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Bumps on skin from sun exposure: Sun allergy – Symptoms and causes

Polymorphic light eruption – NHS

Polymorphic light eruption is a fairly common skin rash triggered by exposure to sunlight or artificial ultraviolet (UV) light.

Symptoms of polymorphic light eruption

An itchy or burning rash appears within hours, or up to 2 to 3 days after exposure to sunlight.

It lasts for up to 2 weeks, healing without scarring.

The rash usually appears on the parts of the skin exposed to sunlight, typically the head, neck, chest and arms.

The face is not always affected.

The rash


ISM/SCIENCE PHOTO LIBRARY https://www.sciencephoto.com/media/520428/view

The rash can take many different forms (polymorphic):

  • you may get crops of 2mm to 5mm raised, pink or red spots, but redness may be harder to see on brown and black skin
  • some people get blisters that turn into larger, dry patches – it looks a bit like eczema
  • less commonly, the patches look like a target or “bulls-eye” (it looks a bit like erythema multiforme)

Polymorphic light eruption can be easily mistaken for heat rash (prickly heat).

Prickly heat is caused by warm weather or overheating, rather than sunlight or UV light.

The skin in prickly heat does not “harden” or desensitise, as it can do in polymorphic light eruption.

Polymorphic light eruption is thought to affect about 10% to 15% of the UK population.

Sunlight exposure

The rash may be a rare occurrence or may happen every time the skin is exposed to sunlight. It ranges from mild to severe.

Sometimes as little as 20 minutes of sun exposure is enough to cause the problem, and it can even develop through thin clothing or if you’re sitting near a window.

But for most people with polymorphic light eruption, the rash develops after several hours outside on a sunny day.

If further sun is avoided, the rash may settle and disappear without a trace within a couple of weeks.

It may or may not return when skin is re-exposed to sunlight.

If the skin is exposed to more sunlight before the rash has cleared up, it’ll probably get much worse and spread.

For many people with polymorphic skin eruption, the rash appears every spring and remains a problem throughout summer before settling down by autumn.

Who’s affected

Polymorphic light eruption is more common in women than men.

It particularly affects people who have white skin, although it can also affect those with brown and black skin.

It usually starts between the ages of 20 and 40, although it sometimes affects children.

Causes of polymorphic light eruption

Polymorphic light eruption is thought to be caused by UV light altering a substance in the skin, which the immune system reacts to, resulting in the skin becoming inflamed.

It’s not passed down through families, but about 1 in 5 people with the condition have an affected relative as it’s a fairly common condition.

It’s not infectious, so there’s no risk of catching polymorphic light eruption from another person.

Treatments for polymorphic light eruption

There’s no cure for polymorphic light eruption, but using sunscreens and careful avoidance of the sun will help you manage the rash.

Avoid the sun, particularly between 11am and 3pm when the sun’s rays are at their strongest, and wear protective clothing when outdoors (unless your doctor has advised you to try hardening your skin).

Introduce your skin to sunlight gradually in the spring.


You may be prescribed sunscreens to help prevent the rash developing.

Use a sunscreen that is SPF 50 or above with a UVA rating of 4 or 5 stars. Apply sunscreen thickly and evenly around 15 to 30 minutes before going out into the sun

Reapply every 2 hours and straight after you’ve dried yourself off after swimming.

Steroid creams and ointments 

A GP can prescribe corticosteroid (steroid) cream or ointment that’s only applied when the rash appears.

You should apply it sparingly, as often as the GP advises. Do not apply it when there’s no rash.

Desensitisation or UV treatment

It’s sometimes possible to increase the resistance of your skin to the sun.

This involves visiting a hospital dermatology department 3 times a week for 4 to 6 weeks in the spring.

Your skin is gradually exposed to a little more UV light every visit to try to build up your skin’s resistance.

The effects of desensitisation are lost in the winter, so you’ll have to build up your resistance again in the spring.

Hardening or toughening

A GP or dermatologist may advise you to try increasing the resistance of your skin at home.

This is known as “hardening” and involves going outside for short periods in the spring to build up your resistance.

