Smoking is harmful to the gastrointestinal tract, and common hazards include gastritis, gastric ulcer, reflux esophagitis and other diseases, and long-term smoking may also lead to gastrointestinal cancer. 1. Gastritis and gastric ulcer: the tar of smoking will damage the capillaries of the stomach and reduce the protective function of the gastric mucosa, so that gastric acid and Helicobacter pylori can easily erode the gastric mucosa, resulting in the emergence of gastritis and gastric ulcer. 2. Reflux esophagitis: Smoking may also lead to relaxation of cardia sphincter, resulting in reflux esophagitis. 3. Gastrointestinal cancer: Smoking can damage the gastrointestinal mucosa, and if you smoke for a long time, the gastrointestinal mucosa will be stimulated for a long time, which will lead to the development of gastrointestinal mucosa cancer. Smoking also has different degrees of damage to other parts of the body, so it is recommended to try not to smoke.