and cannot be used for children and adolescents under 12 years of age.
Has a weak disinfecting effect, similar to that of phenol.
Toxic. The LD50 is 302 mg / kg (rats, oral). When ingested, it is oxidized to 4-benzoquinone, which converts hemoglobin to methemoglobin. May cause eye damage – conjunctivitis, and skin – dermatitis. MPC for aerosol is 2 mg / m 3 . NFPA 704 Rating: Health Hazard: 2, Flammability: 1, Instability: 1.Carcinogenicity in animals with unknown relevance to humans has been confirmed.