You might find the time is as short as a few minutes at first, but you may be able to gradually build up to longer times.

You’ll have to be careful not to overdo it but, as you begin to understand more about how much light triggers your rash, you’ll be able to judge how long to stay out.

Like desensitisation, the effects of hardening are lost in the winter, so you’ll have to build up your resistance again in the spring.

Vitamin D

People with polymorphic light eruption are at greater risk of vitamin D deficiency, as a certain amount of sun exposure is needed to make your own vitamin D.

A GP can advise whether you need treatment with vitamin D supplements.


Many people with polymorphic light eruption find their skin improves over the years.

Your skin may harden (become more resistant to sunlight) during the summer, which means more sun can be tolerated without your skin reacting.

The rash may even eventually clear up on its own, although this is unusual.

Hardening of the skin does not always happen, and some people with very sensitive skin may even get the rash in the winter.

For these people, it may be a long-term condition to manage with lifestyle changes and creams.

Page last reviewed: 28 July 2021
Next review due: 28 July 2024

Heat rash, sun rash — what’s the difference?

Your skin sure does take the brunt of summer’s hot, humid and sunny weather.

Too much sun can cause a rash. Too much heat can cause a rash. But what’s the difference, how do you treat them and how do you avoid getting them?

Melinda Cooling, vice president of Advanced Practice Providers at OSF HealthCare and chief clinician executive for OSF Saint Gabriel Health, breaks it down for us.

Heat rash

Heat rash, also known as prickly heat, often occurs during hot, humid weather. This rash usually appears in areas where the skin folds or areas where clothes causes friction like armpits, elbow creases, or the groin area.

“This type of rash often is not related to sun exposure but rather when blocked pores trap sweat under the skin,” Melinda said. “A patient may have small blisters or a deep lump that can feel prickly or itchy.”

Other than the hot humid weather, heat rash can develop due to:

  • A lot of physical activity
  • Illness with fever
  • Tight or warm clothing
  • Bandages
  • Medicine patches that stick to the skin


“Most of the time, heat rash will resolve on its own by cooling the skin with cool compresses and avoiding exposure to the heat,” Melinda said.

Other treatment options may include:

  • Using a gentle exfoliator in the bath or shower
  • Corticosteroid cream or lotion to help reduce itching and inflammation
  • Antibiotic cream or lotion if bacteria is part of the cause
  • Drying powders

“If you would have increased pain, swelling, or redness around the affected area or a fever, it could be a sign of an infection and you should seek urgent care,” Melinda said.


Sometimes in the summer, to prevent heat rash may require changing clothes more frequently and keeping the skin cool and dry.

Other ways to prevent heat rash:

  • Wear lightweight, loose clothing
  • Wear fabric that lets air get to the skin, such as cotton
  • Remove bandages or patches

Sun rash

Sun rash starts in areas where the skin is exposed to sunlight.

“It usually presents as a red, itchy rash that groups together and it can feel like it is burning,” Melinda said. “Normally it shows within hours of the sun exposure. If the burn is severe, some patients may feel nauseated or feverish.”


Most sun rashes will resolve on its own within 10-14 days, she said.

“Over-the-counter aloe vera or anti-itch ointments can be helpful. Cool compresses or a cool bath can provide itch relief,” Melinda said. “If you have blisters, keep them clean and dry to help to prevent infection.”

If you have increased pain, fever, swelling or redness, you may have an infection and should seek urgent care, she said.


“The key to sun rash is prevention by using sunscreen with an SPF of at least 30 and to reapply the sunscreen every two hours or more often if you’re swimming or perspiring,” Melinda said. “Protect your skin with clothing and wear a wide-brimmed hat. Avoid the sun between 10 a.m. and 2 p.m. when the sun is most intense.”

Seek urgent care

 Whether you’re dealing with a heat rash or a sun rash and aren’t sure what to do, you can seek out urgent care at an OSF OnCall Urgent Care or OSF PromptCare clinic or go online and connect with a board-certified advanced practice provider at OSF OnCall.

