Stomach pain from smoking is associated with gastritis, gastric ulcer, esophagitis and other diseases. Cigarettes release nicotine and tar during the burning process, which are carcinogenic and have certain irritating properties. Smoke not only passes through the lungs, but also enters the stomach. Tobacco contains a lot of harmful substances, which can affect the contraction of blood vessels in the stomach wall. Stomach wall cells due to blood supply problems, so the mucosal resistance gradually decreased, long-term will be more likely to suffer from gastritis, gastric ulcers and other diseases. When suffering from gastritis, gastric ulcer and other diseases, the irritating substances in tobacco, will directly cause violations of the stomach mucosa. The gastric mucosa will spasm and contract when irritated, thus causing stomach pain. The nicotine in tobacco also causes relaxation of the cardia sphincter, which makes it easier for stomach acid to reflux through the cardia into the esophagus, triggering an attack of reflux esophagitis. When suffering from esophagitis, the patient may also experience pain in the stomach.