Aplastic anemia (referred to as reanemia) is a group of diseases characterized by hematopoietic stem cell damage, peripheral blood and whole blood cell reduction due to chemical, physical and biological factors and unexplained bone marrow hematopoietic failure. Symptoms are mainly manifested by severe anemia, bleeding and infection. The disease is more common in young adults and more common in men than women. The drugs that cause aplastic anemia are: 1.Anti-tumor drugs Azacitidine hydrochloride, cyclophosphamide, isocyclophosphamide, mitomycin, methotrexate, mercaptopurine, piroplasin, etc. can inhibit the hematopoietic function of bone marrow and cause reblast. 2, antibacterial drugs chloramphenicol has myelosuppressive toxicity, which can lead to reoccurrence, and is irreversible, independent of the dose used. Severe cases can often be life-threatening. Other antibacterial drugs include tetracyclines, streptomycin, amphotericin B, sulfonamides, isoniazid (remifentan) also have inhibitory effect on bone marrow. 3, antipyretic and antirheumatic drugs indomethacin (anti-inflammatory pain), aminopyrine, aspirin, pau taisong, diclofenac, colchicine, kinolphine. 4.Anti-gout drug Allopurinol. 5.Sedative, hypnotic and antiepileptic drugs Chlordiazepoxide (Librium), chlorpromazine, phenytoin sodium, carbamazepine, etc. 6.Anti-thyroid drugs methimazole (tabazol), carbimazole (methylphenidate), propylthiouracil. 7.Anti-malarial drugs: chloroquine, hydroxychloroquine, primaquine, ethamiprid. 8.Anti-platelet aggregation drugs Ticlopidine. In order to prevent drug-induced aplastic anemia, the following points should be noted 1. Rational use of drugs, familiar with the characteristics of the action and adverse reactions of various types of drugs, certain drugs that damage the hematopoietic system should be aware of their seriousness, and be used with caution or not. 2.Strictly grasp the indications, especially chloramphenicol, and try not to use the drug if it can be replaced by other drugs. 3. Strictly observe the blood items during the drug use, and do bone marrow examination if necessary, and discontinue the drug as soon as abnormalities are found.