Last Updated: May 22, 2023

View all posts by Lisa Coon

Tags: rash, skin care

Categories: General

Pimples on the skin of the face from the sun – what to do

Does your skin react strangely to ultraviolet light? Have you noticed that you get acne from the sun? Let’s figure out why this can happen and how to reconcile you with the sun’s rays!





sun protection



Do not self-medicate! In our articles, we collect the latest scientific data and the opinions of authoritative health experts. But remember: only a doctor can diagnose and prescribe treatment.

This unpleasant phenomenon can be found as many as five quite logical explanations.

First and most incredible: you suffer from a natural intolerance to ultraviolet rays. Scientifically, this disease is called photodermatitis. It is said that it was it that gave people with a rich imagination the ground for creating legends about vampires. In fact, “allergy to the sun” is a rather rare skin pathology, it manifests itself in only 2% of people around the world and requires specialized outpatient treatment.

The second, much more possible: you spend too much time on the beach, your skin becomes dry, and the sebaceous glands begin to behave unpredictably. Intense exposure to ultraviolet radiation leads to the fact that the pores become clogged with fat and dead cells. All this becomes inflamed over time and turns into red, inflamed pimples, often with purulent contents. What to do? Dose the time spent in the sun, sunbathe only during “safe” hours: before 10 am and after 4 pm. And in your case, it’s better not to abuse the solarium!


The third reason is related to the wrong choice of sunscreen cosmetics. It is important that milk or spray with UV filters not only protect against burns, but also suit your skin. If they are chosen incorrectly, then acne after the sun will appear, like an allergy to cosmetics. Most often, such reactions are observed as a result of using products with essential oils of sandalwood, musk, amber, tea tree, rosemary. But sometimes even completely harmless, at first glance, components can cause an undesirable effect. Choosing the right composition is usually necessary through trial and error.

Fourth, excessive sweating. It may well be that the true cause of inflammation is actually not the sun, but a reaction to it. If you sweat a lot on sunny warm days, then skin irritation is most likely due to this. On top of that, dust and dirt sticking to a sticky face and hands leads to the fact that the number of acne during the day increases exponentially. There is only one way out – to use wet wipes more often, to dress as lightly as possible, to choose clothes from natural breathable fabrics.

Finally, the fifth reason is the increased sensitivity of the skin, which is often caused by taking certain medications. If you are sick and have to take antibiotics – especially from the tetracycline and fluoroquinolone groups, or drugs from the sulfonamide category, then in the near future it is better to refrain from intense sunbathing.

Do pimples on your skin from the sun cause you a lot of problems and grief? There is only one way out: to correctly establish the true cause of their appearance and come to grips with its elimination!

Allergy to the sun – photodermatitis (photodermatosis) and its prevention – St. Petersburg State Budgetary Healthcare Institution Dermatovenerological Dispensary No. 11

The sun’s rays not only warm us with their warmth in the spring and summer and delight us in winter, but also help strengthen the immune system. But, unfortunately, in some people, exposure to the open sun can cause an allergic reaction.

Allergy to the sun, photodermatitis (photodermatosis) are diseases caused by increased sensitivity of the skin to sunlight. This is not at all a rare occurrence. Statistics show that about 20% of people around the world experience this disease.

Sun allergy is actually photodermatitis or photodermatosis. The toxic or allergic effect of the sun is manifested by the interaction of solar (ultraviolet) rays with any substance that is on the skin (exogenous photodermatitis) or in the skin (endogenous photodermatitis).

Sun allergy in the form of exogenous photodermatitis

The most striking example of exogenous photodermatitis is the so-called meadow dermatitis. In the summer, during the flowering period, many meadow plants secrete special substances – furocoumarins, which are deposited on the skin when a person is in these places. With simultaneous exposure to ultraviolet radiation, some people who are sensitive to it may experience skin redness and vesicles (erythema, vesicles, bullae). The rash is accompanied by intense itching. In the future, long-term pigmentation remains on the affected areas of the skin.

Sun allergy or photodermatitis can also occur if a person who is sensitive to the sun puts on a cream or ointment, or uses perfume and deodorant before going out into the sun. Substances that make up various cosmetics or perfumes can react with ultraviolet rays and cause an allergic reaction. Such properties are, for example, eosin, which can be found in lipstick, and para-aminobenzoic acid (surfactant), which is part of some sunscreens. In addition, polyunsaturated fatty acids, retinoids, bergamot oil, St.

