Why Does Coffee Make You Poop? A Gastroenterologist Weighs In

Have you ever finished a cup of your favorite Starbucks coffee only to find yourself on the toilet just a few minutes later? Well, you're not alone. "Why does coffee make you poop?" has a search volume of over 22,000 a month — meaning there are plenty of other people dealing with post-coffee poops.

Pascale M. White, MD, an assistant professor in Mount Sinai's division of gastroenterology and director of the gastroenterology clinic also told POPSUGAR in an interview that coffee can absolutely make you poop — though more research still needs to be done to learn more.

Experts do have some theories, though. We spoke to Dr. White about why coffee makes you poop and what you may want to consider when it comes to your daily caffeine fix.

Does Coffee Make You Poop?

It can for some people, according to Dr. White. In fact, research shows that coffee promotes the urge to poop in at least one-third of the population. Medical professionals aren't quite sure what in coffee makes people have to poop, but studies have laid out a few potential reasons.

Why Does Coffee Make You Poop?

There are some studies that claim coffee "increases what we call the motor activity of the colon, specifically in the last portion called the rectosigmoid," says Dr. White. She cited one study conducted back in 1990 and published in the journal Gut (the main study that people cite when they talk about this subject, she noted) where researchers gave people black, unsweetened coffee, some decaffeinated and some caffeinated, as well as hot water. Four minutes after drinking coffee, eight subjects who, before the study, said it gives them the need to defecate showed increased motor response of the colon that lasted at least 30 minutes. (Note: Of those surveyed who said they felt the urge to poop after drinking coffee, a majority were women. This, according to the study, might be linked to the fact that irritable bowel syndrome, or IBS, affects about twice as many women as men.)

The small study also stated that "the response is not induced by the temperature or volume of the fluid since hot water had no effect on rectosigmoid motility, but is probably caused by a component of coffee other than caffeine." In terms of how specifically coffee itself can increase motor activity or induce a "gastrocolic response," this study and others, like one from 1986, say that it can promote the release of digestion-regulating hormones such as gastrin. Coffee in general, too, can make poop loose because of increased peristalsis, the contraction and relaxation of intestinal muscles, which leaves less time for the colon to reabsorb water from fecal matter and form solid stool, according to One Medical.

How your digestive system responds to coffee can also be connected to what you put in your coffee, namely milk or artificial sweeteners, Dr. White told POPSUGAR. In terms of dairy, some people may be lactose intolerant, meaning they don't have enough of the enzyme lactase to break down lactose sufficiently, which could lead to "GI-related issues, mainly diarrhea," Dr. White explained. You can develop a lactose intolerance later in life, she noted, and some people may have lactose-intolerant reactions toward specific dairy products more than others. "Some people can have this particular reaction with ice cream, but not with yogurt," she said. "So, it's not just all dairy products." But, milk in your coffee can also be the culprit of increased bowel movements and, not to mention, loose stool.

Does Decaf Coffee Make You Poop?

The studies mentioned suggest caffeinated and decaffeinated coffee have a similar effect on the colon, though there is evidence that shows caffeine is a stimulant. One small study from 1998, for example, said that caffeinated coffee had a 23-percent stronger stimulative effect compared to decaffeinated coffee on the colon. Dr. White noted that more research needs to be done for further insight.

The Bottom Line:

Yes, coffee can make you poop — and for a variety of reasons, from increased gut motility to certain dairy products. But it's not usually a sign of concern. If you're worried about how much you're pooping from coffee or what's causing it (like a lactose intolerance), chat with your healthcare provider so they can address your specific symptoms and find a solution that works best for you.