Acne phototherapy with a high-intensity, enhanced, narrow-band, blue light source: an open study and in vitro investigation.

The purpose of this study was to investigate the efficacy of phototherapy with a newly-developed high-intensity, enhanced, narrow-band, blue light source in patients with mild to moderate acne. An open study was performed in acne patients who were treated twice a week up to 5 weeks. Acne lesions were reduced by 64%. Two patients experienced dryness. No patient discontinued treatment due to adverse effects. In vitro investigation revealed that irradiation from this light source reduced the number of Propionibacterium acnes (P. acnes), but not Staphylococcus epidermidis that were isolated from the acne patients. Phototherapy using this blue light source was effective and well tolerated in acne patients and had an ability to decrease numbers of P. acnes in vitro, suggesting that this phototherapy may be a new modality for the treatment of acne.