Why Coffee Causes Bowel Movements, Explained by a G.I. Doctor and Science

Understanding the Link Between Coffee and Bowel Movements

For many people, the morning ritual of drinking coffee is as routine as brushing their teeth. But for some, it also comes with a predictable trip to the bathroom. This phenomenon has sparked curiosity about how coffee affects the digestive system and why it can trigger an urge to poop so quickly.

Dr. Josephine Ni, a gastroenterologist at the University of Texas Southwestern and an expert in inflammatory bowel diseases, explains that while caffeine plays a role, the coffee bean itself is responsible for this effect. “Caffeine doesn’t just wake up your brain—it boosts gut activity too,” she says. It stimulates the colon, leading to bowel contractions that help move stool along. Additionally, caffeine lowers the sensory threshold for the desire to defecate, making the body more sensitive to signals from the gut.

Interestingly, a 2022 study published in Nutrients found that even decaf coffee had similar effects on bowel movements in rats. This suggests that other compounds in coffee, beyond caffeine, may be involved in triggering this response.

The Science Behind Coffee’s Effect on the Gut

According to Dr. Ni, coffee raises levels of gastrin, a hormone that triggers the “gastrocolic reflex.” This reflex sends a signal to the gut when the stomach is full, prompting the urge to poop. Coffee amplifies this effect, making the body more responsive to the need to eliminate waste.

In addition to gastrin, coffee also increases the production of cholecystokinin (CCK), a chemical messenger that tells the pancreas to release digestive enzymes and causes the gallbladder to contract. These actions are part of the digestive process that ultimately leads to a bowel movement.

Kris Sollid, RD, a registered dietitian and senior director of research and consumer insights at the International Food and Information Council, adds that coffee’s acidity may play a role. When coffee raises gastrin levels, the body produces more gastric acid to kickstart digestion. Coffee also contains chlorogenic acid, a plant-based antioxidant that lowers the pH of the stomach and speeds up the movement of food through the digestive tract.

Can You Prevent the Urge to Poop?

While pooping after coffee is common, it’s not just a habit. “Coffee’s pro-motility effects have been measured against placebo,” Dr. Ni explains. The need to go after coffee comes from how it moves the digestive system, not just from routine.

Some people may develop a tolerance to coffee’s laxative effects over time, but this is likely due to increased tolerance to caffeine rather than other compounds in coffee. That means switching to decaf might not necessarily reduce the bowel-stimulating effects. “Both caffeinated and decaffeinated coffee have been shown to stimulate gastrin and CCK release,” Dr. Ni says.

Is This a Healthy Response?

In most cases, coffee’s effect on the gastrointestinal system is a normal and healthy response. Research suggests that moderate coffee consumption is linked to better gut health and a range of benefits. A 2025 study published in the European Heart Journal found that moderate coffee consumption is associated with a lower risk of type 2 diabetes, heart disease, and all-cause death—especially when consumed in the morning.

However, some individuals are more sensitive to coffee and its effects. People with conditions like irritable bowel syndrome (IBS) or inflammatory bowel disease (IBD) may find that coffee triggers their symptoms. More research is needed to fully understand these differences in sensitivity.

What Makes Your Coffee Too Stimulating?

Certain additives can make coffee more stimulating. For example, coffee syrups often contain sugar alcohols, which act as osmotic laxatives. Also, adding dairy to coffee can cause gastrointestinal issues for those who are lactose intolerant.

If you’re sensitive to coffee’s laxative effects, try drinking it black to see if you’re reacting to something you add to your cup. Alternatively, consider alternatives like tea or a caffeinated soda for your daily pick-me-up.

When to Seek Help

If you experience uncomfortable bowel movements after coffee, it may be worth discussing with your doctor. This could indicate an underlying health issue, such as a gastrointestinal disorder. Consulting with a healthcare professional can help identify the cause and determine the best course of action.

For more information on wellness and health, explore resources that provide expert insights into daily health practices and digestive well-being.