Topical riboflavin versus 5-aminolevulinic acid photodynamic therapy for the treatment of mild to moderate acne: A split-face randomized study

Background: ALA-PDT has been widely used in mild to moderate acne vulgaris worldwide. However, very few studies used riboflavin-PDT to treat acne vulgaris. Objective: To investigate the efficacy and adverse events of riboflavin-PDT to treat mild to moderate facial acne, and compare it with ALA-PDT on a non-inferiority basis. Methods: 33 eligible patients were enrolled, and 30 patients completed follow-up. Either side of the face was assigned randomly to riboflavin or ALA blue-light-PDT. Patients received 3 sessions of PDT in 1-week intervals and were followed up at weeks 4, 6, and 10. Results: Both ALA and riboflavin-PDT significantly reduced non-inflammatory and inflammatory lesions at weeks 4, 6, and 10 compared to baseline (P all <0.001). For the primary outcome, the difference in the improvement rate of total lesions between the Ribo and ALA side was 2.6 % (-4.3 %, 12.5 %; p = 0.71), which didn't reach the inferiority margin. Patients described greater in-treatment pain and burning sensation (P < 0.001), more prominent post-treatment erythema (P = 0.003), hyperpigmentation (P < 0.001), and desquamation (P = 0.006) on the ALA side than on riboflavin side. Conclusion: The efficacy of riboflavin-PDT was comparable to that of blue-light ALA-PDT in treating mild to moderate acne vulgaris. Riboflavin-PDT had fewer in-treatment and post-treatment adverse events than ALA-PDT.