Prickly heat (heat rash): symptoms, treatment, and prevention

Hot and humid conditions are ideal for developing prickly heat rash, but they’re not its only cause. Heat rash can be a byproduct of your self-care if you enjoy hot yoga, exercise frequently, or use steam rooms or saunas. Even adding your winter layers too prematurely or throwing an additional duvet onto the bed can trigger it. Here’s everything you need to know about prickly heat rash and what to do about it.

What is prickly heat?

Prickly heat rash is pretty aptly named. It’s a prickly, itchy, and sometimes stinging rash that develops on your skin as a result of heat. Also known as eccrine miliaria or heat rash, the condition occurs when your sweat glands become obstructed. Because of this, sweat is trapped in the skin, resulting in a skin rash.

There are three types of eccrine miliaria — miliaria crystallina, miliaria rubra, and miliaria profunda. The type of heat rash that develops depends on the part of the sweat duct affected, and each has a slightly different presentation.

Heat rash can sometimes be hard to self-diagnose as it can look like a number of other skin conditions and rashes. If you’re having trouble identifying or treating your skin issue, Maple can help. Maple is a virtual care platform that connects you with Canadian-licensed doctors and specialists. With Maple, you can get to the bottom of your skin dilemma by seeing a doctor or dermatologist online from your phone, tablet, or computer.

Who can develop prickly heat?

Under the right circumstances, anyone can develop prickly heat rash, but here are some of the most likely groups.

Newborns and babies are highly prone to heat rash because their sweat glands are just developing. Additionally, they’re also less able to control their internal body temperature. Add that to the tendency for new parents to overdress their little ones, and you’ve got the perfect conditions for developing heat rash.

Babies aren’t the only population with an increased risk for the condition though. Being on bedrest increases your odds of developing prickly heat rash. Remaining in place for long periods of time — like in one position in a bed — hampers air flow to the immobilized areas. Besides precipitating irritation, this also limits the flow of sweat off your body.

Being confined to bed can result in heat rash even under cool or air-conditioned circumstances. But hot and humid conditions — like being in a building without air conditioning in the summer — up its probability.

Additionally, being overweight or obese may amplify your chances of experiencing the condition. This is due to the rolls of skin these individuals are more likely to have. Since the skin folds between these rolls are more likely to retain moisture, rub against each other, and occlude sweat glands, they make prickly heat rash more likely.

What causes prickly heat?

When your body can’t expel your sweat properly through your sweat ducts, it becomes trapped in your skin. With nowhere else to go, this sweat can spread under the surrounding skin, triggering an itchy, inflamed rash.

Keep in mind that heat rash isn’t contagious. However, heat rash can spread all over the body. It can also be triggered by a fever.

Another common cause of heat rash is travelling to a hot and humid climate. In this case, the condition usually resolves as your body acclimatizes to the new weather.

While anything that obstructs the sweat glands can trigger heat rash, certain causes are especially notable. A big one tends to be wearing constricting or synthetic fabrics that don’t allow for air flow — especially during high-intensity exercise. Prolonged bed rest is another as bedding can function as a barricade blocking your body’s sweat glands. Lightweight bedding is one way to help prevent heat rash.

What are the symptoms of prickly heat?

As its name suggests, prickly heat typically causes a prickly or itchy sensation in the skin. With miliaria rubra, the rash manifests in small uniform bumps between 2 to 4mm — about the size of tiny glass beads. You’re most likely to find it in areas that experience a lot of friction like around the collar, under your arms or breasts, or in the creases of your knees and elbows.

Alternatively, heat rash can present as tiny, 1 to 2mm bumps resembling glass beads. This is the case with miliaria crystallina, which is most likely to crop up on the head, neck, and upper trunks of infants, and mainly on the trunk for adults.

Finally, miliaria profunda appears as 1 to 4mm bumps on the trunk and extremities. These can be either skin-coloured or red.

What does prickly heat look like?

Prickly heat rash can look slightly different depending on the person experiencing it. It often appears as small raised red bumps, although the redness of the rash on the skin may not be as obvious on black or brown skin, or darker skin tones. Alternatively, the rash can appear as clear, fluid-filled bumps, leading many to compare it to acne.

