[Photoallergy].

Photoallergy is an entity of allergy in the dermatological field. Sunlight is involved in the pathophysiology of photoallergy. Photoallergy is classified into intrinsic and extrinsic diseases. As extrinsic diseases, photosensitivity due to drugs and photocontact dermatitis are important for physicians as well as dermatologists. Physicians should have accurate understanding of these disorders.