Gut-Skin Axis in Rosacea Highlights Emerging Role of Microbiome-Targeted Therapies

The pathogenesis of rosacea may extend beyond the skin, with growing evidence supporting a gut–skin connection involving small intestinal bacterial overgrowth (SIBO), microbiome disruption, and immune dysregulation, according to Ted Lain, MD, during his session, “Understanding and Harnessing the Gut-Skin Connection in Rosacea.” The session explored diagnostic strategies and emerging treatment concepts targeting this axis.

SIBO was defined as an “unexpected microbial concentration (10^5 colony-forming units/mL) in the jejunal aspirate culture,” associated with factors such as reduced gastric acid, impaired intestinal motility, and immune dysfunction. The condition may contribute to systemic inflammation through disruption of the intestinal barrier.

Dr Lain outlined a proposed mechanism linking gut dysfunction to cutaneous disease. “Leaky gut (impaired intestinal barrier) allows gut bacteria and metabolites to enter the bloodstream and metastasize to skin,” contributing to both barrier dysfunction and immune activation. This process may lead to “cutaneous dysbiosis and barrier impairment” and ultimately inflammatory skin disease, including rosacea.

Diagnostic evaluation for SIBO commonly relies on breath testing, including lactulose or glucose hydrogen breath tests. While widely used, these tests have modest accuracy, with reported sensitivity of 42% for lactulose and 54.5% for glucose-based testing.

Treatment strategies targeting the gut microbiome were also discussed. Rifaximin, a poorly absorbed antibiotic, remains a commonly used option due to its localized gastrointestinal activity. Its mechanism involves inhibition of bacterial RNA synthesis, reducing microbial burden without significant systemic exposure.

Emerging approaches include microbiome modulation through probiotics and fecal microbiota transplantation. The presentation highlighted recent US Food and Drug Administration approval of oral fecal transplant capsules for recurrent Clostridioides difficile infection, raising the question of broader applications. Firmicute-based therapies may increase production of butyrate, a short-chain fatty acid that reduces inflammatory signaling.

The role of probiotics was also emphasized, particularly their ability to alter microbial balance. Increasing the firmicutes-to-bacteroidetes ratio may contribute to reduced inflammation and improved barrier function.

Reference

Lain T. Understanding and harnessing the gut-skin connection in rosacea. Presented at: Music City SCALE Symposium; May 13–17, 2026; Nashville, TN.