A split-face clinical trial of conventional red-light photodynamic therapy versus daylight photodynamic therapy for acne vulgaris

Background Photodynamic therapy (PDT) is considered an effective treatment for acne vulgaris. A significant drawback is pain during illumination. Daylight PDT (DL-PDT) is more tolerable. Objective To assess and compare the efficacy and tolerability of DL-PDT and C-PDT for acne vulgaris through a prospective split-face trial. Methods and Materials Fifteen patients underwent 4 treatment sessions at 3-week intervals. First, 5-aminolevulinic acid (ALA) was applied to the entire face, after which the face was divided into 2 symmetrical areas: The right side was exposed to sunlight, and the left half was illuminated with red light. Photographs were obtained and evaluated by two dermatologists blinded to the study protocol. The patients reported side effects and downtime. Results There was a statistically significant decrease in the number and percent change of inflammatory and non-inflammatory lesions on both sides. Adverse effects were markedly decreased on the DL-PDT side compared to the C-PDT side (p < .01). The average downtime duration was longer for the C-PDT side (p < .001). Conclusion DL-PDT was at least as effective as C-PDT with fewer adverse effects and a shorter downtime duration.