What is a photosensitivity reaction?
A photosensitivity reaction is a disorder in which your immune system overreacts to sunlight. This reaction is sometimes also called a sun allergy.
Photosensitivity causes red, itchy patches on your skin, usually skin that has been in sunlight
Certain medicines or chemicals can make your skin sensitive to the sun
Photosensitivity reactions can run in families
Some diseases can cause a severe photosensitivity reaction
Photosensitivity reactions go away on their own, but medicine sometimes helps you feel better
What causes photosensitivity reactions?
There are different types of photosensitivity reactions that have different causes, including:
Those caused by certain medicines you take
Those caused by certain chemicals you were exposed to
Those caused by diseases you have (such as lupus)
At least 100 medicines and chemicals are known to cause photosensitivity.
Sometimes there doesn't seem to be a particular cause, although photosensitivity sometimes runs in families.
What are the symptoms of a photosensitivity reaction?
Symptoms are different depending on the type of photosensitivity reaction you have. You may have:
Itchy, red bumps
Painful, red patches like sunburn
Symptoms usually appear only on skin that was exposed to the sun. But one kind of photosensitivity reaction can spread to skin that wasn't exposed to sun.
How do doctors tell if I have a photosensitivity reaction?
Doctors suspect a photosensitivity reaction when you have a rash mostly on areas of your skin exposed to the sun. Doctors will ask you about medicines and substances you take or apply to your skin.
Doctors may do tests, such as:
Skin patch tests to see what substances you may be allergic to
Shining a UV (ultraviolet) light on your skin to see if it causes the reaction
How do doctors treat photosensitivity reactions?
Your treatment depends on which type of photosensitivity reaction you have.
Doctors will:
Tell you to stop using any medicines or substances that cause photosensitivity
Give you corticosteroids to apply to your skin or take by mouth
Give you other medicines if the reactions are frequent or severe
Doctors may also have you:
Avoid spending too much time in sunlight
Wear protective clothing when you go outside
