Am J Gastroenterol  1998 Feb;93(2):144-9 

Inflammatory bowel disease and smoking--a review.

Thomas GA, Rhodes J, Green JT.

Department of Gastroenterology, University Hospital of Wales, Cardiff, United

Kingdom.

The relationship between smoking and inflammatory bowel disease is a curious but

well-established one. It is negatively associated with ulcerative colitis but

positively associated with Crohn's disease. It also has opposite influences on

the clinical course of the two conditions with possible beneficial effect in

ulcerative colitis and detrimental effect in Crohn's disease. The diametrically

"opposite" relationship of smoking status with the two conditions has been the

subject of much interest in the hope that it may reveal pathogenic mechanisms

responsible for the two conditions and possibly offer the key to alternative

therapeutic options. Nicotine may be the principal agent in smoking responsible

for the association; trials have shown it to be of some benefit in ulcerative

colitis, but further research is required to establish its therapeutic role and

possible mechanisms of action. In this article, we review the historical,

clinical, and therapeutic aspects of the association between smoking and

inflammatory bowel disease.