Facial erythema as a result of benzophenone allergy.

Benzophenones are common causes of photoallergy and are increasingly used in products other than traditional sunscreens. Patients may be unaware of any sunscreen exposure when using a product such as shampoo containing benzophenone. Benzophenones also may produce photoallergic contact urticaria, in addition to delayed contact and photocontact dermatitis, which may complicate the clinical presentation. Allergy to benzophenone should be considered in the diagnosis of patients with patchy erythema of the face and neck that is not typically eczematous and that may otherwise be attributed to a rosacea diathesis, lupus erythematosis, or simple flushing. Patch and photopatch testing are indicated to evaluate these patients for allergy to benzophenone.