Radiotherapy is a relatively common local antitumor treatment. Radiotherapy may trigger local reactions, such as local skin burns, due to the thermal effects of radiotherapy. Radiotherapy may cause systemic reactions such as bone marrow suppression, decreased white blood cells, anemia, and decreased platelets. In addition, radiotherapy can trigger different reactions depending on the location. Radiotherapy to the lung and chest, such as breast cancer and lung cancer, may trigger radioactive pneumonia, with symptoms such as cough, coughing and fever. Radiotherapy to the pelvic area, most commonly radiotherapy to cervical cancer and ovarian tumors, may cause radiation enteritis leading to diarrhea, frequent stools and poor bowel control. The adverse reactions caused by radiotherapy can be improved with symptomatic treatment. The course of radiotherapy is relatively long and needs to strengthen nutrition.