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Dr. Chrysoula I. Liakou MD, PhD
- Treated online: Yes. A sun allergy rash is recognised by how it looks and when it appeared, and a doctor can assess it on camera.
- What it is: polymorphic light eruption, an itchy rash a few hours to 2 days after strong sun, most often in spring, early summer or on a sunny holiday.
- Usual course: it usually fades in about a week if you stay out of the sun, and it heals without scarring.
- Prevention: shade, covering clothing and a sunscreen of SPF 50 or more with high UVA protection; the skin usually adjusts as the summer goes on.
- Emergency: call 112 for swelling of the lips, mouth or throat, or difficulty breathing.
Do not book a video appointment if a rash comes with swelling of the lips, mouth, tongue or throat, difficulty breathing or swallowing, or sudden dizziness or confusion, or if someone in the heat becomes confused, faints or has hot skin that has stopped sweating. These need emergency care: call 112.
Can an online doctor treat a sun allergy?
Yes. A sun allergy rash is recognised by how it looks, where it is and when it appeared, and all three work by video. The doctor looks at the rash on camera, asks about the sun exposure before it, and checks for other causes, such as a medicine that makes skin sensitive to light. Most sun allergy rashes settle with time out of the sun, and the doctor can prescribe treatment for a severe or recurring rash.
How an online consultation helps with a sun allergy
- The rash seen on camera: The doctor looks at the spots, blisters or patches, where they are, and how they look on your skin tone.
- Other causes ruled out: Heat rash, sunburn, hives and reactions to medicines or products in sunlight can look similar, and some need different treatment.
- Relief for the itch: Antihistamines, soothing lotions or a steroid cream, chosen after the doctor checks your other medicines.
- A plan for the rest of the summer: How to protect your skin, when to go back in the sun, and how to prepare for next year.
What the doctor checks in an online sun allergy consultation
The consultation follows a fixed order, and the warning signs come first. The doctor asks about:
- Warning signs: swelling of the lips, mouth or throat, breathing difficulty, a fever, or blistering over a large area.
- The rash: how long after the sun it appeared, where it is, whether it itches or burns, and whether it has happened before.
- The sun: where you were and for how long, and whether the rash followed sun through a window or on a cloudy day.
- Medicines and products: new medicines, creams, perfumes and sunscreens, which can cause reactions in sunlight.
- Other symptoms: joint pain, muscle pain or extreme tiredness, which need further checks.
Before the call, keep the rash out of the sun, and find good light indoors so the doctor can see it clearly.
What is a sun allergy?
Sun allergy is the everyday name for polymorphic light eruption (PLE), a rash caused by a reaction to sunlight. It is mainly triggered by UVA light, which passes through window glass. It cannot be caught or passed on.
PLE is most likely when strong sun reaches skin that has seen little of it for months: in spring and early summer, or in the first days of a sunny holiday. It is more common in women, in people under 40 and in people with fair skin, but it affects all skin types.
How common is a sun allergy in Europe?
Very common: it is the most common rash caused by UV light. In a survey of 6,895 people in six European cities, 18% had had polymorphic light eruption at some point in their lives. Women were affected nearly three times as often as men, and the rash was not more common further north: the highest rate was in Athens.
Swipe sideways to compare →
| City | Country | People who had had it |
|---|---|---|
| Athens | Greece | 19.5% |
| Heidelberg | Germany | 18.9% |
| Besançon | France | 17.5% |
| Manchester | United Kingdom | 17.3% |
| Leiden | Netherlands | 17.0% |
| Turku | Finland | 13.6% |
It usually starts before the age of 30, and it runs in families: about 15% of people with PLE know of a relative who has it.
Sun allergy symptoms
The rash usually appears a few hours to 2 days after time in strong sun:
- small raised spots or blisters, or larger blotchy patches
- itching or burning
- red or pink skin on white skin; on brown or black skin the rash can be harder to see
It often appears on skin that is usually covered, such as the arms, the legs and the chest. It usually fades in about a week if you stay out of the sun, and heals without scarring. With more sun it can last longer, get worse or come back.
How do you know if you have a sun allergy?
Usually from the rash and its timing alone: an itchy rash that appears hours to days after strong sun and fades within about a week out of the sun points to PLE. When the picture is unclear, a dermatologist can confirm it:
- Phototesting: a small area of skin is exposed to UV light under supervision to bring out the rash, and about 60% of people with PLE react.
- Blood tests: a blood count and an antinuclear antibody test help rule out lupus, which can also cause a rash in sunlight.
- A skin biopsy: occasionally, to exclude other conditions.
Is a sun allergy an autoimmune disease?
It is an immune reaction rather than a classic autoimmune disease. PLE is a delayed reaction of the skin’s immune system to substances that sunlight produces in the skin, which is why the rash takes hours to days to appear. Lupus is an autoimmune disease that can also cause a rash in sunlight, and joint pain, muscle pain or extreme tiredness with the rash are reasons for tests.
Sun allergy, heat rash or something else?
