Sun allergy: why does the skin react to the sun and how to protect yourself?
Sunlight is essential for life, but in some people it can cause an adverse skin reaction. Although a “sun allergy” is not a true allergy in the strict sense of the word, some people are hypersensitive to the sun’s ultraviolet (UV) rays. In such cases, skin rashes, itching, redness, or an inflammatory reaction of varying severity may develop after sun exposure.
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Sun rash is the immune system's response to exposure to ultraviolet radiation, resulting in an itchy rash, small bumps, or spots on the skin.
What is polymorphic light eruption (PMLE)?
There are several forms of "sun allergy," but the most common is Polymorphous Light Eruption (PMLE).
PMLE is an autoimmune skin reaction that develops after exposure to sunlight. In this condition, ultraviolet rays activate certain cells of the immune system, which mistakenly attack their own skin cells. This results in inflammation of the skin.
PMLE is about a type of skin rash caused by sunlight. It is 70%It can develop in both women and men and in people with any skin type.
It most often first appears in adolescence or young adulthood.
Risk factors for developing PMLE include:
- Genetic predisposition
- Female gender
- Light-colored skin
- Living in northern regions, where the skin is less accustomed to intense sun exposure
Other forms of sun allergy
Solar Urticaria (Solar urticaria)
This condition causes a hives-like rash on the skin — red, itchy, raised spots or nodules.
The reaction can develop within minutes of exposure to the sun, but sometimes it can take anywhere from 30 minutes to 2 hours.
Actinic Prurigo (Actinic prurigo)
This is a relatively rare form of sun allergy that appears on areas exposed to sunlight.
Characteristic:
- Small size
- Very itchy
- Bumpy rash (papules and nodules)
Actinic prurigo is more common in people who have a history of eczema or atopic dermatitis.
Photoallergic reaction and drug-induced photosensitivity
In some cases, sunlight reacts with substances applied to the skin or ingested into the body.
For example, ultraviolet rays may change:
- Some medications
- Cosmetics
- Structure of other chemicals
The body perceives this altered substance as foreign and an allergic reaction develops.
which medications increase sensitivity to the sun?
Some medications can increase the skin's sensitivity to UV rays. However, taking them does not automatically mean that a person will develop a sun rash.
The groups of medications associated with photosensitivity are:
- Antibiotics
- Antifungal drugs
- Antihistamines
- Cholesterol-lowering medications
- Diuretics
- Nonsteroidal anti-inflammatory drugs (NSAIDs)
- Oral contraceptives and estrogen-containing drugs
- Phenothiazine
- Psoralens
- Retinoids
- Sulfonamides
- Sulfonylurea group drugs
If you are taking any of these medications, it is advisable to discuss additional sun protection measures with your doctor.
What does PMLE look like?
Polymorphous Light Eruption (PMLE) often appears in spring or early summer, after the first intense sun exposure of the season.
The rash usually develops:
- In a few hours
- For a few days
The most commonly affected areas are those that are covered with clothing in the winter and exposed to the sun in the summer:
- Neck;
- Upper chest
- Outer surface of the arms
Symptoms may include:
- Reddish spots
- Itching
- Burning or tingling sensation
- Small knots
- Bubbles
- Areas of scaly or rough skin
Sometimes the rash can have a target-like shape (erythema multiforme-type lesions).
In most cases, Polymorphous Light Eruption (PMLE) does not leave a scar.
In severe cases, the following may develop:
- Widespread skin rash
- headache
- Fever
- Fatigue
- Decreased blood pressure
In case of such symptoms, you need to consult a doctor.
How long does a sun rash last?
Polymorphous Light Eruption (PMLE) is often a self-limiting condition—symptoms usually resolve within a few days if sun exposure is avoided.
Often the rash persists 2–3 daysHowever, in some cases, especially in more severe cases, it may last for several weeks.
How is sun allergy treated?
The main principle of treatment is to reduce exposure to sunlight and protect the skin.
Sun protection
It is recommended:
- Limiting sun exposure, especially between 10:00 a.m. and 16:00 p.m.
- Using long-sleeved clothing
- Wearing a wide-brimmed hat
- Using sunglasses
- Being in the shade
It is important to remember that sunlight reflected from the surface of the water increases the exposure to UV radiation.
Sunscreen
Use:
- Broad-spectrum sunscreen with SPF 30 or higher
- A product that protects against both UVA and UVB rays
Sunscreen:
- Apply before going out in the sun.
- Update approximately every 2 hours
- Reapply after swimming or heavy sweating.
If you have sensitive skin, choose a product specifically designed for this type of skin.
Medical treatment
For Polymorphous Light Eruption (PMLE), your doctor may prescribe:
- Steroid creams — To reduce inflammation, itching, and redness
- Antihistamine drugs — To relieve itching
- In severe cases — short-term steroid tablets
- Immune-suppressing drugs (e.g., azathioprine) — in selected cases
Sometimes used:
- Hydroxychloroquine — for the prevention of exacerbations;
- Polypodium leucotomos extract — As antioxidant and anti-inflammatory support.
Treatment selection should be made by a dermatologist.
How is sun sensitivity diagnosed?
If necessary, the doctor may prescribe:
Patch test
A specific substance is placed on the skin and the skin reaction is assessed.
Photopatch test
The substance on the patch is pre-exposed to UV rays to assess the photoreaction.
Phototest
A small area of skin is exposed to UV rays and the reaction is assessed.
Photoprovocation test
A small area of skin is exposed to UV light and then a specific substance is applied.
These studies should only be conducted by a specialist with appropriate qualifications.
Self-care methods to relieve symptoms
Maybe you can help:
- Cold compresses
- Hydrocortisone 0.5–1% cream
- Antihistamine drugs
- Painkillers (for example, ibuprofen or paracetamol)
- Aloe products
- Getting enough fluids
When should you see a doctor?
It is necessary to consult a doctor if:
- The rash is painful.
- Interferes with sleep or daily activities
- Spreads over a large part of the body
- Has signs of infection
- Does not disappear within 10–14 days
Also contact your doctor if you develop:
- Fever
- Chills
- Nausea
- Vomiting
- Dizziness
Because sun rash can resemble other photodermatoses, a differential diagnostics by a specialist is sometimes necessary to select the correct treatment.
Order all analyses online
Source:
https://www.health.harvard.edu/blog/recognizing-and-preventing-sun-allergies-202207052772
https://www.thewellnesscorner.com/blog/detect-and-manage-sun-allergies
https://www.verywellhealth.com/sun-rash-8742965
