The truth about green beer and its potential nasty side effect

Green beer is a fixture at St. Patrick’s Day parties, right alongside “Kiss Me, I’m Irish” t-shirts and guys in cartoonishly large leprechaun hats.

But unlike t-shirts and oversized headgear, there’s a small chance that emerald-hued ales could devastate a delicate stomach.

Dr. Partha Nandi, a board-certified gastroenterologist and a fellow of the American College of Physicians, tells Fox News that consuming green dye, while generally harmless, has the potential to send St. Paddy’s Day revelers straight to the bathroom if ingested in larger quantities.

“If you're just drinking green beer and snacks one day of the year, a few drops of the dye should not make any difference to your health,” Nandi tells Fox News. “[But] you may experience some GI distress with diarrhea.”

The problem, as Nandi points out, is that artificial dyes are not meant to be consumed in anything other than “moderate” amounts.


In a 2012 article published in The Huffington Post, Dr. Braden Kuo, a gastroenterologist who works at the Digestive Healthcare Center of Massachusetts General Hospital, further explained that artificial dyes aren’t easily absorbed into the body. And, upon reaching the large intestine, they have the potential to draw water into the bowels.

Additionally, food colorings may actually dye the stools of those who ingest them, although colorful stools are not necessarily an indicator of a larger health problem. Who could forget Burger King's Halloween-themed burger from 2015?

And just this month, a pink poop pandemic swept the internet after Oreo fans noticed peculiar-hued stools caused by ingesting Peeps-flavored Oreos. But according to Dr. Jamile Wakim-Fleming, a gastroenterologist at the Cleveland Clinic who spoke with, those occurrences were likely the result of undigested dye.

“In the case of Oreo Peeps, it's a food dye called FD&C Red Number 3,” said Wakim-Fleming.

Another possible side effect of green beer is green teeth, but it usually only affects teeth with moderate plaque build-up.

“Green beer can act like the colorful disclosing plaque rinses used to teach kids where they’re missing brushing,” explained dentist Joseph Roberts in Philadelphia magazine. So you might want to avoid swapping spit with people sporting green mouths.

“The green food coloring that is added to the beer stains the bacterial cell walls in plaque. So if his smile is looking all green, it’s probably not just the beer.”


There are always natural dye alternatives, too, but unless a foodstuff lists its ingredients on the label — and a glass of green beer at a pub likely does not — it can be hard to determine the makeup of the food colorings used.

One New York bartender, who wished to remain unnamed, told Fox News that he knows exactly which kind of dye his bar utilizes, because he mixes each beer with green coloring to order. Meanwhile, a representative for a different New York-area bar revealed that they outsource the process, and don’t know exactly how it’s dyed.

But if the origin of the dye is that great a concern, Dr. Nandi might be able to put your fears to rest.

“If you eat minimal to moderate amounts, you should have no real health effects,” explains Nandi.

Nandi is actually more concerned with bar patrons keeping their beer consumption to appropriate levels — after all, there’s only a small chance that green beer will cause diarrhea, but a much larger chance that too many pints can lead to a much worse condition.


“You can develop liver disease, heart disease, certain forms of cancer, and pancreatitis,” warns Nandi, who recommends no more than a single drink per day for women, and two per day for men. “Excessive drinking can also lead to problems at home, at work, with friends, and even with strangers,” he adds.

That said, Nandi isn’t totally against enjoying an alcoholic drink on St. Paddy’s Day — be it green-tinted or otherwise.

“This Friday, have a green beer with friends,” says Nandi. “But don't drink excessively.”