Photoallergic Contact Dermatitis: No Fun in the Sun.

Photoallergic contact dermatitis (PACD) is a form of allergic contact dermatitis that occurs due to the interaction between a topically applied chemical and exposure to UV radiation. It can be difficult to identify and requires photopatch testing (PPT) for definitive diagnosis. In this article, we provide an overview of PACD, including clinical features, the most common photoallergens, and why cases may go undiagnosed.