Contact allergy, viz. allergic contact dermatitis, photo-allergic contact dermatitis and contact urticaria, is a well-studied sub-specialty of dermatology in Singapore. Over the years, numerous studies and anecdotal reports on the subject have been published in both international and local refereed journals. This article reviews the epidemiological data on patch testing and photo-patch testing ...

Patch testing is a well-established method of diagnosing contact allergy wherein patients with a history and clinical picture of contact dermatitis are re-exposed to the suspected allergens under controlled conditions to verify the diagnosis [1]. The results of first innovative patch-testing technique were presented by the German dermatologist, Josef Jadassohn (1863-1936) in 1895. The safety an...