Caffeine makes you poop because it stimulates the muscles of the colon and increases gut movement.
Why
Caffeine stimulates the colon’s muscles and the release of gastrin, which increases motility. Coffee also triggers the gastrocolic reflex.
How common
About 30% of people report a laxative effect from coffee.
It’s not just caffeine
Decaf can have a similar effect, from compounds in the coffee itself.
Tips
Cut down or drink after eating.
See a doctor
If you have ongoing diarrhea.
The gastrocolic reflex
Eating or drinking stimulates the colon to contract through the gastrocolic reflex. Coffee triggers this reflex even more strongly than water. A study found coffee stimulated colon motility as strongly as a meal, about 60% more than water.
Caffeine and decaf
Decaffeinated coffee also stimulates the colon, though a bit less, so other compounds in coffee are involved. These include chlorogenic acids and other substances that raise gastrin, cholecystokinin and acid secretion.
Prevalence
Surveys and small studies suggest that about 30% of people feel an urge to defecate within minutes of drinking coffee, and women report this more often than men.
Other ingredients
Milk, sugar and artificial sweeteners such as sorbitol can add a laxative effect. Lactose intolerance can worsen the effect.
Quantity
Caffeine in amounts of over 200 to 400 milligrams has a stronger effect on the gut. One cup of coffee has about 95 milligrams.
Who is more sensitive
People with irritable bowel syndrome may experience cramping, diarrhea or urgency after coffee.
Tips
- Reduce coffee amount or switch to a smaller cup.
- Drink coffee with food.
- Try cold brew, which is lower in acid for some people.
- Avoid added sweeteners that may stimulate the gut.
- Keep a diary to see how coffee affects you.
Benefits and downsides
This effect can help with regularity for some people with constipation. Too much can cause diarrhea and dehydration.
See a doctor if
You have blood in stool, persistent diarrhea, severe abdominal pain, weight loss or a change in bowel habits lasting more than 2 weeks.
Colon response to coffee
Coffee stimulates the colon. A study published in 1990 in Gut found that coffee caused colonic motor activity comparable to a 1,000 calorie meal, with a response about 60 percent stronger than that of water and 23 percent stronger than decaf. The effect starts within minutes in many people, and surveys suggest about 3 in 10 people feel an urge to defecate after coffee. Caffeine plays a part, but decaf also has an effect, indicating that other compounds such as chlorogenic acids and the release of gastrin contribute.
Who is affected
People with irritable bowel syndrome or sensitive guts are more affected. Cream, sugar substitutes such as sorbitol and large volumes may add to the effect. Reduce the dose, switch to a smaller cup, try cold brew or take coffee with food if it causes urgency. Do not rely on coffee as a laxative. Persistent changes in bowel habits, blood in stool, weight loss or nighttime diarrhea need a doctor’s evaluation.
Based on data from the journal Gut and the Mayo Clinic
