All you need to know about: auto-brewery syndrome

A small number of people in the world experience a strange condition in which they feel drunk, and exhibit signs and effects of drunkenness (like slurred speech and tipsyness), despite not having consumed any or very minimal amounts of alcohol.

This medical condition, known as auto-brewery syndrome (ABS) or gut fermentation syndrome, is rather rare, and occurs when bacteria or fungi in the gut produce high levels of ethanol, especially after a carbohydrate-heavy meal, causing symptoms of intoxication.

Instances of this condition were first reported in Japan in the 1950s, but it continues to be underdiagnosed. Apart from the physical effects, like stomach ache, nausea, vomiting, hangovers, and even alcohol poisoning when levels are too high, this syndrome can get in the way of normal life and also lead to serious legal and social consequences.

Here’s all you need to know about auto-brewery syndrome:

Why does ABS occur?

Our gut contains a wide variety of microbes, including some that produce alcohol, such as Saccharomyces cerevisiae, also known as brewer’s yeast. Usually, after consuming carbohydrate-rich food, these microbes produce a minuscule amount of ethanol, which, under ideal circumstances, is metabolised before it reaches the bloodstream.

However, in people with auto-brewery syndrome, these microbes – whether fungi or bacteria – produce ethanol at high rates, making it difficult for the body to clear it properly and efficiently.

Research suggests that the condition occurs due to an imbalance in gut microbes that results in the overgrowth of certain species, thereby causing rapid internal fermentation of carbohydrate-heavy meals.

Studies have also found that this condition is more commonly reported in people with comorbidities such as diabetes, liver disease, Crohn’s disease, and gastrointestinal disorders. Frequent or long-term use of antibiotics is also seen as a contributing factor.

Besides the gastrointestinal tract, some people, though highly rarely, may experience ABS in the oral cavity or the urinary system.

What are the effects of ABS?

Living with ABS can be challenging. Short-term symptoms include nausea, vomiting, poor coordination, disorientation, irritable bowel syndrome, and chronic fatigue syndrome. Those with the condition may also experience severe hangovers.

The condition can also have long-term health impacts. Anxiety, depression, mood changes, and other mental health issues may develop over time.

High levels of alcohol production in the body may also prevent individuals from driving, as they can test above legal limits; not to mention the risk of injuries from falls caused by disorientation.

The symptoms may appear quite spontaneously and randomly, too. Going about normal life may, therefore, be difficult, with social relationships also being affected.

How to address ABS?

A doctor may diagnose a person with ABS after a series of tests, including a physical exam, blood tests, and a breathalyzer test. To assess the body’s response to carbohydrates, the medical practitioner may also perform an oral glucose tolerance test. A hydrogen breath test and a stool test are some other diagnostic measures.

For treatment, correcting the imbalance of gut microbes is the first step. Lifestyle changes are key in this regard. Antibiotics or antifungals may be recommended, along with dietary modifications: increasing protein intake, reducing carbohydrates, and adding probiotic foods. Foods to avoid generally include refined foods, white rice, potatoes, foods with added sugars, and milk, among others.

With the right kind of lifestyle changes and medication, ABS can be managed with minimal chances of a relapse in the future, according to research.

Published – March 22, 2026 08:00 pm IST