Solar urticaria is a type of chronic hives called physical urticaria because the hives are caused by a certain stimulus on the body. In this case, the stimulus is exposure to the sun. Hives develop minutes after exposure and resolve in less than 1 hour. Skin that is constantly exposed to UV radiation, like on the face or hands, is usually not affected. Most people with solar urticaria have itching and sometimes a burning sensation, but they usually don't have pain like you would expect with a sunburn.
Diagnosis
Solar urticaria is diagnosed based on the typical appearance of the rash only on sun-exposed areas. At times, the doctor will perform a phototest by exposing the skin to various wavelengths of light to determine the specific wavelength that causes symptoms.Treatment
The following treatments may be helpful depending on the wavelength of light involved:- Antihistamines: Antihistamines taken regularly help control symptoms.
- Sunscreen: Sunscreen helps only if the wavelength of light that causes symptoms is within the range that the sunscreen blocks.
- Avoidance: Avoiding exposure to identified wavelengths, such as wearing protective clothing that blocks the offending wavelengths, also only helps if the clothing and wavelengths match up.
- Photohardening: Photohardening is the practice of developing tolerance with increasing amounts of exposure to increasing measures of light.
Sources:
Amar, SM, and SC Dreskin. ìUrticaria.î Prim Care. 35(2008): 141-57, vii-viii.
Grattan, Clive and Anne Kobza Black. "Urticaria and Angioedema." Dermatology. 2nd. Ed. Jean Bolognia. New York: Mosby, 2008: 261-76.
Habif, Thomas. "Urticaria and Angioedema." Clinical Dermatology, 4th Edition. Ed. Thomas Habif, MD. New York: Mosby, 2004. 129-61.
Zuberbier, Torsten and Marcus Maurer. ìUrticaria: current opinions about etiology, diagnosis and therapy.î Acta Derm Venereologica. 87(2007): 196-205.
