Medications comprising psoralens, chemical compounds found in certain plants and also present in certain perfumes. Once absorbed by the skin, psoralens interact with ultraviolet light, leading to skin tanning or inflammation. These psoralen medications, when combined with ultraviolet light (referred to as PUVA therapy), are employed for treating conditions like psoriasis and vitiligo.
Excessive exposure to ultraviolet light during therapy or an excessive dosage of a psoralen medication can result in skin redness and the formation of blisters. Psoralens present in perfumes can trigger photosensitivity.