Polymorphic Light Eruption
This is the commonest cause of sunlight reactions. In its mild form it is often described as ‘prickly heat’ by patients, but it can be more severe and persistent. It causes itchy red bumps, which often join together, to come up usually a few hours after sun exposure. It can affect any area of skin exposed to sunlight, though in m any sufferers some areas of skin get the rash whilst others may be more resistant. It often causes problems only on hot holidays, tending to last for up to a week or so after one returns home. Some patients have the problem in the UK often throughout the Spring and summer, usually from around Easter until September or so. It is common, affecting to some extent around one in six young women , and can start at any age in men or women. The ‘allergic’ skin reaction to the sunlight is to the ultraviolet part of the sunlight. There are two types of ultraviolet in sunlight , A (UVA) and B (UVB). In most patients, the rash is triggered by UVA so, for many people, the only sunscreens that work are 4 or 5 star UVA protective sunscreens (the SPF (sun protection factor) only tells you about protection against UVB). In severe cases, treatments include oral steroids and ultraviolet desensitisation therapy: the choice of treatment depends on the exact features of the rash in an individual.