Nausea and vomiting after smoking are associated with diseases such as gastritis and gastric ulcer. Tobacco contains a large amount of toxic substances, such as nicotine and tar. In the process of smoking, these toxic substances will not only cause damage to the lungs, but also part of the toxic substances will enter the digestive system and cause irritation to the gastric mucosa. In a state where the gastric mucosa is intact, the toxic substances cause relatively little damage to the gastric mucosa, but some people have gastritis and gastric ulcers in their stomachs. The toxic substances in tobacco, in addition to causing irritation to the stomach wall, will also affect the blood circulation of the stomach wall, which is not conducive to the repair of the gastric mucosa, so during the illness of gastritis and gastric ulcer, it is best not to smoke, otherwise it will affect the effectiveness of treatment.