Microbiome Modulation in Acne Vulgaris: Comprehensive Narative Review of Oral-Topical Biotics and Future Challenges

Acne vulgaris is a skin disease with a high prevalence, whose pathophysiology involves microbiome dysbiosis, inflammation, and dysregulation of skin barrier function. The long-term use of antibiotics as the primary therapy can raise concerns about resistance, necessitating alternative approaches based on microbiome modulation. Objective: This narrative review aims to synthesize the latest primary evidence on biotic interventions (prebiotics, probiotics, postbiotics, and synbiotics) for acne vulgaris, administered via both oral and topical routes, and to compare the mechanisms of action, benefits, and limitations of each route of administration. Methods: Primary literature search in several databases, such as PubMed, MDPI, SpringerLink, Wiley Online Library, ScienceDirect, and Google Scholar. Priority literature examples are RCTs (randomized controlled trials) or clinical trials published within the last 7 years that discuss the use of biotic interventions for acne vulgaris. Results: Data synthesis indicates that topical biotic interventions containing postbiotics provide faster and more consistent clinical improvement in reducing inflammatory lesions, acne severity scores, and sebum parameters. Conversely, oral biotic interventions show longer-lasting and more variable effects, primarily through modulation of the gut-skin axis and systemic inflammation. Conclusion: Biotic interventions have potential as an alternative or supportive therapeutic approach for acne vulgaris, with oral postbiotics showing the most consistent benefit profile. However, further research with standardized designs and direct comparative testing is needed to strengthen the clinical evidence and its mechanistic action.