Several summer rashes look alike. These patterns help tell them apart:
Swipe sideways to compare →
| Rash | What points to it | Read more |
|---|---|---|
| Sun allergy (PLE) | Itchy spots or patches hours to 2 days after strong sun, on sun-exposed skin; fades in about a week out of the sun | This page |
| Heat rash | Tiny prickly spots where you sweat, even in the shade | Heat rash |
| Sunburn | Hot, red, painful skin within hours of the sun, wherever the sun reached | Sunburn |
| Hives | Raised welts that come and go within hours; sunlight is a rare trigger | Hives |
| A medicine reaction in sunlight | A rash or an exaggerated burn on sun-exposed skin after starting a new medicine | Tell the doctor about new medicines |
| Lupus | A rash in sunlight with joint pain, extreme tiredness or feeling generally unwell | Needs blood tests |
How to treat a sun allergy rash
Most sun allergy rashes clear on their own within a week once the skin is kept out of the sun. To ease the symptoms:
- Stay out of the sun, or keep the rash covered, until it has faded.
- Take an antihistamine tablet for the itch; a pharmacist can suggest one.
- Use calamine lotion or an emollient to cool and soothe the skin.
- Avoid scratching, which can break the skin.
How to prevent a sun allergy rash
Prevention works best when it starts before the first strong sun of the year:
- Stay out of the sun in the middle of the day, between 11am and 3pm, when it is strongest.
- Use a broad-spectrum sunscreen with an SPF of 50 or more and high UVA protection. Apply it 15 to 30 minutes before going out, and again every 2 hours and after swimming.
- Wear a sun hat and loose clothing that covers your arms and legs.
- Sit away from windows on bright days, because UVA light passes through glass.
- Give your skin short, gradually longer spells of sun early in the season. The skin adjusts as the summer goes on, which is why the rash becomes less likely later in the year.
To see how strong the sun is where you are going, check the daily UV scores for European cities in the Climate Health Index.
Which sun allergy treatment might the doctor recommend?
Treatment depends on how severe the rash is and how often it comes back. This is the framework the doctors use, in line with NHS and dermatology guidance.
Swipe sideways to compare →
| What you have | Likely first step | Suitable for online care? | When in-person care is needed |
|---|---|---|---|
| A mild, itchy rash after the sun | Time out of the sun, an antihistamine, calamine or an emollient | Yes | Not usually needed |
| A rash that is worse, or no better after a week | A steroid cream, and a review of the diagnosis | Yes | If the doctor needs to examine it |
| A rash every spring or every sunny holiday | A prevention plan; sometimes light therapy in spring or a short course of steroid tablets | Yes, to plan | For light therapy, which is given by a dermatologist |
| A rash with joint pain, muscle pain or extreme tiredness | Tests for other causes, such as lupus | Partly | For blood tests or a specialist review |
| Swelling of the lips or throat, or breathing difficulty | Emergency treatment | No | Call 112 now |
Not sure the sun caused your rash? A doctor can tell you in one consultation.
See available times →Treatment options for a sun allergy
What you can do yourself
- Keep the rash out of the sun, or covered, until it fades.
- Take antihistamine tablets from a pharmacy for the itch.
- Use calamine lotion or an emollient to cool the skin.
- For the rest of the trip, use a high-SPF sunscreen with high UVA protection, and cover up.
Prescription treatment
A prescription is never issued without a consultation. For a rash that is severe or not improving, the doctor may prescribe a steroid cream. If the rash comes back every year, a dermatologist can offer light therapy in early spring to prepare the skin for summer, and for some people a short course of steroid tablets is used during a flare or before a sunny holiday. For a rash that returns every year despite this, dermatologists sometimes use hydroxychloroquine through spring and summer, or nicotinamide, a form of vitamin B3, started 2 to 4 weeks before the usual season. No medicine cures PLE. If the doctor prescribes, use the prescription at a pharmacy near you.
What does not help
Staying in the sun with the rash makes it last longer. Sunscreen alone, without shade and clothing, does not always prevent it, because some sunscreens protect poorly against UVA light.
Special situations
Sun allergy on holiday
The rash often appears in the first days of a sunny holiday, after months with little sun. Cover up and use the shade for a few days, protect your skin with a high-SPF sunscreen, and give it time to adjust before longer spells in the sun. Other holiday health problems are covered on the travel illnesses page.
Sun through windows
UVA light passes through window glass, so the rash can appear after a long car journey or a day by a sunny window.
Medicines that react with sunlight
Some medicines can cause a rash or an exaggerated burn in sunlight. If a rash appears after starting a new medicine, tell the doctor rather than stopping it.
Vitamin D if you avoid the sun
People who avoid the sun because of PLE can run low on vitamin D. Ask the doctor about checking your level, and about a supplement if it is low.
Will it go away for good?
PLE can return every year, but it often eases with time: about 60% of people improve or clear over 15 years, and it tends to be less frequent and milder after the menopause.
Children
Mobi Doctor consultations are for adults aged 18 and over. A child who is unwell needs a paediatrician or a local doctor in person, and emergency signs in a child mean 112.