How can you prevent heat rashes?

Wearing loose-fitting, lightweight cotton clothing is one of the best ways of avoiding heat rash. Thick and synthetic fabrics are more likely to trap heat, leading you to sweat. To avoid heat rash on hot days or while exercising, focus on wearing light layers that you can remove as you heat up. You’ll also want to drink plenty of water to avoid dehydration.

Newborns and small babies are more vulnerable to heat rash and can’t tell you when they’re getting too hot. While fall weather can tempt you into breaking out your baby’s thick winter sleep sack, unless you’re camping they’re probably unnecessary. Most houses sit somewhere around 21°C (70°F). This means that even when the thermometer dips outside, your baby’s room is likely pretty comfortable.

To ensure your baby is warm enough, avoid touching their hands or face. Because of their distance from your baby’s core, these will feel cool to the touch even when your baby is perfectly comfortable.

Instead, place a hand on your little one’s back or belly. If these feel warm, there’s no need for another layer. It’s hard not to worry, but your baby doesn’t require more layers than you do.

To further avoid repeat heat rashes, consider doing the following:

• Limit your exposure to hot and humid conditions, including steam rooms and saunas
• Cool off after sweating or an intense exercise session with a lukewarm shower
• Seek out air conditioning or use a fan when it’s hot
• Treat fevers with antipyretic, or fever-reducing medications like acetaminophen or ibuprofen

How long does prickly heat usually last?

The good news is that prickly heat rash doesn’t stick around for that long. Your symptoms should resolve within a day or two. If they’re not markedly better after day four, consider speaking with a healthcare provider.

Can you get rid of prickly heat fast?

Because prickly heat rash can result in inflammation, soothing your skin is often a good start to addressing the condition. A great way to do that is by using a cooling compress, or by wrapping an ice pack in a towel and applying it to the affected area. You’ll also want to avoid scratching the rash if possible to help prevent infection.

Additionally, you can take an antihistamine. This will help to calm the swelling and reduce the itchy, prickly feeling that the rash brings. But, while you can minimize the worst of its effects, these strategies won’t get rid of prickly heat rash entirely. Luckily, the condition should clear up within a day or two.

What are the most common treatments for prickly heat?

In addition to ice and antihistamines, there are a few other ways to soothe the redness, itching, and discomfort of your prickly heat rash. These include:

• Taking an oatmeal bath — while keeping your heat rash dry is important, bathing in oatmeal is an exception. Oatmeal contains avenanthramides, which are compounds with anti-inflammatory and anti-itch properties that help to soothe your skin. Just make sure to gently pat yourself dry afterwards instead of rubbing off with a towel. Exposing your damp skin to friction can make your rash worse.
• Applying an over-the-counter (OTC) hydrocortisone cream — this can help to relieve the worst of your symptoms. If your symptoms are severe or the area of your rash is quite large, however, you may require a prescription hydrocortisone cream.
• Applying calamine lotion — this may help to calm the itching associated with your heat rash.
• Using aloe vera — this helps to soothe rashes caused by prickly heat. Aloe is often used for treating sunburns due to its cooling and anti-inflammatory properties, and despite being a gel-like substance, it won’t block your pores. This makes it safe for addressing prickly heat rash.
• Keeping the affected area dry and cool. Heat and friction got you here in the first place, and exposing your rash to them will only make it worse. Do your best to keep your skin cool and dry until it’s had the chance to heal. While you’re at it, avoid ointments or other topicals that will block your pores, as this may worsen the rash.

When to see a doctor for heat rash

Heat rash will usually disappear on its own within a few days. While it can be uncomfortable, you’re unlikely to need to see a doctor.

In certain circumstances, however, you should speak to a doctor about your prickly heat rash. These include if your rash isn’t getting better, or seems to be getting worse after day three or four, as it’s a possible sign that you’ve developed a secondary infection. Likewise, if your heat rash is extremely painful, it’s a good idea to see a healthcare provider. They may be able to prescribe hydrocortisone cream to clear it up quicker.

