What is the cause?

Polymorphic light eruption is thought to be caused by UV light altering a substance in the skin, which the immune system then reacts to, resulting in the skin becoming inflamed.

Polymorphic light eruption can run in families and about a fifth of affected people will have an affected relative.

It's not infectious there's no risk of catching polymorphic light eruption from another person.

Content supplied by the NHS Website

Medically Reviewed by a doctor on 21 Dec 2018