Sun allergy, also known as photosensitivity or photodermatitis, is a skin reaction to sunlight or artificial ultraviolet (UV) light. The exact cause of sun allergy is not fully understood, but it is believed to be a result of an abnormal immune system response to sunlight.

Symptoms of sun allergy can vary from person to person and can include:

• Redness, itching, or burning of the skin
• Blisters, hives, or rash
• Swelling or inflammation of the skin
• Headache, fever, or nausea
• In severe cases, sun allergy can cause anaphylaxis, a life-threatening allergic reaction that can result in difficulty breathing and loss of consciousness.

To prevent sun allergy, it's important to protect your skin from sun exposure by wearing protective clothing, using sunscreen with a high SPF, and avoiding prolonged exposure to sunlight or artificial UV light. If you experience symptoms of sun allergy, you should seek medical attention. Your doctor may prescribe topical or oral medications to reduce inflammation and alleviate symptoms.

If you are diagnosed with a sun allergy, it's important to take steps to manage the condition and avoid triggers that may cause an allergic reaction. Your doctor may recommend avoiding certain medications, such as antibiotics and diuretics, which can increase sensitivity to sunlight. In severe cases, phototherapy or other medical treatments may be necessary to manage symptoms.

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.

If you have a sun allergy or an increased sensitivity to the sun, you can help prevent a reaction by taking these steps:

• Avoid the sun during peak hours. Try to stay out of the sun between 10 a.m. and 4 p.m.
• Avoid sudden exposure to lots of sunlight. Many people have sun allergy symptoms when they are exposed to more sunlight in the spring or summer. Gradually increase the amount of time you spend outdoors so that your skin cells have time to adapt to sunlight.
• Wear sunglasses and protective clothing. Long-sleeved shirts and wide-brimmed hats can help protect your skin from sun exposure. Avoid fabrics that are thin or have a loose weave — UV rays can pass through them.
• Use sunscreen. Use a broad-spectrum sunscreen with an SPF of at least 30. Apply sunscreen generously, and reapply every two hours — or more often if you're swimming or perspiring.
• Avoid known triggers. If you know that a certain substance causes your skin reaction, such as a medication or contact with wild parsnip or limes, avoid that trigger.

Treatment depends on the type of sun allergy you have. For mild cases, simply avoiding the sun for a few days may be enough to resolve the signs and symptoms.

Medications

Creams containing corticosteroids are available over-the-counter and in stronger prescription forms. For a severe allergic skin reaction, your doctor may prescribe a short course of corticosteroid pills, such as prednisone.

The malaria medication hydroxychloroquine (Plaquenil) may ease the symptoms of some types of sun allergies.

Therapy

If you have a severe sun allergy, your doctor might suggest gradually getting your skin used to sunlight each spring. In phototherapy, a special lamp is used to shine ultraviolet light on areas of your body that are often exposed to the sun. It's generally done a few times a week over several weeks.