Solar Urticaria (Sun Allergy)
Solar urticaria, also known as sun allergy, is a rare condition characterized by an allergy to sunlight, which leads to the formation of hives on sun-exposed skin. These itchy, reddish spots or welts typically appear within minutes of sun exposure and can persist for a brief period or up to several hours. While the exact cause of solar urticaria remains unknown, it can become a chronic condition, although its symptoms are treatable.
The primary symptoms of sun allergy include itchy, stinging, and burning reddish patches on the skin, which can appear on non-sun-exposed areas. In some cases, hives may blister or crust but don’t leave scars. Solar urticaria can lead to severe allergic reactions like low blood pressure, headache, nausea, wheezing, difficulty breathing, and fainting, sometimes progressing to anaphylaxis. The cause is not fully understood but is believed to involve sunlight-triggered histamine release. Factors like family history, dermatitis, chemical exposure, and certain medications increase the risk. Some react to specific UV light wavelengths, often UVA or visible light.