This is a much less common condition and may be induced by longer wavelength (ultraviolet A) and visible radiation as well as ultraviolet B. It is characterised by rapidly developing irritation and in the exposed skin is followed by urticarial wheals. It can occur as part of a photoallergic reaction, in which case avoidance of the relevant allergen will prevent the condition.
Treatment is with antihistamines and sunscreens. In some cases phototherapy with ultraviolet B, narrow waveband or psoralen with ultraviolet A (PUVA), is helpful.
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