Effects of repetitive photodynamic therapy using indocyanine green for acne vulgaris

Background: Indocyanine green (ICG) is a photosensitizer recently introduced for the treatment of acne. Objective: To evaluate the efficacy and safety of photodynamic therapy (PDT) using ICG in subjects with acne vulgaris and to evaluate whether there was a difference in the efficacy of ICG-PDT between different numbers of treatment. Materials and methods: Subjects with acne on the face were included. ICG lotion (0.1%) was applied for 30 minutes, and a long pulse diode laser was used. Three or five treatments per subject were performed over 2 weeks. Acne lesion counts and Leeds revised acne grades were evaluated at baseline and 2 weeks after the last treatment. Results: In total, 47 subjects completed the study. After both three and five ICG-PDT sessions, a significant reduction in acne lesions and significant improvement in Leeds revised acne grades were found in all treated subjects compared to baseline. In the subjects receiving five ICG-PDT sessions, the reduction of papules/pustules was greater than in the subjects receiving three ICG-PDT sessions (P < 0.01, respectively). However, there was no significant change in the count of nodules/cysts, although it is a negative trend (P = 0.066). Adverse effects were minimal. Conclusion: ICG-PDT using long-pulsed diode laser can be a safe and effective tool for acne vulgaris. Moreover, repetitive treatments of five can cause further improvement of inflammatory acne lesions.