why does coffee give me diarrhea?

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For many, the rich aroma of a brewing pot of coffee in the morning is akin to a warm welcome into the day. The caffeine jolt that follows seems almost magical in its ability to transform zombie-like beings into semi-functional humans. But, for some, especially among the ranks of coffee devotees, this mystical elixir can also lead to an unwelcome, and undeniably urgent, digestive response — diarrhea. It’s a puzzle that has plagued many a morning enthusiast and health advocate: why does coffee, beloved yet incendiary, have such a gut-wrenching reputation?

The Science Behind Coffee and Digestion

The seemingly simple act of drinking coffee can initiate a complex chain reaction in the human body, particularly in the highly intricate system that is our digestive tract.

Coffee’s Components that Kickstart a Rumble in Your Tummy

Coffee, when brewed as the standard drip, espresso, or French press, consists of a cocktail of compounds beyond its headline act of caffeine. These include acidic substances like chlorogenic acids and N-alkanoyl-5-hydroxytryptamides (C5HTs), which stimulate stomach acid production and can increase the production of certain hormones in the intestines.

Your Digestive System on Coffee

This increased gastric acid secretion effectively revs up the entire digestive process. For those with sensitive stomachs, a sudden spike in acid can be overstimulating and may lead to discomfort, bloating, as well as a hastening of bowel motility. This means that the food you ate alongside your cup of joe can zoom through your system quicker than you can say “refill, please,” leading to the looser stool characteristic of diarrhea.

Does Coffee Give You Diarrhea?

There is evidence that caffeine-containing drinks such as coffee can act as a laxative. Problems usually start when we drink more than 3 cups a day, so if you normally have 1 cup of coffee in the morning to start your day, you probably have nothing to worry about. The caffeine in coffee does seem to stimulate the digestive system. It acts as a pro-motility agent, which means that it can cause the muscles in your stomach to contract and push food and liquids through your digestive system more rapidly. If your stomach can’t process the coffee quickly enough, that leads to diarrhea for anyone with existing sensitivities.

It Might Be Lactose Intolerance

If you get diarrhea after drinking coffee every time you sip on your favorite cup of java, there may be something else going on. In the US alone, there are almost 50 million people that can be classified as lactose intolerant and 65 percent of the global population has some level of trouble digesting anything containing lactose. It may not be the coffee or the caffeine that’s causing your diarrhea. The problem may actually be the cream or milk you’re using in your coffee. Switching to black coffee or at least reducing the amount of cream you use may solve your diarrhea.

Coffee and the Digestive Process

As we’ve mentioned, coffee has been identified as a pro-motility agent that can speed up the digestive system. This isn’t a bad thing for most coffee drinkers as it just makes them more regular. However, as the coffee enters your digestive system, it causes the number of contractions in your intestine to speed up. There’s general agreement that there’s something in coffee causing it to act as a pro-motility agent, but there isn’t agreement on whether that something is caffeine. Some scientists believe it could be something else in the coffee that causes the reaction. Changing to a decaffeinated brand of coffee may help, but when you do that, you also lose the stimulating effect of the coffee.

Acidity in Coffee Can Lead to Diarrhea

Another potential cause of diarrhea for coffee drinkers is the acidity of the beverage. That acidity can speed up the production of bile causing it to build up in the stomach. All of that extra bile can upset your stomach and it can cause diarrhea as your system becomes unsettled.

Coffee’s Impact on Gut Health

Coffee’s relationship with digestive health isn’t all bad, though. The beverage can have beneficial effects as well, particularly on the microbiome—the ecosystem of bacteria living in our gut. Research suggests that the polyphenols found in coffee can act as anti-inflammatory and antioxidant agents, potentially protecting the gastrointestinal tract. However, these positive effects can be overshadowed in individuals with preexisting sensitivities or imbalances in their gut flora.

Stock photo showing close-up, elevated view of a cappuccino coffee served for breakfast on a cafe table. The cappuccino has a typically frothy milk foam surface with a heart shape pattern latte art design.

When the Good Goes Bad for Some

For those with lactose intolerance, coffee can be a double-edged sword. Often mixed with milk, the dairy component can cause digestive upset. Additionally, some studies suggest that certain compounds in coffee, when combined with high-fat dairy, can lead to acute increases in hormone secretion, further stimulating the intestines and potentially triggering diarrhea.

Individual Factors: Who’s at Risk?

Not all coffee consumers are equally likely to run to the restroom post-sip. Some are more prone to this response than others.

High Caffeine Sensitivity

Individuals with heightened caffeine sensitivity may experience the laxative effect more readily. For some, a single cup can be enough to induce bowel contractions and the subsequent rush to empty the bowels.

Underlying Digestive Conditions

Preexisting conditions such as irritable bowel syndrome (IBS), Crohn’s disease, or ulcerative colitis can amplify the impact of coffee on the digestive system. The combination of these conditions, the caffeine, and the acidity in coffee can create a gastrointestinal trifecta that spells trouble for sufferers.

Ways to Enjoy Coffee Without Upsetting Your Stomach

Coffee aficionados need not abandon their beloved brew just because it seems that their system can’t quite handle it. There are strategies to employ that could minimize the risk of an upset stomach.

Choose Your Beans Wisely

Opting for coffee with lower acidity levels, such as dark roasts, can be gentler on the digestive system. Cold brew, a method known for producing a less acidic product, might also be a more stomach-friendly alternative.

Timing Is Everything

Consuming coffee on an empty stomach can aggravate known sensitivities. Having a small meal or snack before—or alongside—your coffee can help buffer the effects.

Adapt Your Brew

Preparing coffee using cold water extraction reduces the release of acidic compounds and certain irritants, potentially leading to a less aggressive reaction in the gut.

How to Drink Coffee and Avoid Diarrhea

So what can we do to avoid the onset of diarrhea after drinking coffee? We’ve already suggested switching to a decaffeinated brew as a potential solution, but that’s not ideal for most coffee drinkers who enjoy the stimulating qualities of their brew in the morning. A better solution may be to switch to a richer coffee with less acidity, such as espresso. You may also want to cut back on the sugar or sweeteners as these can irritate the stomach. Additionally, remember to have something to eat with your coffee. This will help to settle your stomach and dilute the acidity of the coffee, providing a buffer against the potential digestive upset.

When to Seek Professional Advice

While the occasional jolt leading to a hasty trip to the bathroom might be benign, persistent diarrhea can indicate more serious health issues. It’s important to know when to seek professional advice.

Red Flags and Consultation

Look out for persistent or chronic diarrhea, especially if it’s accompanied by other concerning symptoms such as blood in the stool, unexplained weight loss, fever, or severe abdominal pain. If any of these apply, it’s time to put down the coffee mug and pick up the phone to make an appointment with a healthcare provider.


The relationship between coffee and the digestive system is a nuanced and multifaceted one. For some, it’s as simple as being more cautious about how and when they consume their beloved beverage. For others, it can be a sign of underlying health issues that need attention. By understanding the potential causes of coffee-induced diarrhea and taking proactive steps, it’s possible for coffee lovers to continue enjoying their daily cup while respecting the delicate dance of their digestive ecosystem. One thing is for certain: whether you’re a die-hard coffee fan or simply curious about the complexities of your biology, unraveling the intricacies of this morning ritual can lead to a more balanced and pleasant experience with each and every pour.