Polymorphic light eruption

Polymorphic light eruption causes red papules in a rash on the skin after even brief exposure to sunlight, or in some cases after exposure to artificial fluorescent light.

Image credit: Color Atlas of Pediatric Dermatology
Samuel Weinberg, Neil S. Prose, Leonard Kristal
Copyright 2008, 1998, 1990, 1975, by the McGraw-Hill Companies, Inc. All rights reserved.

The term 'polymorphous' refers to the fact that the rash can take many forms. This includes groups of pink or red raised spots on the arms. Other areas, including the legs and chest, may also be affected. Sometimes the rash has blisters and larger dry, red patches. The rash is accompanied by burning or itching that can last for several days.

The condition is most common in women between the ages of 20 and 40, but it can also affect men and children.
Polymorphic light eruption can affect people with all skin types, but it is most common with fair skin.

A GP may make a referral to a skin specialist (dermatologist) to diagnose the condition. This may involve exposing patches of skin to UV light to see how it reacts. This is called phototesting.

In some cases, a corticosteroid applied to the skin will be recommended to help soothe the rash.

Hydroxychloroquine, a medication used to treat skin conditions, is also sometimes recommended.

There is no cure for polymorphic light eruption, but covering-up, using appropriate sunscreen and avoiding sun exposure can help prevent triggering an outbreak.

Keeping out of the summer sun means your body won't be able to use it to make as much vitamin D, so seek medical advice about vitamin D supplements.