aminolevulinic acid, a photochemotherapeutic agent. It is metabolized to protoporphyrin IX, a photosensitizer, which accumulates in the skin at the sites of application. On exposure of the sites to light of appropriate energy and wavelength together with oxygen, a photodynamic reaction occurs with cytotoxic effects. ▪ INDICATIONS: It is used to treat nonhyperkeratotic actinic keratosis of the face and scalp. ▪ CONTRAINDICATIONS: Known hypersensitivity to porphyrins contraindicates this drug’s use. ▪ ADVERSE EFFECTS: Side effects include crusts, hypopigmentation or hyperpigmentation, ulceration, pain, itching, bleeding, and pustules at the site of application.