inflammatory reaction from ultraviolet radiation characterized by transient redness, tenderness and occasional blistering

A sunburn is a kind of burn that happens when skin is exposed to sunlight for too long. The ultraviolet part of sunlight breaks down natural chemicals in the skin. This makes the skin become red. Sunburns stay for days or weeks.

Woman showing sunburn on her neck and shoulders.

People with lighter skin sunburn more quickly than people with darker skin. This is because of a dark pigment called melanin that protects the skin. There is more of it in dark-skinned people than in light-skinned people. Eventually, if exposed to too much sunlight, skin cancer may develop. In any event, sunburn can be extremely painful.