Drunk Without Alcohol: Strange Condition Ferments Food in Gut Auto-brewery syndrome made these men appear to be drunk without ever drinking.

 -- Nick Hess lives an active lifestyle, biking, swimming and playing volleyball. But three years ago, the 34-year-old waiter practically collapsed onto the floor with intense stomach pain.

“[I] thought maybe I had a stomach bug or something. It was terrible,” Hess told ABC News’ “20/20.”

This Man Appears Drunk, But Hasn't Been Drinking

Mystery Stomach Bug Sickens 202, Shuts Down Washington Lake

Jennifer Lawrence Hopes Mystery Illness Is ‘All in My Mind’

But then there was something else strange happening to Hess.

“We would be watching television … and by the end of the evening, he would start to be confused, and he would start slurring,” Hess' wife Karen Daw told “20/20.” “And he did smell like he had alcohol on his breath.”

Hess said he was not a frequent drinker.

Daw, who works in an office, began filming videos on her phone of Hess appearing to be intoxicated even though he hadn’t been drinking, with the intent of showing doctors the footage. Daw and Hess met with several doctors to try to find out what was happening to Hess.

“The amount of tests I could never tell you. I've lost count a long time ago,” Hess recalled. “I've had at least three colonoscopies, three endoscopes.”

But some doctors -- and even Daw -- were suspicious that Hess was a closet alcoholic.

“I went through the entire house looking for alcohol,” Daw said. “Anywhere that I think that maybe you could hide a small bottle or a small flask. The painful part was just doubting him.”

In 2011, Hess was arrested for operating a vehicle under the influence after he called the police when he said he was hit by an oncoming car.

While Hess told police he drank only one beer 12 hours earlier that day, police asked the slurring and wobbly Hess to take a breathalyzer test.

According to the police report, Hess was nearly three times over the legal limit.

"It just made me more determined to try and figure out what was going on with him," said Daw of the incident.

Matthew Hogg, 34, from Middlesbourough, England, also went through similar experiences. Hogg spent his youth suffering from chronic stomach pain. His family spent over $60,000 in treatments.

“My teen years were spent visiting various doctors and clinics and therapists, psychological therapists, and, like, alternative therapists,” Hogg told “20/20.” “I felt at university things were starting to get really out of control. During these episodes, I'd get so drunk, that I was completely wasted after only a few drinks.”

For Hogg and Hess, the lack of answers was taking a toll on their lives.

“There were times where I actually considered taking my own life,” said Hogg.

“It was crushing me. I never left the couch,” Hess said.

Finally, after years of not knowing what was wrong with her husband, Daw came across an article on auto-brewery syndrome. “It was, like, ‘Oh my gosh, this is what he has. I'm convinced of it,’” said Daw.

Auto-Brewery syndrome causes the stomach to use excess yeast in the intestine to ferment carbohydrates and other sugary foods into alcohol.

After being tested for yeast, Hess’ results revealed that he had four times the normal amount of yeast. Hess’ doctor Anup Kanodia had Hess completely change his diet to eliminate foods that break down to sugar, such as breads, pasta and rice. After just four weeks, Hess’ mysterious symptoms vanished.

“I'm the luckiest person alive. I keep getting better and better, and I love it,” Hess said.

Though some might be skeptical, Kanodia said the evidence is clear that auto-brewery syndrome is a real illness.

“Patients don’t want to wait 20 years ‘til I publish all the research. They want help today,” Kanodia told “20/20.” It’s not clear how many people suffer from auto-brewery syndrome, but Kanodia is determined to get the word out in order to spare others years of misery.

Hogg also made his own drastic dietary changes in order to relieve his symptoms after he too was diagnosed with auto-brewery syndrome, but his symptoms didn’t completely go away. “They were reduced quite a bit, but they didn't go away completely,” said Hogg.

As he continues to try and find the best cure for himself, Hogg is hopeful.

“I’m not sure a 100 percent cure is possible after all these years, but I'd like to think maybe I'd get to 75 percent and have a job, get married, maybe have kids, live a normal … life,” Hogg said.

“I’m a very stubborn person, so I’ll never give up.”