Why Do Cigarettes Worsen Crohn's and Help UC?

  • Medical Author:
    Dennis Lee, MD

    Dr. Lee was born in Shanghai, China, and received his college and medical training in the United States. He is fluent in English and three Chinese dialects. He graduated with chemistry departmental honors from Harvey Mudd College. He was appointed president of AOA society at UCLA School of Medicine. He underwent internal medicine residency and gastroenterology fellowship training at Cedars Sinai Medical Center.

Ask the experts

I have Crohn's disease and I heard that smoking was bad for a Crohn's patient, however, for a patient with colitis ulcer, "nicotine" could have a positive effect on the colitis ulcer. Can you confirm this, and explain this please? Thank you for your answer. I like the MedicineNet a lot and have been using it to learn more about my own disease. We do not have anything like this here in Denmark.

Doctor's response

It has been reported in many studies that cigarette smoking causes Crohn's disease to become worse yet causes ulcerative colitis to become better. The reason for this is unknown. One must also keep in mind that although smoking may be slightly beneficial for ulcerative colitis, it increases the risk of lung and cardio-vascular disease for both the individuals who smoke and others around him or her.

Medically reviewed by John A. Daller, MD; American Board of Surgery with subspecialty certification in surgical critical care


"Clinical manifestations, diagnosis and prognosis of Crohn disease in adults"

"Clinical manifestations, diagnosis, and prognosis of ulcerative colitis in adults"

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Reviewed on 6/9/2017