Learn more about the causes, symptoms and treatment of this itchy rash that is an allergic reaction to sunlight.
Sun allergy is a broad term. It describes several conditions that cause an itchy rash to form on the skin after being in sunlight or other sources of ultraviolet (UV) radiation. Polymorphous light eruption is the most common form of sun allergy.
Some people have a hereditary type of sun allergy. Others develop symptoms only when triggered by another factor — such as taking medication or touching certain plants. Other types of sun-related reactions occur for reasons that are unclear.
Mild sun allergy may clear up without treatment. Severe rashes may be treated with steroid creams or pills. If you have severe sun allergy, you may need to take preventive steps. For example, wear clothing that shields you from the sun.
How skin with sun allergy looks varies widely depending on the color of your skin and what's causing the symptoms. Signs and symptoms may include:
Symptoms usually occur only on skin that has been exposed to the sun or other source of UV light. Symptoms show up within minutes to hours after sun exposure.
See a health care provider if you have unusual, bothersome skin reactions after being in the sun. For severe or persistent symptoms, you may need to see someone who specializes in diagnosing and treating skin disorders (dermatologist).
Polymorphous light eruption is a rash that affects parts of the body that are exposed to more sunlight as daylight hours get longer, such as the front of the neck and chest. Polymorphous means that the rash can have many forms, such as tiny bumps, raised areas or blisters.
Causes of sun allergy include immune system reactions to sunlight, certain medications and chemicals that 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 include:
If you have a sun allergy or an increased sensitivity to the sun, you can help prevent a reaction by taking these steps:
Apply sunscreen. Use a water-resistant, broad-spectrum sunscreen with an SPF of at least 30, even on cloudy days. Apply sunscreen generously, and reapply every two hours — or more often if you're swimming or perspiring.
If you're using a product that contains physical blockers (titanium dioxide, zinc oxide), apply it over any other products you're wearing — except insect repellent. Insect repellent goes on last. Physical blockers provide the most effective protection for sensitive skin.
The Food and Drug Administration (FDA) requires all sunscreen to retain its original strength for at least three years. Check sunscreen labels for directions on storing and expiration dates. Throw away sunscreen if it's expired or more than 3 years old.
Your health care provider may diagnose sun allergy by looking at your skin. You might need tests, such as:
Treatment for sun allergy depends on the type you have and your symptoms. For mild symptoms, you may need to simply avoid the sun for a few days.
Creams containing corticosteroids are available in both nonprescription and prescription strengths. For a severe reaction, your health care provider may have you take prescription corticosteroid pills, such as prednisone, for a short time.
The malaria medication hydroxychloroquine (Plaquenil) may ease the symptoms of some types of sun allergies.
If you have a severe sun allergy, your health care provider may suggest gradually getting your skin used to sunlight each year as the daylight hours get longer. In phototherapy, a special lamp is used to shine ultraviolet light on areas of the body that are often exposed to the sun. It's generally done a few times a week over several weeks.
These steps may help relieve sun allergy symptoms:
You're likely to start by seeing your primary care provider. Or 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 you need to do anything in advance. For example, if you're going to have tests that check for a reaction to ultraviolet light (phototesting), you might need to stop taking certain medications beforehand.
Before your appointment, you may want to list answers to the following questions:
Your health care provider is likely to ask you a number of questions. Examples may include: