Radiotherapy may cause vomiting. Whether radiotherapy can cause vomiting is mainly related to the site of radiotherapy and the dose of radiotherapy. In the case of radiotherapy for stomach cancer patients, radiotherapy may cause radiation gastritis, which may cause vomiting. If radiotherapy is given to tissues and organs around the stomach, the stomach may also be damaged, especially the higher the dose, the greater the damage to the stomach, which may also cause vomiting. In case of cranial radiotherapy, cerebral edema may increase during radiotherapy, which may also aggravate vomiting. If the site of radiotherapy is far from the digestive tract, it will not cause vomiting.