Pancytopenia is a medical condition in which there is a reduction in the number of red and white blood cells, as well as platelets. If only two parameters from the complete blood count are low, the term Bicytopenia can be used. The diagnostic approach is the same as for pancytopenia. Iatrogenic causes of pancytopenia include chemotherapy for malignancies if the drug or drugs used cause bone marrow suppression. Rarely, drugs (antibiotics, blood pressure medication, heart medication) can cause pancytopenia. The antibiotics Linezolid and Chloramphenicol can cause pancytopenia in some individuals. Rarely, pancytopenia may have other causes, such as mononucleosis, or other viral diseases. Increasingly, HIV is itself a cause of pancytopenia. The mechanism for pancytopenia differ according to the etiology for example in hemophagocytic lymphohistiocytosis (HLH) there is marked inappropriate and ineffective T cell activation that leads to an increased hemophagocytic activity. The T cell activated macrophages engulf erythrocytes, leukocytes, platelets, as well as their progenitor cells. Along with pancytopenia, HLH is characterized by fever, splenomegaly, and hemophagocytosis in bone marrow, liver, or lymph nodes. Pancytopenia usually requires a bone marrow biopsy in order to distinguish among different causes. Treatment of the underlying cause. Blood transfusion (PRBC) may be indicated according to need.