Optimizing treatment of acne with photodynamic therapy (PDT) to achieve long-term remission and reduce side effects. A prospective randomized controlled trial.

Photodynamic therapy with methyl aminolevulinate (MAL-PDT) is an effective treatment of acne vulgaris, but is associated with side effects. We performed a prospective randomized split-face study aimed at optimizing MAL-PDT treatment. Patients (n = 33) were randomized to two or four treatments of PDT with MAL on one cheek and placebo vehicle on the other cheek, 1-2 weeks apart. A 1.5-h pre-treatment with the MAL cream was followed by illumination with red light (20 J/cm2). Assessments were performed before treatment and 4, 10, and 20 weeks after the last treatment. In comparison to baseline, the number of inflammatory lesions at 20 weeks on cheeks treated with MAL-PDT showed a relative decrease of 74% in the group with two treatments and 85% in the group with four treatments. This new treatment regimen for both MAL-PDT and red-light-only PDT, with shortened pre-treatment and reduced light dose, could be an effective modality.