A man charged by police for drink driving actually had a bizarre medical condition that caused his stomach to brew beer.

The unidentified 46-year-old was pulled over in 2014 and a breathalyser showed he was five times over the drink-drive limit.

He maintained he hadn't consumed anything alcoholic, but neither the police nor his family believed him.

The man was eventually diagnosed with auto-brewery syndrome (ABS) in 2017, after seeing a specialist at Richmond University Medical Center in New York.

A 46-year-old man in the US is one of only five people in the world to have been diagnosed with auto-brewery syndrome (file)

He was found to have high levels of a fungus called Saccharomyces cerevisiae in his faeces.

The fungus is also known as brewer's yeast because it's used by beer-makers to convert carbohydrates in grains into alcohol.

Further tests showed this conversion process was taking place inside the patient's gut.

Every time he consumed carbohydrate-packed foods his blood alcohol level shot up, sometimes to as high as 400 milligrams per 100 millilitres – 11 times the drink-drive limit.

It is thought that the condition was triggered by a course of antibiotics that he was prescribed in 2011 for a thumb injury.

He told medics he had experienced mental fogginess, dizziness and memory loss since the injury.

The symptoms, which were repeatedly misdiagnosed as depression, forced him to give up his job. It is unclear what his job was.

WHAT IS AUTO-BREWERY SYNDROME? Auto-brewery syndrome (ABS) causes sufferers to feel intoxicated and unable to perform simple tasks. It usually occurs due to yeast accumulating in the intestines after the sufferer ingests sugar. The syndrome occurs when a sufferers' yeast in their intestines grow out of control, possibly following a course of antibiotics. ABS may also be caused by abnormal enzymes in the liver. Anyone of any age can suffer. ABS is so rare its prevalence is unknown. There is no cure. Avoiding sugar and carbohydrates may help to control symptoms, as well as frequently monitoring a sufferer's blood alcohol content. Source: Gundry MD Advertisement

Dr Fahad Malik, a gastroenterologist at Richmond University who treated the man, believes the drugs disrupted the patient's balance of gut microbes.

This, he said, most likely caused the rapid growth of the fungus S. cerevisiae, which is normally present in low levels in the gut.

Auto-brewery syndrome has been reported as a side effect in some people with gut disorders such as Crohn's disease.

But this is thought to be the first case of the rare condition as a result of antibiotic use.

The condition is so rare that there have only been five cases in the last 30 years.

The patient was given probiotics, anti-fungal medication and was put on a strict low-carbohydrate diet to flush out the excess fungus in his gut.

He has now been symptom-free for almost two years. His case will be presented at the annual meeting of the American College of Gastroenterology later this month

Dr Malik told New Scientist: 'He was extremely happy when he started to recover, because for years, no one believed him.

'The police, doctors, nurses and even his family told him he wasn't telling the truth, that he must be a closet-drinker.

'Now he is off antidepressants, he's back at work and he's finally getting on with his life.'