Rectal cancer preoperative chemotherapy twice is more likely to have side effects brought by drugs than the first time, and patients may have nausea, vomiting, fever, fatigue, pain in limbs and other symptoms. 1. Local irritation: after infusion of more aggressive drugs, it may cause phlebitis, and necrosis of local tissues also occurs when these drugs ooze out. 2. Systemic reactions: mainly including fever, fatigue, dizziness, headache and so on. 3. Gastrointestinal reactions: more common, such as nausea, vomiting, loss of appetite, diarrhea and so on. 4. Hematological reactions: chemotherapy can cause a decrease in white blood cells, red blood cells, hemoglobin or platelets, which makes patients prone to infections and bleeding symptoms. 5. Damage to peripheral nerves: patients will start to have pain at the ends of hands and feet, erythema, dullness of sensation, etc., and some serious patients may be accompanied by flaking and ulceration. Preoperative chemotherapy for rectal cancer can help reduce the clinical stage of the tumor, create surgical opportunities and improve the long-term survival rate. Symptoms appearing twice in preoperative chemotherapy for rectal cancer are related to the specific medication used by the patients and their individual physique. If related symptoms appear, please seek medical treatment in time to avoid delaying the condition and affecting the treatment.