Leukemia can cause vomiting. There are two reasons why leukemia patients experience vomiting: one is caused by the leukemia itself. If the white blood cell count in leukemia patients abnormally increases to more than 100×10^9/L, this condition is called hyperleukocytosis. In the state of hyperleukocytosis, the body is in a state of ischemia and hypoxia, which can manifest as dizziness, headache, and vomiting in the nervous system. The other reason is that during chemotherapy, the use of chemotherapy drugs can lead to gastrointestinal reactions such as nausea and vomiting.