Peptic ulcer disease
Smoking causes peptic ulcer disease in people who also are infected with H.pylori, a common bacterial infection. Painful ulcers occur in the stomach and/or the duodenum (the part of the small intestine that connects to your stomach). Smoking is associated with increased risk for complications such as bleeding and perforated ulcers, and a greater risk of dying from the disease. Peptic ulcer disease can be treated, but it is somewhat less successful for people who continue to smoke.
Smoking has a number of effects on the stomach and gut that could promote the development of peptic ulcer disease. For example:
Smoking promotes the reflux of the duodenal contents back into the stomach.
Smoking increases the acidity of the duodenum and makes it more vulnerable to H.pylori infection.
Smoking constricts the small blood vessels in the stomach reducing blood flow. This can lead to damage of stomach tissues and slow down healing of ulcers.
Smoking reduces the production of natural substances that protect the stomach and duodenum from tissue damage.