How long does a sun allergy last?

Sun allergy is triggered by exposure to ultraviolet radiation from the sun. It can take three main forms, solar urticaria, chemical photosensitization, and polymorphic light eruption. Most symptoms resolve on their own, but sometimes treatment is needed.

1. What are the symptoms of sun allergy

People with photosensitivity develop skin symptoms on exposed areas of the body. There are three types of sun allergy:

solar urticaria: large, itchy red bumps or scratches (dermatosis);

chemical photosensitization: inflammation, painful redness, and temporary and abnormal pigmentation (brown or bluish) in case of phototoxicity. Presence of scaling, redness, itching, or blistering if photoallergy;

polymorphous light eruption: red bumps, reddish patches, itching, or even blisters.

2. Duration of sun allergy

Usually, symptoms eventually subside on their own within hours, days, or weeks. How quickly these symptoms resolve depends on the type of sun allergy:

For solar urticaria: The reaction starts within minutes and stops quickly, within minutes or hours. Hives may recur regularly over a long period of time or even throughout life.

For phototoxicity: The reaction is caused by certain drugs or chemicals ingested/applied to the skin. Symptoms occur a few hours after sun exposure and may disappear when contact with the causative substance is stopped.

If photoallergy is present: Symptoms occur 1 to 3 days after sun exposure, when certain products (aftershave lotions, sunscreens, sulfonamides) are in contact with them. Disappearance is slow, with possible subsequent reappearance.

In polymorphous light eruption: Symptoms appear within minutes, hours, or days and may resolve within hours or days. Lucitis is a chronic, recurring allergy.

If the allergy persists, doctors look for possible causes using skin patch tests and may prescribe treatment (antihistamines, corticosteroids, sunscreens, ultraviolet phototherapy).