In young children or those who are immunocompromised, some symptoms may indicate a secondary infection. If your child has what looks like heat rash and any of the following, it warrants a visit with their healthcare provider:

• An accompanying fever
• Swelling around the rash
• Drainage of pus from the affected area
• Chills

Additionally, if your heat rash is accompanied by headache, dizziness, nausea or vomiting, or feeling very weak or thirsty, you may be experiencing heat exhaustion or heatstroke. While you can usually deal with heat exhaustion safely at home, heatstroke is a medical emergency and requires immediate intervention.

If you’re not sure whether you’re experiencing heat rash, it’s a good idea to speak to a dermatologist for clarification. Some skin cancers can appear as rashes in their early stages, making proper diagnosis crucial. While seeing a dermatologist can take months, with Maple, getting a dermatology consultation takes less than 24 hours. Even better, you don’t need a referral.

If you’re experiencing heat rash and need treatment and medical advice, reach out today. Put that stinging, itchy feeling to rest and go back to feeling comfortable in the skin you’re in.

This blog was developed by our team and reviewed by a medical professional. 

Cholinergic urticaria: Symptoms, treatment, and causes

Cholinergic urticaria (heat bumps) can occur when a person’s core body temperature rises. Possible causes include exercise, stress, weather, and eating spicy foods. Small, round, itchy papules appear that usually fade within an hour.

The lesions typically resolve without treatment between a few minutes and an hour later. They usually have no lasting effects, but some people may avoid exercise and other activities to prevent urticaria. In rare cases, however, a severe reaction may develop.

The word “cholinergic” refers to a part of the nervous system that controls muscle contraction, blood vessel dilation, and slowing of the heart rate.

In this article, we look at the signs and symptoms of cholinergic urticaria, why it happens, and how to treat or prevent it.

Cholinergic urticaria tends to appear soon after a person’s body heats up. It can occur anywhere but is more likely to affect the trunk or arms.

The lesions that occur with cholinergic urticaria usually:

• measure 1–5 millimeters (mm) across
• are small and numerous
• are round and raised
• are the same color as the person’s skin
• are itchy
• last from a few minutes to one hour

The rash may include any combination of the following features:

• itching or tingling at the onset of the rash
• burning or itching in areas affected by the rash
• areas of small wheals or raised bumps on the skin
• larger wheals that lead to more significant areas of swelling
• angioedema, or swelling of the deeper layers of the skin

In rare cases, heat bumps may be linked to other problems throughout the body, such as:

• headaches
• diarrhea
• heart palpitations
• abdominal cramps
• low blood pressure
• bronchospasm, a tightening of the muscles in the airways
• wheezing or shortness of breath
• asthma

In some instances, a person may develop anaphylaxis, a life threatening allergic reaction that needs emergency medical attention.

Anaphylaxis is a severe allergic reaction that can be life threatening. The symptoms develop suddenly and include:

• hives
• swelling of the face or mouth
• wheezing
• fast, shallow breathing
• a fast heart rate
• clammy skin
• anxiety or confusion
• dizziness
• vomiting
• blue or white lips
• fainting or loss of consciousness

If someone has these symptoms:

1. Check whether they are carrying an epinephrine pen. If they are, follow the instructions on the side of the pen to use it.
2. Dial 911 or the number of the nearest emergency department.
3. Lay the person down from a standing position. If they have vomited, turn them onto their side.
4. Stay with them until the emergency services arrive.

Some people may need more than one epinephrine injection. If the symptoms do not improve in 5–15 minutes, or they come back, use a second pen if the person has one.

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Cholinergic urticaria can result from any activity that causes excessive sweating.

Examples include:

• exercise
• hot baths
• sitting in a sauna or hot tub
• being in a warm room
• exposure to hot temperatures, such as hot weather
• having a fever
• being angry or upset
• stress
• eating spicy food
• consuming alcohol, in some cases

Experts believe the sweating process and a release of histamine contribute to the reaction, but they do not know precisely what happens.

