Cytarabine is a chemotherapy medication primarily used to treat certain types of cancer, particularly leukemia and lymphoma. It works by interfering with the growth and reproduction of cancer cells, ultimately leading to their death. Cytarabine is often administered through injection, either into a vein or under the skin. This drug is part of a broader class of medications known as antimetabolites, which mimic the building blocks of DNA and RNA. While effective, cytarabine can cause side effects, including nausea, hair loss, and an increased risk of infection due to its impact on the immune system.