The inducing or exacerbating effect of sunlight on skin diseases is often not appreciated in tropical countries, perhaps because of the perennial presence of sunlight, and a retrospective review of photodermatoses seen in a referral skin clinic was therefore carried out. The photodermatoses seen were secondary photoaggravation of primary skin diseases (32.2%), systemic drug photosensitivity (11.3%), polymorphic light eruption (13%), chronic actinic dermatitis (5.3%), solar urticaria (5.3%), actinic prurigo (4%), photoallergic contact dermatitis (2.6%), porphyria (1.3%) and xeroderma pigmentosum (1.3%). Compared with the results of Western studies, there were more photoaggravated underlying skin diseases and systemic drug photosensitivity, and fewer idiopathic photodermatoses and photoallergic contact dermatitis; the common photoallergens were chlorpromazine, promethazine and musk ambrette, very similar to those seen in the West.

Our data suggest that solar urticaria is an uncommon photodermatosis and a rare form of urticaria. Wheals were mostly elicited by visible light and/or UVA. A combination of antihistamines and sunscreens provided a useful form of therapy for patients with solar urticaria.