A white blood cell count of 2.9 x 10^9/L is low, and the severity of the condition needs to be combined with the symptoms of the cause, which can be treated with medications such as leukocyte boosters. The normal range of white blood cell count is 4.0 to 10.0 x 10^9/L, and leukopenia is diagnosed when it is lower than 4.0 x 10^9/L. Common causes include drug factors, immune system disorders, and hematologic disorders. Common causes include drug factors, immune system disorders, and hematologic tumors. 1. Some common drugs such as antipyretic and analgesic (ibuprofen), antibiotics (chloramphenicol, penicillin), anti-tuberculosis drugs (rifampicin, isoniazid), and anti-tumor drugs (paclitaxel) can cause leukopenia. If there is a clear history of drug use and the white blood cell count is 2.9×10^9/L, it is usually not serious, and most of them can be recovered by stopping the related drugs in time according to the doctor’s instructions, and additional drugs are usually not needed. 2. Immune system diseases, such as systemic lupus erythematosus, can produce immune antibodies, causing a decrease in white blood cell count. If the white blood cell count is 2.9×10^9/L, the condition is relatively serious, and immunotherapy can be used in conjunction with leukocyte-boosting drugs (Diyu Lianbai Tablets) to raise the white blood cell count and prevent infection. 3. Blood system tumors, such as leukemia, myeloma, metastatic tumor, will affect the hematopoietic function of bone marrow, causing low white blood cell count. When diagnosed, the condition is very serious, requiring systematic anti-cancer treatment, and the effect of simple white blood cell boosting drugs is often poor. For people with white blood cell count of 2.9×10^9/L, it is recommended to consult a doctor in time to find out the cause of the disease and follow the doctor’s instructions for treatment, and the use of medication should be carried out under the guidance of a professional doctor.