The body tends to release in response to an allergic reaction.

To diagnose cholinergic urticaria, a doctor will likely consider the symptoms and ask the person what they were doing when they started.

In some cases, they may ask a person to take a warm bath or do some exercise to see how urticaria appears.

A doctor can inject a drug called methacholine into a person’s skin to see if cholinergic urticaria develops. However, they are unlikely to use this test as it cannot reliably diagnose or rule out cholinergic urticaria.

Treatment and management options vary between individuals.

They include:

• medications, such as:
  • antihistamine, for instance cetirizine (Zyrtec)
  • ketotifen (Zaditor), an antihistamine and asthma medication
  • danazol (Danocrine), an anabolic steroid, in some cases
  • Omalizumab (Xolair), an anti-IgE monoclonal antibody
  • beta-blockers such as propranolol, alongside other treatments
• lifestyle changes to avoid triggers, such as:
  • avoiding places and activities that warm the body
  • cutting out spicy foods
  • limiting alcohol consumption
• stress management techniques, if stress appears to contribute
• ultraviolet (UV) phototherapy

While treatment may help, it may not completely prevent cholinergic urticaria.

Some dietary choices may help reduce the risk of overheating the body’s core and therefore of developing cholinergic urticaria.

It may help to avoid:

• hot drinks
• spicy foods
• alcoholic drinks

What are some tips to reduce body heat?

In most cases, cholinergic urticaria is not serious. It often lasts 15–30 minutes, and the rash will fade on its own 90 minutes after starting the activity that triggered it.

Cholinergic urticaria often starts between the ages of 10 and 30 years and gradually stops happening over time.

Here are some questions people often ask about cholinergic urticaria.

How do you get rid of cholinergic urticaria?

The rash will fade after a person stops the activity that caused the reaction. Avoiding situations that lead to overheating and sweating can prevent it. This is not always possible, however, and doctors can prescribe medication to resolve or prevent a rash.

Should I worry about cholinergic urticaria?

In most cases, cholinergic urticaria goes away when the person stops the activity that caused it and does not have any serious effects. In some cases, however, a person may develop a more severe reaction. If the rash occurs with other symptoms, the individual should ask a doctor for advice. Severe swelling and breathing difficulty may be signs of anaphylaxis, a life threatening reaction that needs immediate medical attention.

What does cholinergic urticaria feel like?

A rash of small bumps can appear on the skin. They may be itchy, prickly, or burning. Sometimes, larger bumps or wheals may develop with more severe swelling.

How long does cholinergic urticaria last?

It usually passes within a few minutes to an hour. According to DermNet NZ, wheals usually last 15–30 minutes, and the overall rash should disappear 90 minutes after starting the activity that triggered it.

Cholinergic urticaria is a type of hives or skin reaction that occurs when the body temperature rises. Experts do not know precisely how it happens, but the sweating process may play a role.

People who experience frequent or long lasting symptoms may wish to speak to their doctor about ways to manage the condition.

If a person experiences other symptoms, such as breathing difficulty, they should seek immediate medical attention.

Treatment and diagnosis of prickly heat in St. Petersburg

Dermatology

A dermatologist treats diseases of the skin, mucous membranes, hair and nails. It will help in solving problems with a fungal infection, various neoplasms (moles, warts, papillomas) and rashes.

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• Cost of services
• Peculiarities of prickly heat in children and adults
• Where prickly heat appears
• Types of prickly heat
• How to treat prickly heat
• How to make an appointment

Heat prickly heat is a skin disease that occurs at any age. It is manifested by a small rash that appears in characteristic places, and is easily diagnosed upon examination.

Cost of services

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Doctor appointment

Select clinic. “Leninsky Prospekt” “Prospect of Enlightenment”

Select a servicePrimary appointment with a dermatovenereologistRepeated appointment with a dermatovenereologistLaging, drug treatment

Features of prickly heat in children and adults

The disease is provoked by external factors and often occurs in summer, when traveling to countries with hot climates and high humidity. Almost everyone knows what prickly heat looks like, but many mistakenly consider it a problem only for young children.

