This Is Why Your Morning Coffee Always Makes You Poop, According to a Gastroenterologist

Caffeinated coffee is a natural laxative for some people.
Image Credit: JGI/Jamie Grill/Tetra images/GettyImages

If you suddenly feel the urge to go number two after your morning cup of coffee, your body is responding in a completely natural way.

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Of course, it can be a bit of an inconvenience if you're on-the-go and need to ​go​, but this sudden need is your body's way of reacting to the caffeine and warm fluid in your coffee — and possibly the ingredients you've mixed into it.

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This isn't necessarily an issue in and of itself, but it can be a problem if you're experiencing diarrhea from your coffee. Here's everything you need to know about why coffee makes you poop and what to do if it's causing belly woes.

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Why Does Coffee Make You Poop?

Caffeinated coffee may increase the amount of acid your stomach produces and your colon movements, and it can lead to a laxative effect in some people, per a June 2017 review in the World Journal of Gastroenterology.

The amount of time it takes you to have a bowel movement after drinking coffee depends on your body. When caffeine enters your system, it gets your intestinal muscles moving. This advances the contents of your intestines through your digestive system in a process called peristalsis.

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"Caffeine acts as a hyper-mobility agent, meaning it promotes the movement of the gastrointestinal tract," says Lisa Ganjhu, DO, a gastroenterologist at NYU Langone Health.

Coffee's hot temperature can even aid in bowel movements. "Warm fluid is one of the stimulants that helps with bowel movements," says Dr. Ganjhu. "Some people can increase their bowel movements with just a warm glass of water. For other people, the caffeine really helps things move along as well."

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Warm fluids loosen the contents of your intestines and can also stimulate your entire digestive system, similar to if you started up an engine. As peristalsis continues, you'll eventually feel the urge to have a bowel movement.

It's less clear what the role of caffeine is in individuals who have irritable bowel syndrome (IBS), an intestinal disorder that can cause pain, gas, diarrhea and constipation.

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Several studies have indicated coffee and tea among the foods associated with symptoms in people with IBS, note the researchers of the ​World Journal of Gastroenterology​ review. "On the other hand, habits of coffee drinking have not been noted to be more common among IBS patients than among healthy controls."

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Can Coffee Cause Diarrhea?

Coffee can cause diarrhea for some people, usually because they're drinking too much of it or they're stirring in something that doesn't agree with them.

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If your poop is loose and watery and you have to go more than three times in a day, you have diarrhea. Drinking a cup of coffee probably won't cause you to sprint to the bathroom, but too many cups in one day might give your stomach a gurgling feeling that indicates diarrhea is on its way.

When matter passes through your digestive system so quickly that your colon doesn't have enough time to absorb the liquid from your stool, it can result in diarrhea, says Dr. Ganjhu.

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Caffeine affects everyone differently, but it's best to stick to moderate consumption of caffeinated products such as coffee to avoid bathroom woes like diarrhea. The U.S. Food & Drug Administration (FDA) recommends no more than 400 milligrams per day, which is about four cups of coffee. (Keep in mind that a cup is 8 ounces, which is 4 ounces less than a Tall at Starbucks.)

"If you're drinking a lot of coffee and having a lot of bowel movements, I would say to cut back a bit," Dr. Ganjhu recommends.

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If you need to reduce your caffeine intake, do so gradually. Stopping suddenly can cause symptoms like headaches, anxiety and nervousness, per the FDA.

Also keep in mind that you may be getting caffeine from other sources, such as tea, chocolate, medicine or plants such as guarana.

What you add to your coffee may also spur diarrhea. If you have lactose intolerance, the lactose in milk or creamer can cause diarrhea. Keep in mind that lactose intolerance can occur with age because your levels of the enzyme that helps digest lactose drop after childhood.

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Similarly, many people experience diarrhea as a result of fructose (a sugar found in fruits and honey) or even artificial sweeteners such as sorbitol and mannitol, per the Mayo Clinic.

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Can Coffee Help With Constipation?

In some situations, caffeine can actually relieve or prevent constipation, Dr. Ganjhu says. Remember that constipation refers to having fewer than three bowel movements per week, even though how often a person "goes" varies widely, per the Cleveland Clinic. The longer it takes you to have a bowel movement, the more difficult it can become for stool to pass. You may notice that your stools are dry and hard, or that having a bowel movement is painful or difficult.

In addition to acting as a diuretic, caffeine also triggers the contraction of your colon. Through repeated contractions, your colon regularly moves waste through its five feet of tubing.

If you get your caffeine through coffee, the warm fluid of the coffee may also help soften painfully hardened stool that's characteristic of constipation.

That said, caffeine intake can have side effects, such as anxiety. If you're constipated because of stress, the caffeine might make the situation worse. A healthy approach to treating constipation is to eat more high-fiber foods, such as vegetables and legumes, and include more physical activity in your day, per Cedars-Sinai.

"All of these things are additive and work on different modalities," says Dr. Ganjhu. "Coffee adds stimulation, fluid and a little shift in pH, whereas the fiber adds bulk to the stool, which stimulates more colonic motions."

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Can Caffeine Cause Constipation?

Surprisingly, yes. Caffeine can sometimes help with constipation, but in other cases, coffee can actually cause constipation. The same goes for energy drinks, caffeine pills and other substances with caffeine.

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Here's why: Because caffeine is a diuretic, it can have dehydrating effects, meaning that it makes you pee out a lot of fluid, which then doesn't go to your colon where it would soften your stool. The dry, hardened stools that result from dehydration can cause constipation. Because of their stiffness, your colon struggles to move them along and excrete them from your body. In this manner, caffeine can either cause constipation or worsen existing conditions.

You can typically avoid this side effect by making sure you stay well hydrated. That means drinking at least eight cups of water a day and eating water-rich foods like fruits and veggies.

Changes in Poop to Look Out For

It's not uncommon to have to "go" soon after a cup of coffee, but there are some poop problems that are abnormal that you should talk to a doctor about.

According to Penn Medicine, certain poop colors and characteristics that could spell trouble include:

  • Light-colored poop​: If your poop is yellow, clay-colored or very light brown, it could be a sign of an infection or inflammation in your gallbladder, liver or pancreas. It could also be a result of alcoholic hepatitis or a blockage in the bile ducts.
  • Black poop​: Although this is likely due to certain foods or supplements — like black licorice, blueberries or iron supplements — it can also be a sign of bleeding or tumors in the digestive tract.
  • Red poop​: A small amount of blood when you wipe could be due to constipation, but it could also be a sign of bleeding in the rectum or anus, abnormal blood vessels, swelling in the lining of your stomach and other issues.
  • Diarrhea​: You should see your doctor if diarrhea lasts more than a few days, even when you cut back on caffeine, because it can be caused by bacteria, viruses, food intolerances, diseases or colon problems.
  • Floating poop:​ If your poop floats, you could be experiencing poor absorption of nutrients, too much gas caused by diet changes, infection or pancreatitis. If you have other symptoms like significant weight loss, talk to your doctor.

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