The links between smoking and lung damage are well documented, but smoking also damages other organs in the body, including the gastrointestinal tract.

If you are a smoker, every time you light up you are introducing harmful chemicals into your lungs, which are circulated throughout your body. There are more than 1000 of these chemicals in tobacco smoke, including nicotine, carbon monoxide and free radicals. These can bring about changes in the bacteria that live in your gut, as well as impacting your immune system and affecting gene function.


Today, 31 May 2019, is World No-Tobacco Day, organised by the World Health Organisation. This event is observed around the globe as a 24-hour abstinence from tobacco products and is a campaign to raise awareness of the risks of smoking. GI Doctors provide information below about how smoking effects two common disorders, IBS and IBD.


Smoking and Irritable Bowel Syndrome

If you have Irritable Bowel Syndrome you gastrointestinal tract often becomes very sensitive and susceptible to certain triggers, including tobacco. Smoking is likely to cause heartburn and reflux, which are already common in IBS and so are likely to worsen.

It may damage the oesophageal sphincter, allowing stomach acid to flow upwards and into the oesophagus. Nicotine results in an over-production of stomach acid and decreases production of sodium bicarbonate, resulting in a significant worsening of certain IBS symptoms. Smoking may also increase the chances of developing peptic ulcers and the chance of ulcers perforating goes up by as much as 10 times.


Smoking and Inflammatory Bowel Disease

The relationship between smoking and Inflammatory Bowel Diseases is a complex one.

Crohn’s Disease

Smoking has been shown to increase the risk of Crohn’s disease and may worsen the condition. People with Crohn’s who smoke tend to have more flare-ups and their symptoms can be more severe. They are also at risk of more complications, such as narrowing of the bowel which can be dangerous. Fistulas are also a greater risk for smokers with Crohn’s disease.

If you give up smoking, after a year your chances of a flare-up are the same as someone with Crohn’s who has never smoked. Your risk of surgery also decreases if you quit as does the chance of the disease recurring after surgery.

Ulcerative Colitis

In the case of ulcerative colitis, it is more of a mixed picture. Research has shown that smokers are less likely to develop the condition than non-smokers. Some people who give up smoking go on to develop ulcerative colitis.

Scientists are unclear why this is but they believe that nicotine may be responsible. People with ulcerative colitis often have a thinner mucus layer in the colon and rectum compared to healthy people. The presence of nicotine in the body may serve to increase the production of this mucus.

Nicotine may also suppress the immune system and prevent inflammation in the colon. Some researchers believe that nitric oxide, which is released by nicotine, may reduce the activity of muscles in the colon, helping to relieve the urgent need to go to the toilet. Smoking can also change the way a person’s genes are expressed and because ulcerative colitis has a genetic component, this may help to prevent the development of the disease.

While this may tempt some people into continuing (or even taking up) smoking to help with ulcerative colitis, the risks of smoking remain high. It increases your risk of many different types of cancer, as well as heart disease and chronic bronchitis. Healthcare professionals strongly advise against such drastic action.

There is some evidence that nicotine replacement therapy or nicotine patches may help with the management of the disease in some cases but, again, the results are mixed and you should discuss this with a gastrointestinal specialist before choosing. Many studies point to the fact that nicotine is no more effective than conventional drug treatments for inflammatory bowel disease, such as aminosalicylates and steroids.


Bowel Cancer Risk

Smoking introduces carcinogens into the entire body, including the colon, increasing the risk of colorectal cancer.

There are many excellent services available to help you quit smoking including the NHS’ excellent Smokefree service. If you have IBS or IBD or are concerned about any gastrointestinal symptoms, talk to us for advice and support.


Working with a specialist that can promptly diagnose and monitor your symptoms, will give you the best chance to get back to feeling your best.