Does Sun Allergy Exist?

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In my practice, I often encounter people who think they have a sun allergy. With exposure to sunlight, they experience symptoms such as itching, hives, or burning. Some have visible rashes while others don't.

While some people are truly more sensitive to sunlight than others and may have a hereditary type of sun allergy, many people use the term "sun allergy" when, in fact, their reaction to sunlight is caused by use ​of various medications or topical agents that cause a reaction on the skin when exposed to sun.

Signs and symptoms of a reaction to sunlight usually only affect areas exposed to the sun and may include:

  • Blisters or hives
  • Redness, itching, or pain
  • Very small bumps or raised patches of bumps
  • Areas of scaling, crusting, or bleeding

Solar Urticaria

Solar urticaria is a form of chronic hives that is caused by exposure to sunlight. People with this condition experience itching, redness, and hives on areas of skin exposed to sunlight. At times, symptoms can be confused with a sunburn, although solar urticaria can occur within minutes of exposure to the sun and goes away much quicker (less than a day) after sun exposure has stopped.

Cholinergic Urticaria

Cholinergic or heat urticaria is a form of chronic hives that is caused by an increase in body temperature. Hives are caused by any increase in body temperature, such as hot showers, exercise, spicy foods, or being under too many covers in bed at night.

Strong emotions may also cause hives to occur in people with cholinergic urticaria.

Sunscreen Allergy

While contact dermatitis to sunscreens is not as common as allergy to cosmetics, it is not rare. The reaction to sunscreens can occur anywhere the substance is applied on the body, although it tends to be more common on the areas of the body with the most exposure to the sun.

This is called “photo-contact dermatitis.”

Photo-contact dermatitis usually occurs in a sun-exposed pattern on the body. These areas would include the face (but not the eyelids), the “V” area of the upper chest and lower neck, the backs of the hands and the forearms. The area of the neck under the chin is usually not affected.

Other Causes of Rashes With Sun Exposure

Most cases of sun allergy resolve on their own with time and soothing skin balms such as calamine lotion and aloe vera, available over-the-counter at most pharmacies, can help alleviate discomfort. More severe cases may require treatment with ibuprofen or, in more extreme cases, systemic or topical steroids. However, people with a known severe sun allergy should always take precaution to cover up or stay indoors during the times of day when sunlight is strongest. 

Other diseases that cause sensitivity to sunlight, such as porphyria and systemic lupus erythematosus, can be serious medical conditions. Therefore, anyone who experiences rashes as a result of sun exposure should consult their physician.

Source:

Rodriguez E, Valbuena MC, Rey M, Porras de Quintana L. 2006. Causal agents of photoallergic contact dermatitis diagnosed in the national institute of dermatology of Colombia. Photodermatol Photoimmunol Photomed 22(4): 189-192.

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