When a sun allergy is treated online, and when you need in-person care
Treated online: sun allergy rashes, itchy rashes after a sunny holiday, rashes that come back each spring, and planning prevention for the next trip.
In-person care: a rash with swelling of the face or throat or breathing difficulty, blistering over a large area, light therapy, and blood tests when another cause, such as lupus, is possible.
When to get in-person care
Call 112 or go to an emergency department now for:
- sudden swelling of the lips, mouth, tongue or throat
- very fast breathing, difficulty breathing, or a tight throat
- sudden confusion, drowsiness or dizziness, or fainting
- confusion, fainting or hot skin that has stopped sweating after time in the heat
Get medical advice the same day for:
- a rash that is spreading fast or blistering over a large area
- a rash with a high temperature and feeling unwell
- swelling under the skin
How Mobi Doctor works
- Book a time that suits you: daily 7am–11pm CEST. You can see a doctor over video, usually within 15 minutes. No subscription, and the exact price is shown before you pay.
- Speak to a licensed doctor about the rash: show it on camera in good light, and say when you were in the sun and when the rash appeared.
- Leave with a plan: what to do, what to take and for how long, and which signs mean you should be seen in person. If the doctor prescribes, use the prescription at a pharmacy near you.
No sign-up needed
Not sure it’s a sun allergy? Tick every symptom you have to see each condition page that mentions it. It finds the right page, not a diagnosis: a doctor gives you that on a video call.
Tap the body — an area or a point — to browse symptoms anywhere
Similar symptoms, different condition? Heat rash can start the same way. Compare them, or look up any other symptom in the full symptom checker.
Frequently asked questions about sun allergy
What does a sun allergy rash look like?
A sun allergy rash, polymorphic light eruption, is made of small raised spots or blisters, or larger blotchy patches, that itch or burn. It is red or pink on white skin and can be harder to see on brown or black skin. It often appears on the arms, the legs and the chest.
How long does a sun allergy rash last?
A sun allergy rash usually fades in about a week if you stay out of the sun, and heals without scarring. It lasts longer, or comes back, if the skin keeps getting strong sun.
What is the fastest way to get rid of a sun rash at home?
Keep the sun rash out of the sun, take an antihistamine for the itch, and use calamine lotion or an emollient to soothe it. A doctor can prescribe a steroid cream for a severe rash.
Why do I get a sun rash on holiday?
Polymorphic light eruption is most likely when strong sun reaches skin that has had little sun for months, as in the first days of a holiday in the south or in early summer. The skin usually adjusts as the summer goes on.
Which sunscreen is best for a sun allergy?
For a sun allergy, use a broad-spectrum sunscreen with an SPF of 50 or more and high UVA protection, applied 15 to 30 minutes before going out, every 2 hours and after swimming. Combine it with shade, a hat and covering clothing.
Can you get a sun allergy through a window?
Yes. The sun allergy rash is mainly triggered by UVA light, which passes through window glass, so it can appear after a long car journey or a day by a sunny window.
How common is a sun allergy?
Very common. In a survey of 6,895 people in six European cities, from Athens to Turku, 18% had had polymorphic light eruption at some point. It was not more common in the north, and women had it nearly three times as often as men.
Is polymorphic light eruption an autoimmune disease?
It is an immune reaction rather than a classic autoimmune disease: a delayed reaction of the skin’s immune system to substances sunlight produces in the skin. Lupus, an autoimmune disease, can also cause a rash in sunlight, so joint pain, muscle pain or extreme tiredness with the rash need blood tests.
Does vitamin D deficiency cause a sun allergy?
PLE is caused by a reaction to sunlight. The vitamin D link usually runs the other way: avoiding the sun to prevent the rash can lead to low vitamin D, so ask a doctor about checking your level and a supplement if it is low.
Will my sun allergy go away?
It can come back every spring, but it often improves over the years: about 60% of people get better or clear over 15 years, and it tends to be milder after the menopause. Light therapy in spring helps some people whose rash returns every year.
Can an online doctor treat a sun allergy?
Yes. A doctor can look at the sun allergy rash on camera, tell it apart from heat rash, sunburn and medicine reactions, and recommend treatment. If the rash is severe or keeps coming back, the doctor can prescribe a steroid cream after the consultation.
- Polymorphic light eruption, NHS, National Health Service (UK), reviewed 10 June 2025.
- Polymorphic light eruption, DermNet, New Zealand, May 2022.
- Polymorphic light eruption (PLE), British Skin Foundation, accessed 15 October 2026.
- Lifetime prevalence and characteristics of the ‘sun-allergy’ polymorphic light eruption in Europe, Bock M, Janssens AS, Rhodes LE et al., in Janssens AS, doctoral thesis, Leiden University, 2008.
- Sunscreen and sun safety, NHS, National Health Service (UK), reviewed 24 March 2026.
- Hives, NHS, National Health Service (UK), reviewed 26 April 2024.
This page is for information only and is not a substitute for a medical consultation. Guideline links are provided for transparency; treatment decisions are made with your doctor.
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