Cytarabine, also known as Ara-C, is a chemotherapy medication used primarily to treat certain types of leukemia, particularly acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). It is a nucleoside analog that interferes with DNA synthesis, thereby inhibiting the proliferation of cancer cells. Cytarabine is typically administered intravenously or subcutaneously and may be used in various dosing regimens depending on the specific treatment protocol. Side effects can include nausea, vomiting, and myelosuppression, which is a decrease in bone marrow activity.