Dermatologists turning to the literature for guidance on the effectiveness of light therapies on acne vulgaris might come up empty-handed. The body of research looking at lasers and other light therapies for acne fails to offer robust evidence on efficacy and more, according to a systematic review published in October in the British Journal of Dermatology.

But a few notable clinical takeaways did surface.

Pooled data from three studies, reflecting a total 360 subjects with moderate-to-severe acne, showed that photodynamic therapy with red light-activated methyl aminolevulinate had a similar effect on changes in lesion counts as a placebo with red light. On this topic, the authors judged the quality of evidence as moderate, and they mentioned that current evidence doesn’t support methyl aminolevulinate photodynamic therapy as a standard moderate-to-severe acne treatment.