Polymorphic light eruption is a common reaction to sunlight (ultraviolet light) that occurs in light-sensitive individuals.
The cause is unknown. Some experts think it is a type of delayed allergic reaction.
Small red pimples and blisters appear on the skin within 1 - 4 days after exposure to sunlight. The lesions may also appear as scaly skin.
Use sunscreen. Sun protection with broad spectrum sunblock that works against UVA rays is important.
Certain immunosuppressive pills may be used for more severe cases. Some people benefit from phototherapy in which the skin gets sensitized to the sun.
Polymorphous light eruption