How does smoking affect Crohn’s Disease?
In numerous studies, half or more of the adults with Crohn’s Disease were smokers when they were diagnosed. This suggests that people who smoke are more likely to get Crohn’s than those who do not smoke.
Research also suggests that smoking can make Crohn’s Disease worse. People with Crohn’s who smoke may find that they:
- have more severe symptoms and complications such as strictures and fistulas
- have more flare-ups
- require more steroids and stronger drugs such as immunosuppressants and biologics. Sometimes these drugs are not as effective in people who smoke,
- are more likely to need surgery
- and are more likely to have to return for further surgery
Some studies suggest that women who smoke are more likely to develop Crohn’s Disease and to require surgery than men who smoke. Smoking has also been shown to have an association with disease location. Smokers tend to have Crohn’s Disease in the small intestine (small bowel) rather than the colon (large bowel). Fundamental differences in the functions of the small and large bowel may explain this.
HOW DOES SMOKING MAKE YOU SUSCEPTIBLE TO CD?
We do not know, although there are lots of theories. Tobacco smoke contains over a thousand different chemicals including nicotine, carbon monoxide, and free radicals. There are several possible ways in which smoking may affect the gut – it may lower the intestines’ defenses, decrease the blood flow in the intestines, or cause changes to the immune system which result in inflammation.
WHAT ABOUT THE RISK OF PASSIVE SMOKING?
Studies into the effect of passive smoking on Crohn’s Disease are inconclusive. However, some studies suggest that children and unborn babies exposed to passive smoking may be more likely to develop Crohn’s Disease.
Smoking during pregnancy is not advised for anyone whether or not they have Crohn’s, due to the risks to the unborn baby.
IF I AM A SMOKER NOW, IS IT WORTH GIVING UP?
Both research and health professionals agree that giving up smoking is beneficial for people with Crohn’s Disease. The guidelines for people with Crohn’s Disease strongly recommend that people with Crohn’s do not smoke.
In the non-smoker, Crohn’s seems milder. Once you have stopped smoking for one year, the chances of a flare-up may be as low as for someone with Crohn’s who has never smoked. One study showed that people who continued to smoke were over twice as likely to have a flare-up compared to people who had stopped smoking.
Smokers also appear to have a greater need for some of the stronger forms of medical treatment such as immunosuppressant drugs. People who stop smoking are less likely to need repeated surgery compared with people who continue smoking after surgery.
Even just reducing the amount you smoke may have a positive effect on your symptoms. A recent study showed that heavy smokers have more structures, and are more likely to need a resection than people who do not smoke as much. This suggests that, although completely stopping smoking has the best outcome, reducing the amount you smoke can also help. However, even light smokers with CD have more active disease and a greater hospitalization rate.