When overheated and in heat, all people experience increased sweating. In closed areas of the skin and in the folds, its evaporation slows down, the ducts of the glands are clogged and a “greenhouse effect” is created. As a result, foci of irritation appear with rashes, swelling, redness, burning and itching.

Where prickly heat appears

Prickly heat in newborns and infants of the first year, young children can be caused by excessive wrapping, imperfect thermoregulation, improper care of delicate skin, high temperature in ARVI. Rashes are localized on the body – the back and upper chest, neck, folds in the groin and armpits.

In adults, the disease provokes profuse sweating during warming compresses, wearing tight synthetic clothing in the heat, obesity, poor hygiene and endocrinological pathologies. Prickly heat appears on the legs and arms in the knee and elbow cavities, on the face – especially on the forehead in women when using dense creams.

Both office workers, who have to wear trousers in hot weather, and those who like skinny jeans, face the “sauna effect”. In this case, prickly heat in men occurs between the legs, in the anorectal region, on the scrotum and causes severe discomfort.

Do not confuse prickly heat with diaper rash, which also occurs in people of any age and gender and is often localized in similar places. They are provoked by prolonged exposure to moisture and friction, and there is no pronounced rash on the swollen, reddened skin.

Types of prickly heat

There are four forms of prickly heat, which differ in symptoms and duration.

Crystalline

Eruptions on the body (back, chest) in this type of prickly heat are very small blisters with a clear liquid. They are not accompanied by reddening of the skin, can appear even when overheated during physical exertion and disappear on their own after a couple of days.

Red

Small cloudy vesicles and nodules cover large areas of hyperemic skin. Affected areas may merge with each other. In constantly wet folds, inflammation is accompanied by burning. Red prickly heat occurs on the neck, armpits, groin, under the mammary glands and lasts up to two weeks.

Yellow and white

In this form, blisters with purulent contents appear, which indicates the addition of an infection, usually staphylococcal. The disease often develops as a result of ignoring prickly heat and complete blockage of the ducts, their rupture and infection. The treatment can take up to a month.

As a complication of miliaria, newborns may develop vesiculopustulosis. Eruptions appear in the upper back, in the folds of the skin, on the head. They quickly transform into pustules, which open themselves or become covered with a crust.

How to treat prickly heat

If the disease in the crystalline form can still be dealt with at home, but it is better to deal with the rest under the supervision of a specialist. With timely access to a doctor, the treatment of prickly heat does not take much time and relieves complications.

Comprehensive approach includes:

• Elimination of provoking factors – correction of skin care and hyperhidrosis, change of cosmetics and transition to natural fabrics.
• Selection of drugs for the treatment of prickly heat – ointments, antiseptics, powders, creams.
• When rashes appear, you need to contact a dermatologist who will determine their cause and knows how to get rid of prickly heat of any form. This will help to avoid the development of a strong inflammatory process, infection and the appointment of antibacterial agents.

How to make an appointment? Kirovsky (Boulevard Novatorov, 11, telephone for communication).

Reception conducted by:

Pavlova Natalia Nikolaevna

Dermatovenereologist of the highest qualification category
Clinic on Novatorov boulevard

Dik Alla Anatolyevna

Dermatovenereologist/oncologist
Clinic on Engels Ave.

Prickly heat in adults: causes and symptoms.

How to get rid of prickly heat?

One of the main functions of the skin is to protect the body from adverse environmental influences. The appearance of various rashes, redness, vesicles indicates a violation of the integrity of the epidermis and the development of skin diseases. Among the most common ailments include prickly heat. When contacting a doctor, the main desire of patients is the desire to learn about the causes of such manifestations, and of course, how to get rid of them.

Prickly heat in adults: causes

Prickly heat is most often registered in the hot season. It is with overheating that the mechanism of occurrence of skin rashes is associated. Prickly heat is a consequence of the protective reaction of the body. When overheated, the skin opens the pores for better heat transfer, and the sweat glands begin to work actively, releasing fluid – sweat for cooling. Sweat contains a set of salts that have a crystalline form. By themselves, salts can be an irritant, exacerbating the situation and their form.

