Sun allergy is a term often used to describe a number of conditions in which an itchy red rash occurs on skin that's been exposed to sunlight. The most common form of sun allergy is polymorphic light eruption, also known as sun poisoning.
Some people have a hereditary type of sun allergy, while others develop signs and symptoms only when triggered by another factor — such as certain types of medications or skin exposure to plants such as limes or wild parsnip.
Mild cases of sun allergy may resolve without treatment. More severe cases may require steroid creams or pills. People who have a severe sun allergy may need to take preventative measures and wear sun-protective clothing.
The appearance of skin affected by sun allergy can vary widely, depending on the disorder that's causing the problem. Signs and symptoms may include:
Itching or pain
Tiny bumps that may merge into raised patches
Scaling, crusting or bleeding
Blisters or hives
Signs and symptoms usually occur only on skin that has been exposed to the sun and typically develop within minutes to hours after sun exposure.
When to see a doctor
See a doctor if you have unusual, bothersome skin reactions after exposure to sunlight. For severe or persistent symptoms, you may need to see a doctor who specializes in diagnosing and treating skin disorders (dermatologist).
Certain medications, chemicals and medical conditions can make the skin more sensitive to the sun. It isn't clear why some people have a sun allergy and others don't. Inherited traits may play a role.
Risk factors for having an allergic reaction to sunlight depend on your particular condition. These include:
Race. Anyone can have a sun allergy, but certain sun allergies are most common in people of certain racial backgrounds. For example, the most common type of sun allergy (polymorphic light eruption) occurs mostly in Caucasians. A less common but more severe variety of sun allergy is most common in Native Americans.
Exposure to certain substances. Some skin allergy symptoms are triggered when your skin is exposed to a certain substance and then to sunlight. Some common substances responsible for this type of reaction include fragrances, disinfectants and even certain chemicals used in sunscreens.
Taking certain medications. A number of medications can make the skin sunburn more quickly — including tetracycline antibiotics, sulfa-based drugs and pain relievers such as ketoprofen.
Having another skin condition. Having atopic dermatitis or another type of dermatitis increases your risk of having a sun allergy.
Having relatives with a sun allergy. You're more likely to have a sun allergy if you have a sibling or parent with a sun allergy.
Preparing for your appointment
You're likely to start by seeing your family doctor or a general practitioner. However, when you call to set up an appointment, you may be referred to a doctor who specializes in skin conditions (dermatologist).
At the time you make the appointment, be sure to ask if there's anything you need to do in advance. For example, if you're going to have tests that check for a reaction to ultraviolet light (phototesting), your doctor may ask you to stop taking certain medications beforehand.