Does smoking have a protective effect against ulcerative colitis?

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Last updated: July 7, 2025View editorial policy

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From the Guidelines

Smoking does not have a proven protective effect against ulcerative colitis based on the most recent and highest quality evidence available, and its use is not recommended due to its numerous serious health risks. The relationship between smoking and ulcerative colitis is complex, and while some older studies suggested a potential protective effect of smoking against ulcerative colitis, the most recent evidence does not support this claim. According to the ESPEN practical guideline on clinical nutrition in inflammatory bowel disease 1, the focus should be on dietary recommendations that have been proven to decrease the risk of developing ulcerative colitis, such as a diet rich in fruit and vegetables, rich in n-3 fatty acids, and low in n-6 fatty acids. Some key points to consider include:

  • A diet rich in fruit and vegetables has been associated with a decreased risk of developing ulcerative colitis, with a significant reduction in risk observed in individuals with high intake of dietary fiber, fruits, and vegetables 1.
  • The evidence on the protective effect of smoking against ulcerative colitis is not strong, and smoking is associated with numerous serious health risks, including cardiovascular disease, lung cancer, and other malignancies.
  • The standard treatments for ulcerative colitis include anti-inflammatory medications like 5-aminosalicylates, corticosteroids, immunomodulators, and biologics, which have proven efficacy without the harmful effects of smoking 1. It is essential to prioritize the patient's overall health and well-being, and to recommend evidence-based treatments that have been proven to be effective and safe.

From the Research

Smoking and Ulcerative Colitis

  • Smoking has been found to have a protective effect against ulcerative colitis in several studies 2, 3, 4.
  • The active substance responsible for this protective effect is believed to be nicotine, which affects colonic mucus, intestinal permeability, and cellular immunity 2.
  • Transdermal nicotine has been shown to be effective in treating active ulcerative colitis, although it can cause side effects such as contact dermatitis, nausea, and lightheadedness 3.
  • Topical administration of nicotine to the colon may reduce side effects and be of clinical benefit 3.

Mechanisms and Effects

  • The exact mechanisms by which smoking and nicotine exert their protective effects on ulcerative colitis are still unknown, but it is thought that nicotine may play a role in reducing inflammation and improving symptoms 4, 5.
  • Smoking cessation, on the other hand, may aggravate ulcerative colitis and improve Crohn's disease 4.
  • The relationship between smoking and ulcerative colitis is complex, and the potential benefits of smoking must be weighed against the risks of other smoking-related diseases 6.

Clinical Implications

  • While nicotine may have a protective effect against ulcerative colitis, its use as a treatment is limited by its side effect profile and poor patient tolerability 5.
  • Further research is needed to fully understand the relationship between smoking, nicotine, and ulcerative colitis, and to develop effective and safe treatments for the disease 5, 6.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

[Tobacco and inflammatory bowel disease].

La Tunisie medicale, 2000

Research

Smoking in inflammatory bowel diseases: good, bad or ugly?

World journal of gastroenterology, 2007

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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