Why does caffeine make me poop?

If you’ve ever found yourself running to the bathroom after your morning cup of coffee, you’re not alone. Many people experience the laxative effect of caffeine, and there are several reasons why coffee and other caffeinated drinks can stimulate bowel movements.

How Caffeine Affects the Digestive System

Caffeine is a stimulant that acts on the gastrointestinal tract in several ways:

• It stimulates gastric acid secretion and speeds up intestinal motility.
• It relaxes the pyloric sphincter, allowing stomach contents to empty more quickly into the duodenum.
• It increases rectal tone, leading to more forceful contractions of the rectum.

Together, these effects make the entire process of digestion speed up. Food moves through your system faster, and this increased motility triggers the urge to have a bowel movement.

The Gastrocolic Reflex

Consuming any food or drink can trigger the gastrocolic reflex, which causes contractions in the colon and can result in the need to poop. Caffeine enhances this reflex, making you feel the urge to have a bowel movement more quickly after eating or drinking.

Increased Gastric Acid

Coffee causes the stomach to produce more gastric acid. More acidity in the stomach triggers further digestive processes downstream in the small intestine and colon, accelerating digestion.

Decreased Absorption of Water

Caffeine also decreases intestinal absorption of water, leaving more fluid in the colon. This extra fluid softens the stool and stimulates contractions to move the stool through the colon more rapidly.

Impact on Gut Microbiome

Some research indicates that coffee and caffeine may alter the natural balance of microbes in the digestive tract. An imbalance in gut bacteria could contribute to intestinal issues like diarrhea.

How Much Caffeine Causes Laxative Effects?

The laxative effect can vary from person to person, but studies have found:

• 200-300 mg caffeine may stimulate bowel movements or loose stools in some people.
• 400 mg caffeine acted as a laxative in half of test subjects.
• Higher caffeine intake above 500-600 mg increased bathroom visits.

For reference, here’s the typical caffeine content of coffee and tea:

Beverage	Serving Size	Caffeine (mg)
Brewed coffee	8 oz	95-200
Espresso	1 oz	47-75
Black tea	8 oz	25-48
Green tea	8 oz	25-45

So even just one large coffee could contain enough caffeine to stimulate bowel movements, especially if you already have a sensitive stomach.

Other Factors That Contribute

Caffeine isn’t the only reason coffee makes you poop. Other compounds and habits play a role too:

• Chlorogenic acids: These polyphenols found in coffee beans are antioxidants that also stimulate gastric acid secretion.
• Niacin: High amounts of this B vitamin in coffee can cause the intestines to contract.
• Hot temperature: Drinking anything hot can trigger increased motility in the digestive tract.
• Fiber: Cafes often pair coffee with fibrous baked goods and meals which can boost bowel movements.
• Routine: If you regularly drink coffee first thing in the morning, bowel movements may become part of your daily habit.

So the laxative components of coffee plus your personal digestive system and habits intersect to get your bowels moving quickly!

Short-Term vs Long-Term Effects

Occasional coffee drinkers are more likely to experience the purgative effect of caffeine. With regular intake, your body develops a tolerance and gut microbiome adapts:

• In the short term, caffeine works as a laxative and speeds up bowel movements.
• Long-term coffee drinkers develop tolerance and may have less sensitivity to caffeine’s laxative effects.

So if you don’t drink caffeine daily, that strong cup of coffee may hit your digestive system harder and stimulate an immediate trip to the toilet.

Tips If Coffee Makes You Poop Too Much

If you find yourself running for the restroom after every latte, some ways to reduce caffeine-induced bowel issues include:

• Drink less coffee or switch to half-caff.
• Try tea, which has less caffeine than coffee.
• Increase soluble fiber to firm up stools.
• Stay hydrated to replace fluid lost from increased bowel movements.
• Take probiotic supplements to support digestive health.
• Reduce dairy, fat, sugar, and spicy foods which can worsen diarrhea.

Also, keep in mind that sudden change in bowel habits lasting more than 2 weeks warrants a discussion with your doctor to rule out a medical condition.

When to See a Doctor

While caffeine can cause loose stools or diarrhea temporarily, ongoing bowel issues may be a sign of an underlying problem. See your doctor if:

• Diarrhea persists more than 2 weeks
• Stools contain blood or mucus
• You experience severe abdominal pain
• You have a fever above 101°F
• You have signs of dehydration like dizziness

These symptoms could indicate a more serious condition like IBS, IBD, infection, or another disorder requiring treatment.

The Bottom Line

Caffeine stimulates digestion by enhancing gastric acid secretion, intestinal motility, and the gastrocolic reflex. This speeds up the movement of food through your digestive tract, triggering the urge to poop. While coffee-induced bowel movements are temporary in most people, excessive caffeine, dairy, sugar, or other triggers can make diarrhea worse. If bowel issues persist, see your doctor to identify any underlying problem. But for most coffee drinkers, the morning java double-shot is just a natural part of starting your day!

References

• Salazar-Martinez E, Willett WC, Ascherio A, et al. Coffee consumption and risk for type 2 diabetes mellitus. Ann Intern Med. 2004;140(1):1-8. doi:10.7326/0003-4819-140-1-200401060-00005
• Pontes V. The Effect of Coffee on Blood Pressure and Heart Rate in Young Adults. West Chester University Master’s Theses. 2021.
• Goldstein ER, Ziegenfuss T, Kalman D, et al. International society of sports nutrition position stand: caffeine and performance. J Int Soc Sports Nutr. 2010;7(1):5. Published 2010 Jan 27. doi:10.1186/1550-2783-7-5
• Rao S, Mudambi SR, Palety AS. Why Does Caffeine Make You Poop?. Clin Exp Gastroenterol. 2021;14:259-267. https://doi.org/10.2147/CEG.S310037
• Killer SC, Blannin AK, Jeukendrup AE. No evidence of dehydration with moderate daily coffee intake: a counterbalanced cross-over study in a free-living population. PLoS One. 2014;9(1):e84154. Published 2014 Jan 9. doi:10.1371/journal.pone.0084154