The myelosuppression period is the period in the chemotherapy cycle when the chemotherapy drugs are used up and the blood cells start to decrease until the blood cell count is completely restored. The myelosuppression period is caused by the inhibition of the normal hematopoietic function of the bone marrow by chemotherapy drugs, and is a relatively dangerous period after chemotherapy. During this period, as the number of white blood cells, red blood cells or platelets in the patient’s blood decreases, even to a very low level, the patient may develop symptoms of anemia such as high fever over 39℃, chest tightness, shortness of breath and panic, or platelet reduction such as nosebleeds and skin mucous membrane bleeding, and in severe cases, serious complications such as infectious shock, anemic heart failure, gastrointestinal or intracerebral bleeding This can lead to the death of the patient. Therefore, during this period, doctors need to use anti-infection, blood transfusion, promote hematopoiesis and other supportive symptomatic treatment to prevent or treat the corresponding complications. The length of the myelosuppression period varies from 1-2 weeks, depending on the patient’s condition and choice of chemotherapy regimen.