Polymorphic light eruption

What is it?

Polymorphic light eruption is a fairly common skin rash triggered by exposure to sunlight or ultraviolet (UV) light.

What are the symptoms?

An itchy or burning rash appears within hours, or up to two to three days after exposure to sunlight. It lasts for up to two weeks, healing without scarring.

The rash usually appears on the parts of the skin exposed to sunlight – typically the head, neck, chest and arms. The face isn’t always affected.

Who’s affected?

It’s more common in women than men. It particularly affects people who are fair, although it can also affect those with dark skin.

What causes it?

It’s thought to be caused by UV light altering a substance in the skin, which the immune system reacts to, resulting in the skin becoming inflamed. It can also run in families.

What’s the treatment?

There’s no cure, but avoiding the sun between 11am and 3pm and wearing protective clothing when outdoors will help. Use a sunscreen that is SPF 30 or above with a good UVA rating.

Your GP can prescribe corticosteroid cream or ointment to apply when the rash appears. You should apply it sparingly and don’t use it if you don’t have a rash.

It’s sometimes possible to increase the resistance of your skin to the sun. This involves visiting a hospital dermatology department three times a week for four to six weeks in the spring. Your skin is gradually exposed to a little more UV light every visit to build up your skin’s tolerance.

You may be able to increase the resistance of your skin at home. This is known as hardening and involves going outside for short periods in the spring sunshine to build up your tolerance.