1. Health
You can opt-out at any time. Please refer to our privacy policy for contact information.

What Smoking Does to Your Guts

Your lungs aren't the only things that suffer from smoking.


Updated: January 04, 2008

Cigarette smoking affects all parts of the body, including the digestive system. This is especially damaging because the digestive system processes the food we eat into substances that are needed for the body to function properly.

Crohn's Disease

Smoking cigarettes has a negative effect on Crohn's disease. People who smoke, or who have smoked in the past, have been shown to have a higher risk of developing Crohn's disease than non-smokers. Crohn's disease patients who smoke have an increased number of relapses and repeat surgeries, as well as more of a need for aggressive and immunosuppressive treatment. No one knows why smoking worsens Crohn's disease. It is theorized that smoking may decrease blood flow to the intestines or trigger a response in the immune system. Even after quitting smoking, there is still a risk of Crohn's disease to the former smoker. However, people with Crohn's disease may have a milder disease course if they stop smoking for more than one year.


Heartburn can also be caused by smoking. A valve at the end of the esophagus (the lower esophageal sphincter, or LES) normally keeps stomach acids from coming back up into the esophagus. The LES is weakened by smoking, which results in stomach acid being able to enter the esophagus and cause heartburn. Smoking also seems to harm the esophagus directly, which hinders its ability to resist damage. Additionally, smoking interferes with the movement of bile salts. Bile salts move from the intestine to the stomach. When this does not occur (a disease called duodenogastric reflux) the stomach acid becomes more acidic and can further damage the esophagus.


Another organ in the digestive tract that is adversely affected by smoking is the liver. The liver is an important organ which filters toxins from the body. These toxins include medications and alcoholic beverages. The function of the liver may be hindered by cigarette smoke. When this happens, a different dose of medication is needed to achieve the desired effect on an illness or disease. Smoking can also aggravate existing liver disease caused by alcoholism.

Peptic Ulcer

Smokers have a higher chance of developing an ulcer. If a smoker gets an ulcer, it typically takes longer to heal and is more fatal than those of nonsmokers. No one is certain about why this is so, but it could be due to the variety of effects smoking has on the digestive tract. Smoking decreases the amount of sodium bicarbonate produced by the pancreas. Without it, stomach acid is not neutralized in the duodenum (first part of the small intestine). This could contribute to ulcers forming in the duodenum. Also, smoking may cause an increase in the amount of stomach acid that is flowing into the duodenum.


Smoking causes serious and sometimes irreversible damage to the digestive tract. It's estimated that 400,000 people die each year as a result of smoking cigarettes. These deaths, and the suffering that precedes them, are completely preventable.


The National Digestive Diseases Information Clearinghouse. "Smoking and Your Digestive System." National Institute of Diabetes and Digestive and Kidney Diseases Feb 2006. 05 Jul 2007.

Cosnes J, Beaugerie L, Carbonnel F, Gendre JP."Smoking cessation and the course of Crohn's disease: an intervention study." Gastroenterology Apr 2001. 05 Jul 2007.

Yamamoto T. "Factors affecting recurrence after surgery for Crohn's disease." World J Gastroenterol 14 Jul 2005. 05 Jul 2007.

Amber J. Tresca
About.com Inflammatory Bowel Disease (IBD)

©2014 About.com. All rights reserved.

We comply with the HONcode standard
for trustworthy health
information: verify here.