The answer is more complicated than you might think.

By Hayley Sugg
Updated February 02, 2021
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Starting the day with a cup of coffee may be as much a part of your morning ritual as checking your phone for new texts. The jolt of java delivers an eye-opening boost of caffeine. The warm beverage can lull you slowly from your slumber. Plus, coffee is rich in antioxidants and beneficial chemicals.

But for roughly a third of coffee drinkers, that morning cuppa jump-starts more than just their day — it revs up their stomach, too. For these people, going to the bathroom straight after they've finished their first cup is also part of their routine (and for some, purposefully so). Others may even choose to drink coffee for this very reason.

So why does coffee make you need to poop? And is that good or bad? Read on to find out more.

Caffeine

It may seem the most obvious answer for this query, and it is for many people: Caffeine can stimulate your colon, which pushes your digestive system into high gear, especially if you're drinking on an empty stomach.

A cup of coffee has about 95 milligrams of caffeine. A typical cola has about 35 milligrams. So while you may be able to drink a soda without jogging to the loo, coffee's higher hit of caffeine may be enough to stimulate contractions in your colon, which is the signal to your body that you need to poop.

One study found that regular coffee makes the colon 60 percent more active than water. Caffeinated coffee also made the colon 23 percent more active than decaf coffee.

So that means decaf coffee doesn't get off the hook. Indeed, research shows decaf coffee may make you need to poop, too. That means caffeine isn't the only mechanism at play.

Acidity

Like caffeine, coffee's acidity and other chemicals can stimulate the muscles in your intestines. According to the American Chemical Society (ACS), coffee causes your stomach to secrete more gastric acid, a digestive compound that assists in breaking down proteins.

This combination of events may cause your stomach to dump its contents more quickly into the intestines, speeding up the entire digestive system in the process. The, er, end result? Making you have to poop much sooner than you would have without the coffee.

Hormones

Gastrin and cholecystokinin, two hormones that help your body digest food, are responsible for contractions in your colon (to move food along) and increasing bile production (to break food down), says the ACS.

For an as-yet-unknown reason, consuming coffee has been shown to increase levels of these hormones, therefore enhancing their effects in your body and making you have to poop. Research is still unclear what component of coffee increases the release of these hormones.

Dairy

What's causing you to "go" may not be coffee at all if you have a dairy intolerance. According to the U.S. National Library of Medicine, approximately 65 percent of adults have a reduced ability to digest lactose (milk sugar), which can result in symptoms like abdominal pain, bloating, and diarrhea.

So if you have an undiagnosed dairy sensitivity — and creamer and milk are a common addition to your daily coffee — that may be what's causing your rush to the bathroom.

The bottom line: While scientists and researchers know that coffee makes some people feel the urge to poop more acutely than others, they haven't exactly pinpointed what the main cause is — whether it's chemical, hormonal, or a food sensitivity.

Since there are no known negative effects associated with coffee causing you to poop, we suggest you savor your morning cup and just ensure that a bathroom is nearby.

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