Polymorphic Light Eruption or Sun Allergy

Polymorphic Light Eruption or Sun Allergy

Your immune system reacts to sunlight as if it’s harmful.

Polymorphous light eruption is a rash caused by sun exposure in people who are sensitive to sunlight. Polymorphous means that the rash can have many forms, such as tiny bumps, raised areas or blisters. The condition also is called sun allergy, sun poisoning and polymorphic light eruption.

The reaction usually happens during spring and early summer when exposure to sunlight increases. 

The rash that results from polymorphous light eruption can look different from person to person but typically includes inflammation, itching and small bumps that may be densely packed together.

Symptoms: Itchy, red blotches, often on chest, arms, or legs. Sometimes hives.

In polymorphous light eruption, eruption refers to the rash, which usually appears 30 minutes to several hours after sun exposure. The rash usually appears on areas of the body that are covered during winter but exposed in summer such as the upper chest, front of the neck and arms.

With polymorphous light eruption, sensitivity to sunlight lessens with repeated exposure. Features of polymorphous light eruption are somewhat predictable:

• An episode is most likely to occur after the first one or two times of sun exposure after a long period of no exposure, such as in spring or early summer.
• Episodes are less likely to happen as the summer progresses.
• After the first episode, it's likely to happen each year. Some people gradually become less sensitive over several years and eventually no longer experience the yearly rash.