How long it takes for low white blood cells to become normal is mainly related to the primary disease that causes leukopenia, which may take a few days or about half a year, and if caused by malignant hematologic diseases such as acute leukemia, it may take a longer time to recover. 1. If the leukopenia is due to bacterial infection, it will return to normal in 7-10 days through active treatment (levofloxacin); 2. if the infection is caused by a virus, recovery can be achieved through antiviral treatment (ganciclovir) in about 14 days; 3. in the case of autoimmune diseases such as systemic lupus erythematosus, recovery can be achieved by treatment (prednisone) in about 1 month, and the recovery time may be prolonged if the treatment is not effective; 4. If it is caused by blood system diseases such as aplastic anemia, if it is treated effectively by oral cyclosporine and other treatments, it will return to normal after about six months of treatment. However, if it is caused by acute leukemia, etc., it may take a longer time to return to normal, and the treatment drugs include cytarabine and Zoerythromycin. Low white blood cells should first clarify the cause of the decrease, and then according to the specific situation of their own, under the treatment of professional doctors to receive treatment.