Levulan photodynamic therapy is a treatment method for certain skin conditions developed by Dusa Pharmaceuticals. The active ingredient is δ-aminolevulinic acid (ALA). Food and Drug Administration (FDA) approval for actinic keratosis was received in December 1999; it is also prescribed against acne but this is an off-label use, which means it is not approved by the FDA.
A 20% solution of ALA is applied to the lesions, and after 14–18 hours wait the skin is irradiated with blue light for 15 minutes. This generates an active form of oxygen in the skin that kills cells and bacteria. The treated areas are sensitive to light, and patients must protect themselves against bright sunshine for two or three days after treatment. Patients must stop using topical acne medicine and avoid steam rooms, hot showers, and generally protect the skin in every way possible for up to one week after treatment.
Clinical trials indicate an 80% success rate for face lesions and a 50% success rate for scalp lesions after a 12 week course of treatment.