Some people have an allergic reaction when exposed to sunlight.
Sun allergies are a real medical problem, but fortunately they are rare and the symptoms usually fade within 24 hours. More common than true sun allergies are sun sensitivities that can mimic some of the same symptoms.
Sun Allergies
Some people are allergic to sunlight. When exposed to the sun, these people will develop a red, itchy rash, often on the back of their hands, arms, lower legs and neck.
Exposure Time
In some allergic people, a reaction can be triggered by just a few minutes of exposure to sunlight.
Solar Urticaria
People with a sever sun allergy may develop hives (called Solar urticaria) or even small blisters instead of a rash. For reasons that are unknown, young women are most likely to develop Solar urticaria.
Immune Response
This sun allergy occurs because the immune system sees skin cells that have been affected by sunlight as foreign invaders and attacks them. Sun allergies appear to be inherited.
Photosensitivity
Some people may develop a photosensitivity, which can be caused by certain medications or chemicals, and will develop a rash when exposed to sun, but they do not have a true allergy.