Irritation is formed gradually, salt molecules penetrate into open pores, irritating the epidermis from the inside, which causes redness and itching. After some time, bubbles with transparent contents may appear on the surface of the skin.

What does prickly heat look like?

Miliaria most often occurs in closed areas of the body, such as the armpits, groin, inner thighs, etc. The symptoms of prickly heat are redness of the skin. With a simple form, they disappear by themselves within 24 hours.

Physicians distinguish several forms of this disease. Symptoms of crystalline prickly heat are the appearance of white or pearly bubbles of small diameter. The rash itself can be quite extensive and merge with each other. With mechanical contact, the bubbles open easily, after some time peeling forms on this affected area.

Red prickly heat is characterized by the formation of small uniform vesicles or nodules. Around them, areolas of reddened skin appear – hence the name. With red prickly heat, the elements of the rash do not merge with each other.

Skin areas with rash are sensitive and may cause pain and itching when touched. With high humidity or high temperatures, symptoms may worsen.

Deep prickly heat is characterized by the appearance of a skin-colored skin rash of small diameter. It most often forms on the skin of the trunk, but can appear on the arms and legs. This type of prickly heat is more typical for adults living in places with a humid climate.

How to get rid of prickly heat?

To treat and even relieve the symptoms of prickly heat, you need to see a doctor. Only in this case, the entire list of medical care will be provided, with well-chosen drugs and useful tips. With self-treatment of prickly heat in adults, there is a high risk of starting the process and provoking the appearance of complications.

Complications of prickly heat include the addition of a secondary infection. In this case, the symptoms of prickly heat intensify, pain appears. The elements of the rash also change.

If prickly heat appears for the first time, then it is necessary to reconsider your approach to personal hygiene. Not only the frequency of showering, but also cosmetics can cause illness. It is best to give preference to products with a neutral pH.

1. Walnut baths can be used as traditional medicine. To prepare a decoction, you need to chop the walnut leaves and brew with boiling water.
2. For the treatment of prickly heat, medicinal herbs can be used – chamomile, string, celandine, horsetail, mint, oak bark, etc. To prepare a decoction, brew chamomile and string in equal proportions.
3. Bay leaf can also be used to treat prickly heat. To prepare a solution for applications, it is necessary to use 5 – 7 dry bay leaves, which must be brewed with 1 tbsp. boiling water. With this solution, you can wipe the reddened areas of the skin or make lotions.

Prickly heat: methods of treatment

Drug treatment of prickly heat, involves the use of various powders and ointments. Prickly heat in the face area is effectively stopped with the help of zinc ointment, which has an anti-inflammatory effect and has a drying effect. The ointment must be applied to clean and dry skin up to 6 times a day.

Zinc is also contained in “Calamine”, which has an anti-inflammatory effect, perfectly relieves itching by cooling the skin. You can use powders containing talc and zinc oxide.

For the care of the skin in areas of favorite occurrence of prickly heat and excessive sweating, you can use powders that are recommended for children’s skin.

All persons suffering from prickly heat are advised to wear loose-fitting clothing made from natural, breathable materials. It is worth fearing overheating of the body, do not visit baths and saunas. Excess weight can be a provoking factor in the formation of prickly heat. According to statistics, obese people are most susceptible to these rashes, regardless of the time of year and weather conditions.

In hot weather it is recommended to drink as much water as possible. This will help to reduce the concentration of salts in the released sweat, and, accordingly, reduce irritation. In case of excess weight, frequent occurrence of prickly heat, it is necessary to consult an endocrinologist to exclude thyroid disease.

See also:

• Newborn skin rash: causes
• Why do hands sweat?
• How to treat diathesis?
• What to do if feet sweat?
• Rash on the face of an adult: causes

It is best to avoid unpleasant symptoms such as prickly heat. To do this, you must follow a number of rules. The best prevention is the implementation of all hygiene measures, regular air and sunbathing. Fat people who are prone to rashes need to think about measures to reduce excess weight, since it can be the main cause of prickly heat.