Individuals who have consumed no alcohol can experience severe intoxication due to a rare medical condition known as Auto-brewery Syndrome (ABS). This phenomenon involves the body’s digestive system producing ethanol internally, leading to symptoms indistinguishable from traditional drunkenness.

Mark Mongiardo, a former high school athletic director, faced significant personal and professional repercussions due to unexplained episodes of intoxication. Beginning in the early 2000s, colleagues and players reported smelling alcohol on him, despite his claim of abstinence. In 2016, he failed a surprise urine test and later, in 2017 and 2019, received two driving while intoxicated (DWI) charges, with breathalyzer readings as high as .18 percent, more than double the legal limit, after consuming only soda. His family became skeptical, suspecting secret drinking, which strained his relationships.

After his second arrest, a family member suggested he consult Dr. Prasanna C. Wickremesinghe, a gastroenterologist specializing in such inexplicable impairments. During supervised testing, after consuming a sugary drink, Mr. Mongiardo’s blood alcohol content steadily rose to .14 percent over eight hours without any alcohol consumption, confirming an ABS diagnosis.

Auto-brewery Syndrome occurs when gut microbes convert carbohydrates and sugars into ethanol at an unusually high rate, overwhelming the liver’s ability to metabolize it. Dr. Bernd Schnabl, co-director of the San Diego Digestive Diseases Research Center, noted that this leads to intoxication similar to drinking alcohol. While instances have been documented since the 1950s, it is considered rare, though recent research suggests it may be more common than previously thought. The American College of Gastroenterology’s annual meeting last October featured multiple presentations on ABS, and studies are growing, including one co-led by Dr. Schnabl involving 22 patients, and an upcoming study by Dr. Wickremesinghe and Dr. Fahad Malik with 34 cases.

Diagnosing ABS is challenging, partly because symptoms can be vague and vary among individuals, often leading to misdiagnosis as mental health conditions like anxiety or depression. Dr. Malik stated that many patients consult numerous specialists before receiving an ABS diagnosis. Doctor skepticism also contributes to under-diagnosis, with some physicians dismissing patients as "closet alcoholics" despite emerging research. Barbara Cordell, a nurse and ABS researcher, recounts her husband Joe Bartnik’s six-year struggle before diagnosis, including an emergency room visit where he registered a .37 percent BAC without consuming alcohol, prompting doctors to assume he was secretly drinking.

Research into the causes of ABS points to an overgrowth of specific gut organisms. Some studies, including Dr. Schnabl’s, identify bacteria such as E. coli and Klebsiella pneumoniae as ethanol producers, while others, like Dr. Wickremesinghe’s, suggest an overgrowth of intestinal fungi. Both Dr. Schnabl and Dr. Wickremesinghe speculate that antibiotic use, which disrupts the gut microbiome, could be a contributing factor, with Dr. Wickremesinghe noting nearly all his study patients had prior antibiotic exposure.

Treatment typically involves dietary changes, particularly reducing carbohydrates and sugars, combined with antifungal or antibiotic medications to rebalance gut flora. Fecal transplants are also being explored in clinical trials for a more permanent solution. Even with successful treatment, patients may experience relapses, alcohol withdrawal symptoms, or even develop new cravings for alcohol, requiring careful management.

For Mr. Mongiardo, dietary changes and antifungal medication brought his ABS under control. He now maintains a carb- and sugar-free diet and abstains from alcohol, carrying a breathalyzer to monitor himself. He has since relocated to Florida and created a TikTok channel to raise awareness, emphasizing the disorder’s reality and its potential impact on undiagnosed individuals.