Rethinking Acne Vulgaris: The Gut–Skin Axis as a Central Mechanism and Therapeutic Target

Acne vulgaris is a chronic inflammatory disease of the pilosabaceous unit with a multifactorial pathogenesis involving sebaceous gland activity, follicular hyperkeratinization, microbial dysbiosis, and immune dysregulation. Increasing attention has been given to the role of the skin and gut microbiome, as well as the gut–skin axis, although their clinical significance has not yet been fully explained. This review critically evaluates the current evidence regarding the use of probiotics, prebiotics, and synbiotics in the treatment of acne. Available studies suggest that microbiome-targeted interventions may influence inflammatory pathways, microbial composition, and metabolic regulators such as IGF-1 and mTORC1. Some clinical trials indicate improvements in acne severity and skin parameters following oral or local interventions. However, the evidence is heterogeneous and limited by small sample sizes, short study durations, and variability in formulations and outcomes. Therefore, although microbiome-based strategies may have potential as adjunctive therapy, their clinical efficacy remains uncertain. Further, well-designed, large-scale studies are needed to determine their role in dermatological practice.