While smoking may not directly make you have to poop, it can have a range of impacts on your digestive system.

  • It is unclear whether smoking has a laxative effect or not.
  • Smoking may worsen diarrhea and increase the risk of Crohn’s disease because of its inflammatory effect on the bowel.
  • Smoking may also increase the risk of gastroesophageal reflux disease (GERD), gallbladder disease, and other conditions that affect digestion.
  • Quitting smoking can reduce the risk of a wide range of illnesses.

You may wonder if smoking cigarettes has any effect on your bowels, like coffee does. After all, isn’t nicotine a stimulant, too?

But the research on the intersection between smoking and diarrhea is mixed.

Read on to learn more, as well as the other harmful side effects of cigarettes.

Laxatives are substances that can free up stool that’s stuck or impacted in your large intestine (colon), letting it pass more easily through your colon.

Laxatives may also be used to cause the muscle reactions in your bowel that move stool along, which is called a bowel movement. This type of laxative is known as a stimulant laxative because it “stimulates” a contraction that pushes stool out.

Many people feel nicotine and other common stimulants like caffeine have a similar effect on the bowels, causing an acceleration of bowel movements. But the research tells a more complicated story.

So, what does the research actually say about smoking and bowel movements? Does it cause diarrhea?

The short answer: We don’t know for sure.

Few direct links have been found between smoking a cigarette and having a bowel movement. But a lot of research has been done on the effects of smoking on inflammatory bowel disease (IBD), of which diarrhea is a major symptom.

The first thing to know is that smoking may make diarrhea symptoms of IBD — like Crohn’s disease, a type of IBD — more severe.

A 2018 review of research on smoking, Crohn’s disease, and ulcerative colitis (another type of IBD) concluded that nicotine therapy may help control the symptoms of ulcerative colitis for former smokers — but it’s only temporary. There’s no long-term benefit. There have also been reports that smoking can actually increase ulcerative colitis activity.

On top of that, researchers note smoking can raise your risk for developing Crohn’s disease. It can also make the symptoms much worse due to inflammation in the intestines.

Moreover, smoking may also raise your risk for bacterial infections that affect the intestines and cause diarrhea.

A 2015 study including more than 20,000 participants published in BMC Public Health found that those who smoke had a higher infection rate of Shigella bacteria. Shigella is an intestinal bacterium often responsible for food poisoning, which leads to diarrhea.

On the other hand, the same study found that smoking causes the stomach to produce more acid, so smokers are less likely to develop Vibrio cholera infections. This is another bacterium that commonly causes infections and diarrhea.

And there’s more research that shows just how uncertain the link is between smoking and bowel movements.

A 2005 study looked at the effects of several stimulants, including coffee and nicotine, on rectal tone. This is a term for the tightness of the rectum, which has an effect on bowel movements.

The study did find that coffee increased rectal tone by 45 percent. It found a very minor (7 percent) increase in rectal tone from nicotine — which was almost as high as the effect by a placebo water pill at 10 percent. This suggests that nicotine may have nothing to do with pooping.

Smoking affects the entire body, including every part of your digestive tract. Here’s what can happen that may cause or worsen diarrhea and other major GI conditions:

  • GERD. Smoking can weaken the esophagus muscles and make stomach acid leak up into the throat. Gastroesophageal reflux disease (GERD) happens when that acid wears away at the esophagus, producing long-term heartburn.
  • Crohn’s disease. Crohn’s is a long-term inflammation of the intestines that can cause symptoms like diarrhea, fatigue, and abnormal weight loss. Smoking can make your symptoms more severe over time.
  • Peptic ulcers. These are sores that form in the stomach lining and intestines. Smoking has a number of effects on the digestive system that can make ulcers worse, but quitting can quickly reverse some of the effects.
  • Colon polyps. These are abnormal tissue growths that form in the intestines. Smoking can double the risk of developing cancerous colon polyps.
  • Gallstones. These are hard buildups of cholesterol and calcium that can form in the gallbladder and cause blockages that may need to be treated surgically. Smoking can put you at risk for gallbladder disease and gallstone formation.
  • Liver disease. Smoking increases your risk for developing nonalcoholic fatty liver disease. Quitting can slow the course of the condition or lower your risk for complications right away.
  • Pancreatitis. This is a long-term inflammation of the pancreas, which helps digest food and regulate blood sugar. Smoking can trigger flare-ups and worsen existing symptoms. Quitting can help you heal faster and avoid long-term symptoms.
  • Cancer. Smoking is linked to numerous types of cancer, but quitting reduces your risk significantly. Cancer from smoking can occur in the:
    • colon
    • rectum
    • stomach
    • mouth
    • throat

Quitting is hard, but not impossible. And quitting sooner rather than later can help you reduce the symptoms that nicotine can cause on your digestive tract and heal your body from its effects.

Try some of the following to help you quit:

  • Make some lifestyle changes. Get regular exercise or meditate to help you break some of the rituals or habits you’ve built around smoking.
  • Encourage your friends and family to support you. Tell those close to you that you plan to quit. Ask if they can check in on you or be understanding of the symptoms of withdrawal.
  • Join a support group with others who have quit smoking to hear their insights and get assistance. There are many online support groups, too.
  • Consider medications for nicotine cravings and withdrawals, such as bupropion (Zyban) or varenicline (Chantix), if needed.
  • Consider a nicotine replacement, like a patch or gum, to help ease yourself out of the addiction. This is known as nicotine replacement therapy (NRT).

So, smoking probably doesn’t make you poop, at least not directly. There’s a whole host of other factors that might be responsible for this sensation of urgency to visit the toilet after smoking.

But smoking does have a major impact on your gut health. It increases your risk for bowel disorders that can cause diarrhea and other GI symptoms.

Quitting can reduce and even reverse some of these effects. Don’t hesitate to try some quitting strategies or reach out for help to break this habit.