Slurred speech, vomiting, loss of balance – these might be symptoms you associate with being drunk. But for some people with a rare condition, these can occur without drinking any alcohol at all.

The condition is called auto-brewery syndrome, and it’s so rare that only 50 people in the US are thought to have it. It’s only been identified for about a decade, and it's also known as gut fermentation syndrome.

The condition involves a build-up of yeast in the intestines. This gets to a point where ingesting sugar can suddenly trigger a reaction that converts the yeast into ethanol, causing a spike in the body’s blood alcohol content.

"Auto-brewery syndrome has significant effects on life," the National Center for Biotechnology Information notes. "The patient may experience side effects of belching, chronic fatigue syndrome, dizziness, dry mouth, disorientation, hangovers, and irritable bowel syndrome."

Diets high in carbohydrates are found to trigger it most acutely, with some types of yeast being worse than others, such as Candida. There have been some suggestions that a large amount of enzymes in the liver can also cause a problem, although that hasn’t been confirmed.

Essentially, auto-brewery syndrome can make a person feel drunk just from eating. This can sometimes happen almost immediately after eating high-carb food, or it can happen over a couple of days. While experiences vary, some people with the condition report this is usually accompanied by a terrible hangover.

Japanese researchers in the 1970s were the first to look into the condition, but it wasn’t until about a decade ago that the disease was properly identified. Now many case stories about people with the condition have emerged, often being accused of actually being drunk.

In 2016, for example, a woman in New York escaped drunk-driving charges after she successfully argued that she suffered from auto-brewery syndrome. A doctor found that she had high levels of yeast in her intestines that may have caused her alcohol levels to spike.

She had been spotted weaving her car all over the road, with bloodshot eyes and slurred speech. She failed several sobriety tests, including a breathalyzer. Her blood alcohol content was 0.33 percent, which is more than four times the legal limit.

Despite saying she had the condition, getting out of the charge wasn’t easy. Auto-brewery syndrome is not widely recognized, and it can be difficult for it to be taken seriously.

"At first glance, it seems like a get-out-of-jail-free card," Jonathan Turley, a law professor at George Washington University, told the Associated Press. "But it's not that easy. Courts tend to be sceptical of such claims. You have to be able to document the syndrome through recognized testing."

Numerous other people have come forward with accounts of their own struggles with auto-brewery syndrome. Speaking to Vice in 2014, one sufferer called Matthew Hogg said he was initially diagnosed with irritable bowel syndrome as a child. It wasn’t until his later life that his symptoms were recognized as being caused by auto-brewery syndrome.

“[B]y my late teens I was experiencing severe alcoholic hangovers that would usually be at their worst the morning after eating a high carbohydrate meal,” he said. “It was as if I'd been out the previous night and drunk the bar dry, but I hadn't consumed any alcohol.”

Hogg had a particularly tough time with the condition, unable to find work after dropping out of university. He set up The Environmental Illness Resource to try and help others with similarly unknown conditions, and has modified his diet to try and lessen the effects.

That’s not to say everyone agrees about the assessment. Speaking to BBC Future in 2015, forensic toxicologist Wayne Jones said there wasn’t enough evidence to suggest people could produce such large amounts of alcohol in their blood from yeast alone, apart from some exceptional cases.

“Several people over the years have claimed that the alcohol measured in their blood wasn’t caused by drinking beer, whisky or wine but by the body itself,” he said. “I would like to see much more detailed information before I accept the findings as a proven fact.”

But the cases aren’t going anywhere. Another man earlier this year reported feeling drunk after a dinner, despite having nothing to drink. His condition worsened to the point that he had a seizure and had to be taken to intensive care.

Auto-brewery syndrome is something that continues to cause huge complications for a very small group of people around the world. The idea of getting drunk from eating might sound like fun, but for those that suffer from it, that appears to be anything but the case.