Why Does Coffee Make You Poop? What the Research Shows

Part of our Mushroom Coffee guide library.

For many people, the morning coffee and the morning bathroom trip go together. Here is what research says about why coffee makes you poop, why decaf can do it too, why it affects some people and not others, and what to do if it is more than you want.

What you'll learn

• How quickly and how strongly coffee affects the colon
• Why it is not just the caffeine, and whether decaf makes you poop
• Why coffee affects some people more than others
• What to try if coffee upsets your stomach, and when to see a provider

Does coffee make you poop?

For a sizable minority of people, yes. In a survey of 99 healthy young adults, 29% said coffee gave them the urge to have a bowel movement (Brown et al., 1990). When researchers then measured muscle activity in the lower colon, coffee increased it within about 4 minutes in the people who reported the effect, and the response lasted at least 30 minutes. A drink of hot water did nothing (Brown et al., 1990).

Why does coffee make you poop?

Researchers have not pinned down a single cause, but several factors seem to be involved:

• Caffeine. Caffeinated coffee stimulated the colon 23% more than decaf in one study, so caffeine contributes (Rao et al., 1998).
• Other coffee compounds. Decaf also stimulates the colon, so caffeine cannot be the whole story (Brown et al., 1990; Nehlig, 2022).
• Gut hormones. Both regular and decaf coffee stimulate the release of cholecystokinin, a digestive hormone, and coffee may also act through hormones such as gastrin and motilin (Nehlig, 2022).
• Stomach acid. Coffee stimulates stomach acid secretion, although it does not seem to speed up how fast the stomach empties (Nehlig, 2022).
• Timing. A meal also stimulates the colon (Rao et al., 1998), so coffee with breakfast may combine both effects.

Note that one of the reviews cited here was commissioned by a coffee-industry science institute, although the author states it had no role in preparing the manuscript (Nehlig, 2022).

Does decaf coffee make you poop?

It can. In the study that measured colon activity within minutes, both regular and decaf coffee increased it in people who said coffee made them go (Brown et al., 1990). Caffeinated coffee had a somewhat stronger effect than decaf in another study (Rao et al., 1998). Decaf still contains a little caffeine, typically 2 to 15 mg in an 8-ounce cup (FDA), but the response to decaf is more likely due to coffee's other compounds.

Why does coffee affect some people and not others?

Most people in the survey did not report the effect, and in the lab study, the colon responded only in those who said coffee made them go (Brown et al., 1990). What you add and how much you drink can matter too:

• Milk and cream. If you are lactose intolerant, milk can cause bloating, gas and diarrhea, usually within a few hours (NIDDK).
• Strength and size. A larger or stronger cup means more caffeine; see how much caffeine is in a cup of coffee.

Can coffee cause diarrhea or constipation?

A normal cup is more likely to speed things up than slow them down. According to a 2022 review, coffee drinking is not linked to chronic constipation and, if anything, is linked to less of it (Nehlig, 2022). For some people, though, coffee can loosen stools or upset the stomach, especially in large amounts. Caffeine increases stomach acid, which can cause an upset stomach or heartburn (MedlinePlus).

What to try if coffee upsets your gut

• Have it with food rather than on an empty stomach.
• Drink less or switch to a smaller cup, or try half-caf.
• Change the milk to lactose-free or a plant milk if lattes are the problem (NIDDK).
• Try a lower-caffeine drink such as green tea, matcha or a mushroom coffee blend. Our guides cover whether matcha makes you poop and whether mushroom coffee makes you poop.
• Ask your provider about caffeine if you have GERD or ulcers (MedlinePlus).

When to see a health care provider

See a provider if you have diarrhea for more than 2 days, signs of dehydration, severe pain in your abdomen or rectum, a fever of 102 degrees or higher, or stools that contain blood or pus or are black and tarry (MedlinePlus). These are not normal reactions to a cup of coffee.

Common myths (quick reality check)

• Myth: Coffee makes you poop only because of the caffeine. Reality: Decaf also stimulates the colon, so other compounds in coffee and the gut hormones it releases play a part.

• Myth: Everyone poops after coffee. Reality: In one survey, 29% of healthy young adults said coffee made them need to go. Many people notice no effect.

• Myth: Coffee causes constipation because it dehydrates you. Reality: Coffee drinking is not linked to chronic constipation; if anything, it is linked to less of it.

Frequently asked questions (FAQ)

Why does coffee make you poop?

Coffee stimulates the muscles of the colon, partly through caffeine and partly through other compounds and gut hormones such as cholecystokinin. In one study, caffeinated coffee stimulated the colon about as much as a 1,000-calorie meal.

Does coffee make everyone poop?

No. In a survey of 99 healthy young adults, 29% said coffee gave them the urge to go. In lab tests, the colon responded only in people who reported the effect.

How fast does coffee make you poop?

For people who respond, colon activity can rise within about 4 minutes of drinking coffee and last at least 30 minutes.

Does decaf coffee make you poop?

It can. Decaf also increased colon activity in people who said coffee made them go, although caffeinated coffee had a somewhat stronger effect in another study.

Is it normal to poop after drinking coffee?

Yes, for many people. It is a common response to coffee, especially in the morning or with breakfast. See a provider if you have ongoing diarrhea, pain or blood in your stool.

Can coffee cause diarrhea?

It can loosen stools in some people, especially in large amounts or with milk if you are lactose intolerant. Try a smaller cup, having it with food, or a different milk.

Does coffee help with constipation?

Coffee drinking is not linked to chronic constipation and may be linked to less of it, and it stimulates the colon in many people. It is not a treatment, so talk to a provider about ongoing constipation.

Related guides

• Does mushroom coffee make you poop?
• Does matcha make you poop?
• How much caffeine is in a cup of coffee?
• Mushroom coffee vs regular coffee
• Can turmeric cause diarrhea or constipation?

Disclaimer and when to seek help

This article is for general education and is not medical advice. These statements have not been evaluated by the Food and Drug Administration. Our products are not intended to diagnose, treat, cure, or prevent any disease. Talk to your health care provider if you have ongoing digestive symptoms, GERD or ulcers, are pregnant or breastfeeding, or take medication.

References

1. Brown SR, Cann PA, Read NW. "Effect of coffee on distal colon function." Gut, 1990;31(4):450-453. doi:10.1136/gut.31.4.450
2. Rao SS, et al. "Is coffee a colonic stimulant?" European Journal of Gastroenterology & Hepatology, 1998;10(2):113-118. doi:10.1097/00042737-199802000-00003
3. Nehlig A. "Effects of Coffee on the Gastro-Intestinal Tract: A Narrative Review and Literature Update." Nutrients, 2022;14(2):399. doi:10.3390/nu14020399
4. MedlinePlus (U.S. National Library of Medicine). "Caffeine".
5. MedlinePlus (U.S. National Library of Medicine). "Diarrhea".
6. National Institute of Diabetes and Digestive and Kidney Diseases. "Symptoms & Causes of Lactose Intolerance".
7. U.S. Food and Drug Administration. "Spilling the Beans: How Much Caffeine Is Too Much?" Content current as of August 28, 2024.