Crohn’s Disease And Smoking

What is Crohn’s disease?

Crohn's disease inflammatory disorder of the bowels  (or IBD) which causes inflammation of the tissues in your gastrointestinal tract, which can result in stomach discomfort, severe diarrhoea, exhaustion, weight loss and malnutrition.

Crohn's disease-related inflammation can affect different parts of the digestive system, frequently, the small intestine. This inflammation frequently extends into the deeper parts of the bowel. The inflammation in Crohn’s disease is induced by an uncontrollable immunological response to gastrointestinal bacterial antigens. Immune cells  (T-cells, B-cells, monocytes) are implicated in this process since they invade the abdomen of the patient1. This inflammatory response frequently results in irreparable tissue damage, such as an intestinal ulcer or abdominal abscesses leading to the disease symptoms. 


Without therapy, Crohn's disease symptoms may be persistent or sporadic, occurring every few weeks or months. A flare-up or relapse occurs when the symptoms return. Remissions are the intervals between flare-ups. The main symptoms of the disease include:

  • Diarrhoea, which might happen abruptly
  • Stomach pains, usually in the lower-right portion of the stomach
  • Blood in stools
  • Exhaustion (fatigue)
  • Weight loss

Some people with Crohn’s disease also have other symptoms such as:

  • Fever
  • Feeling unwell
  • Joint aches
  • Sore eyes
  • Reddish skin areas, typically on the legs
  • Mouth ulcers

In children, there will be signs of malnutrition as most of the nutrients/calories needed for their normal growth will be maximally utilized due to the inflammatory process.

The effects of smoking on Crohn’s Disease

Smoking is a risk factor

Smoking is a  preventable risk factor for several illnesses, including Crohn's disease. According to research,2 smokers are more susceptible to the disease than non-smokers. The interaction between smoking and the immune system, as well as other genetic and environmental factors, is most likely responsible for the higher risk. More than 1,000 substances are included in tobacco smoke, including nicotine, carbon monoxide, and free radicals. These substances can have a variety of effects on the gastrointestinal tract. Smoking can alter the bacteria that dwell in the gut, impact how a person's genes operate and create immune system changes, all of which may increase a person's risk of developing Crohn's disease.3

Smoking can trigger a flare-up

Research has also shown that smoking increases the frequency of the symptoms;  a study in the USA4 showed that non-smokers with Crohn’s disease have symptoms approx. five days in a month compared to smokers who have up to 2 weeks in a month. Smoking induces cell death in the epithelial lining of the gastrointestinal system and also inhibits epithelial cell renewal. All these can trigger a flare-up and worsen the symptoms of the disease. 

Smoking can make the symptoms worse

Symptoms of the disease can be made worse if the person is a smoker.

People with Crohn's disease who smoke may experience:3

  • Strictures or intestinal narrowing that can cause dangerous blockages.
  • They are more likely to develop fistulas, which are irregular pathways in the body that frequently necessitate surgery.
  • Have more flare-ups.
  • Require more immunosuppressive medicines, such as steroids and biologic therapies, and these drugs are not always as successful in smokers.
  • Are more likely to need frequent surgeries
  • Extraintestinal symptoms (additional issues in other regions of the body), such as osteoporosis (weak bones), osteoarthritis, skin diseases, and eye problems are more prone to occur.

Tips for quitting smoking

To quit smoking is one of the most effective ways to control Crohn's disease. It is as effective as immunotherapy medications in treating Crohn's disease and keeping it in remission. Smoking cessation decreases your chance of having  Crohn's disease relapse or flare up.5 

Quitting smoking is not simple. The extremely addictive nature of nicotine makes it difficult to quit. When you try to quit, withdrawal symptoms such as restlessness and anxiety might cause you to relapse. You'll have a higher chance of stopping smoking if you get assistance from your doctor or a smoking cessation counsellor.


Cigarette smoking raises the risk of Crohn's disease and is linked to a more aggressive disease course, increased symptom frequency, failure to respond to medical therapy, the necessity for surgery, and postoperative complications. Complications of illness and/or therapy are more prevalent in smokers than in non-smokers (for example, cancer, osteoporosis, postoperative wound disintegration). As a result, it is vital for Crohn's disease patients who smoke to stop smoking since it is extremely detrimental to their health and disease prognosis.


  1. Petagna L, Antonelli A, Ganini C, Bellato V, Campanelli M, Divizia A, et al. Pathophysiology of Crohn’s disease inflammation and recurrence. Biol Direct [Internet]. 2020 [cited 2022 Sep 19]; 15(1):23.
  2. Parkes GC, Whelan K, Lindsay JO. Smoking in inflammatory bowel disease: Impact on disease course and insights into the aetiology of its effect. Journal of Crohn’s and Colitis [Internet]. 2014 [cited 2022 Sep 19]; 8(8):717–25.
  3. Smoking-and-IBD.pdf [Internet]. [cited 2022 Sep 19].
  4. GAS018_Smoking_and_Crohns_Disease.pdf [Internet]. [cited 2022 Sep 19].
  5. 5. Wilson A. Smoking cessation strategies in Crohn’s disease. Frontline Gastroenterol [Internet]. 2011 [cited 2022 Sep 20]; 2(1):10–2.

Innocent Chijioke

Bachelor of Medicine, Bachelor of Surgery - MBBS, Medicine, University of IbadanUniversity of Ibadan, Nigeria

Innocent Dike is a final-year medical student at the University of Ibadan, Nigeria. He has more than two years of experience in research and health blog article writing. He serves as an ambassador for i-medics, where he trains his peers on blog article writing. presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
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