Auto-brewery syndrome is a rare medical condition in which gut microbes convert carbohydrates and sugars into ethanol at significantly elevated levels, causing patients to become intoxicated without consuming alcohol. The condition was first reported in scientific literature in the 1950s, with early U.S. examples appearing in medical journals in the ’80s. Interest in the condition is growing: a recent Nature Microbiology study included 22 patients, and a forthcoming study includes 34. A recent American College of Gastroenterology annual meeting in October featured five separate presentations on auto-brewery cases.
Auto-brewery syndrome appears to be caused by multiple factors, including overgrowth of specific gut bacteria such as E. coli and Klebsiella pneumoniae, and intestinal fungi overgrowth. Research indicates that antibiotic exposure may play a role. In one study of nearly three dozen confirmed cases, all but one patient had been exposed to antibiotics, either shortly before symptom onset or several years prior. The condition is difficult to diagnose because symptoms are vague and variable—commonly including mood changes, anxiety, depression, aggression, fatigue, brain fog, and changes in speech and gait. Patients are often initially misdiagnosed with mental health conditions and sometimes dismissed as “closet alcoholics.”
Treatment approaches depend on the underlying cause. For bacterial overgrowth, a combination of antibiotics and probiotics is used to rebalance the microbiota. For fungal overgrowth, antifungal medications are prescribed. Patients whose symptoms are caused by bacterial or fungal overgrowth often benefit from dietary carbohydrate and sugar restriction. Some patients never experience another episode after treatment, while others experience chronic or recurring symptoms. A small clinical trial is currently examining whether fecal transplants could help restore gut microbiota and treat the condition more permanently.
This article is an AI-assisted summary. All facts and figures are drawn from the original report: https://www.boston.com/news/health/2026/04/06/the-mystifying-syndrome-that-makes-people-spontaneously-drunk/