Patch testing can confirm and identify the cause of allergic contact dermatitis. The TRUE Test is a simple method of patch testing that, despite its limitations, can be useful in the general practice setting.
Patch testing is the main method used to ascertain if a patient has allergic contact dermatitis, and, if so, the causative allergen(s). Allergic contact dermatitis is a common form of exogenous dermatitis – see the box for an overview of types and prevalence of dermatitis. Patch testing should not be confused with prick or scratch testing for type I allergy, which is used mainly for investigating atopic diseases and urticaria.