Modulation of the microbiome: a paradigm shift in the treatment of acne.

The roles played by the gut-skin axis and the human microbiome have increasingly been explored in various studies. This has led to increased interest in the potential of microbiome-modulatory agents as treatments for various diseases. Probiotics have been explored as both a monotherapy for acne and as an adjunct to reduce the side-effects associated with traditional, established medications to improve patient adherence. We review the evidence to support the use of topical and oral probiotics, prebiotics and synbiotics in treating acne vulgaris. There is some evidence of a correlation between increased Cutibacterium acnes colonization and acne severity, supporting the use of treatments targeting the skin microbiome. However, most studies have relied on in vitro or animal models, or they have involved small sample sizes. Thus, there are limited robust clinical trial data currently available. Furthermore, researchers have tended to overlook the interplay between endogenous and exogenous factors affecting the skin microbiota. While many microbiome-modulatory products are available, their multiple ingredients require further scrutiny to isolate any beneficial components and determine whether they have any potential adverse effects. Additionally, the role that other microbial species play in acne pathogenesis requires further examination.