Sun allergy (or photosensitivity) is caused when the sun-exposed skin reacts abnormally to sunlight. It occurs due to reaction of the immune system on exposure to sunlight. The exact cause of why some people develop sensitivity to sunlight is not known. Sun allergy can affect any skin type, but it tends to be more common in fair skinned populations. About 5-20% of fair skinned people are affected by sun allergy. Read to know how long the effects of sun allergy last.
- Duration of symptoms: Most people with sun allergy develop the symptoms after a few hours of exposure. Only rarely do the symptoms start after just a few minutes of exposure in the sun. The symptoms can last from 1 to 7 days. The symptoms usually resolve if further exposure to sunlight is prevented. Some common symptoms include an itchy or burning skin rash as red plaques or small fluid-filled blisters. In some cases, the fluid-filled blisters may rupture and bleed. In severe cases of sun allergy, the itchy or painful rash may be confused with hives and large blisters may form on the skin. Some people may develop symptoms, such as chills, headache or nausea as well. In most people, the symptoms respond well to treatment.
- Extent of symptoms: Symptoms usually begin on areas that are exposed to sun, such as the back of the hands, the outside areas of the arms, lower legs and neck. In cases with severe sun allergy, symptoms may develop not only in exposed areas, but under clothing as well. Most cases of sun allergy start in young adults, but actinic prurigo (an inherited form of sun allergy) begins early in life i.e. during childhood or adolescence. In most cases, rashes due to sun allergy heal without scarring, but some people with severe actinic prurigo may develop pitted scars.
- Effect of climate on sun allergy symptoms: Climate affects the symptoms of sun allergy. Temperate climate is best suited for people with sun allergy as sunlight is not harsh almost throughout the year keeping the skin reacting all year round. Symptoms tend to be worse for people, who live in tropical climate or those, who live at a higher altitude as the sun is much closer and therefore, sunlight is more intense. In tropical climates, the symptoms may last throughout the year.
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