Photodynamic therapy with aminolevulinic acid topical solution and visible blue light in the treatment of multiple actinic keratoses of the face and scalp: investigator-blinded, phase 3, multicenter trials.

Objective: To determine the safety and efficacy of photodynamic therapy (PDT) using 20% wt/vol aminolevulinic acid hydrochloride (hereinafter "ALA") and visible blue light for the treatment of multiple actinic keratoses of the face and scalp.

Design: Randomized, placebo-controlled, uneven parallel-group study.

Interventions: Patients (N = 243) were randomized to receive vehicle or ALA followed within 14 to 18 hours by PDT.