Inclusion Criteria:

• Male or female aged 18 years or older.
• Have sufficient cognitive capacity to give written informed consent.
• Have an eruption on photo-exposed sites, which is to be further classified using one (or more) of the categories below:
• Known photosensitivity disease
• History of sunscreen reaction
• Sun exposed site dermatitis during summer months
• Any sun exposed site dermatitis problem

Exclusion Criteria:

• Male or female aged 17 years or younger
• Have had potent topical steroid applied to the photopatch test site on the back in the previous 5 days. (This potentially suppresses reactions which would otherwise have been visible)
• Have skin disease on the back which is too active to allow testing. (This obscures the sites of testing by making differentiation between a positive result and other skin disease difficult)
• Be prescribed systemic immunosuppressant medication (e.g. prednisolone, methotrexate, azathioprine, ciclosporin) (This potentially suppresses reactions which would otherwise have been visible)
• Be taking any photoactive medicine (for example thiazides, sulphonamide derivatives, amiodarone, fluoroquinolones, chlorpromazine, NSAIDs, quinine). (This is a relative exclusion. Many centres may wish to go ahead despite such medication).