Cyclophosphamide is used alone or in combination with other medications to treat Hodgkin's lymphoma (Hodgkin's disease) and non-Hodgkin's lymphoma (types of cancer that begin in a type of white blood cells that normally fights infection); cutaneous T-cell lymphoma (CTCL, a group of cancers of the immune system that first appear as skin rashes); multiple myeloma (a type of cancer of the bone marrow); and certain types of leukemia (cancer of the white blood cells), including chronic lymphocytic leukemia (CLL), chronic myelogenous leukemia (CML), acute myeloid leukemia (AML, ANLL), and acute lymphoblastic leukemia (ALL). It is also used to treat retinoblastoma (cancer in the eye), neuroblastoma (a cancer that begins in nerve cells and occurs mainly in children), ovarian cancer (cancer that begins in the female reproductive organs where eggs are formed), and breast cancer. Cyclophosphamide is also used to treat nephrotic syndrome (a disease that is caused by damage to the kidneys) in children whose disease has not improved, has gotten worse, or has come back after taking other medications or in children who experienced intolerable side effects with other medications. Cyclophosphamide is in a class of medications called alkylating agents. When cyclophosphamide is used to treat cancer, it works by slowing or stopping the growth of cancer cells in your body. When cyclophosphamide is used to treat nephrotic syndrome, it works by suppressing your body's immune system.