Updated July 20, 2009
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. Some have a medical condition which makes them more sensitive to sunlight; others are using various medications or topical agents that cause a reaction on the skin when exposed to sun.
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 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.
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
Other forms of reactions to the sun are not caused by allergies. Some of these, such as polymorphous light eruption
, are usually mild and not serious conditions. 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.
Dice, JP. Physical Urticaria. Immunol Allergy Clin N Am. 2004;24:225-246.
DISCLAIMER: The information contained in this site is for educational purposes only, and should not be used as a substitute for personal care by a licensed physician. Please see your physician for diagnosis and treatment of any concerning symptoms or medical condition.