Fair-skinned people and young children, whose skin defense mechanisms are much weaker, are more likely to be allergic to the sun.

Photodermatitis is often caused by many drugs. This effect is possessed, in particular, by sulfonamides, barbiturates, chlorpromazine, some antibiotics (doxycycline, tetracycline), antihistamines, some cardiovascular agents (amiodarone, trazikor), cytostatics, some non-steroidal anti-inflammatory drugs (ibuprofen, aspirin), oral contraceptives.

In addition, an increased reaction of the skin to the sun’s rays appears when the skin is “weakened” by some additional effect – peeling, tattooing using cadmium salts.

Allergy to the sun in the form of endogenous photodermatitis

This group of photodermatitis includes rather rare diseases, in the development of which disturbances in the functioning of the body’s immune system, as well as various metabolic disorders (metabolism disorders) play an important role. Endogenous photodermatitis includes, in particular, porphyria, xeroderma pigmentosa, sun eczema, sun pruritus, Hydroa vacciniformia, polymorphic photodermatosis.

Typically, these reactions can proceed through two mechanisms: 1) phototoxic reaction and 2) photoallergic reaction. Phototoxic reactions are much more common than photoallergic ones.

How does sun allergy or photodermatitis usually manifest itself?

Main symptoms of photodermatosis:

  • redness and inflammation of the skin,
  • peeling skin,
  • often accompanied by intense itching and burning,
  • rashes can be in the form of folliculitis (pustules) or papules.

Often this condition does not develop immediately. Unlike a burn, it can occur several hours after you leave the beach, and in some cases even after returning from the resort. A phototoxic reaction can occur several hours after sun exposure, while a photoallergic reaction can occur even days after sun exposure.

Increased risk of sun allergy:

  • in people with naturally fair skin;
  • in pregnant women;
  • in young children;
  • a number of drugs can make the skin burn faster – including tetracycline antibiotics, sulfanilamide drugs, painkillers, etc .;
  • who have relatives with sun allergies. You are more likely to be allergic to the sun if you have a sibling or parent with a sun allergy;
  • also having atopic dermatitis or another type of dermatitis increases the risk of developing a sun allergy;
  • Some skin allergy symptoms are triggered when your skin is exposed to a certain substance and then to sunlight. Some common substances responsible for this type of reaction include fragrances, disinfectants, bleach, and even some of the chemicals used in sunscreens;
  • those who abuse solariums;
  • In addition, an allergic reaction from exposure to the sun can also develop in those who have performed cosmetic procedures using cadmium salts the day before (tattooing, chemical peeling).

Photosensitizers cause sun allergy

Some vegetables and plants can cause sun sensitivity when they come into contact with the skin. Mango peel, lime juice, parsnips, celery can cause temporary discolouration (darkening) of the area of ​​skin exposed to the sun. The main phototoxic fruits and vegetables are celery, carrots, rice, parsley, parsnips, and all kinds of citrus fruits. Therefore, before going to the beach, you should not eat oranges, tangerines or grapefruits. Swelling, redness and itching may occur on the surface of the skin, where there are drops of juice from these fruits. And the more active the sun, the more acute will be the reaction of the body.

Prevention of sun allergy (photodermatitis and photodermatosis)

Unfortunately, there are not many methods for preventing such allergies.

If you have very sensitive skin, make it a habit to sunbathe under an awning or umbrella. Avoid exposure to the sun during its peak hours (from 11:00 to 16:00). Protect yourself with a headdress and loose clothing made from natural fabrics: linen, cotton. Children have a very weak protective skin reaction, so babies under three years of age are generally not recommended to be in direct sunlight.

Use high-protection sunscreens from well-known brands at regular intervals of at least every two hours. Please note that the cream contains protection against UVB rays (SPF) and UVA rays (PPD) – they affect the occurrence of photodermatosis.

It should be noted that the wavelength plays an important role. Try not to go to resorts where the sun is especially strong.