Chemotherapy generally produces a number of side effects, which often cause patients to feel unwell or show abnormalities in their tests. Generally, the time to recover from these symptoms and abnormalities is not the same, but most of them do not take more than one month. A few patients take longer to recover, and very few patients do not return to normal completely. Some uncomfortable symptoms will disappear quickly, for example, allergic reactions caused by chemotherapy drugs, patients may experience itchy skin, even breathing difficulties and other uncomfortable symptoms, usually recover within 1-2 days after stopping the drug or giving anti-allergy treatment. Gastrointestinal side effects such as nausea, vomiting, and diarrhea usually resolve slowly within 2-3 days after the end of chemotherapy, with the longest lasting usually not exceeding 1 week. Some chemotherapy side effects may take longer to recover, such as bone marrow suppression after chemotherapy resulting in blood tests showing a decrease in the number of white blood cells, red blood cells, and platelets, which usually reaches its most severe level 7-10 days after chemotherapy. Recovery begins 2 weeks after the cessation of chemotherapy and generally returns to normal in most patients before the time for the next cycle of chemotherapy arrives, with a total recovery time of no more than 1 month. It is important to note that a small number of specific chemotherapy side effects may take months, or even years, to return to normal. A very small number of patients may never fully return to normal, leaving so-called after-effects. For example, phytochemical chemotherapy drugs can damage peripheral nerves, resulting in paralysis and abnormal sensation in the hands and feet. Some patients can return to normal within three months after stopping the drugs and with symptomatic treatment, while others may take half a year or even longer to recover, and a very small number of patients do not recover completely and need to take medication for life in order to maintain.