Blue light therapy for acne

Blue light phototherapy significantly reduces inflammatory lesions in patients with mild-to-moderate acne, study findings suggest, despite having no effect on Propionibacterium acnes colony counts.
Alternative acne treatments, such as lasers and light therapy, are becoming important due to the emergence of antibiotic-resistant P. acnes, the side-effects of antibiotics, and intolerance or resistance to oral retinoids.
High-intensity, narrow-band blue light therapy is one such promising treatment for acne. It was thought that blue light, by killing or altering the function of P. acnes, could reduce the severity of the condition, especially inflammatory lesions, explain Sadia Ammad (Cardiff University, UK) and colleagues.
However, they say that their finding "raises the possibility that blue light may in fact be improving acne lesions by as yet unknown mechanisms in addition to the accepted mechanism of action by endogenous porphyrin sensitization."
They evaluated the effects of intense blue light within the spectral range of 415-425 nm in the treatment of 21 patients with mild-to-moderate facial acne. All patients received 14-minute treatment sessions twice weekly for 4 weeks.
Acne severity was significantly reduced with blue light phototherapy. Using the Leeds technique, the mean score of acne grading reduced from 1.64 at baseline to 1.35 at week 4.
The mean inflammatory lesion count was also significantly reduced, from 46.71 to 35.33, whereas a trend toward significance was demonstrated for the reduction in noninflammatory lesions, from 23.86 to 19.43.
P. acnes colony counts failed to show a significant reduction at the end of treatment. The mean value for the P. acnes cultures was 4.94 at baseline and 4.80 at week 4.
"The findings demonstrate that inflammatory lesions show the greatest improvement, while evidence exists for reduced colonization in these lesion types by P. acnes in comparison with the highly colonized noninflammatory lesions," Ammad and team comment in the Journal of Cosmetic Dermatology.
They conclude: "Treatment options involving blue light and another topical or systemic agent may prove to be helpful by targeting different factors involved in the pathogenesis of acne."