Cyclophosphamide (CP), also known as cytophosphane among other names, is a medication used as chemotherapy and to suppress the immune system. As chemotherapy it is used to treat lymphoma, multiple myeloma, leukemia, ovarian cancer, breast cancer, small cell lung cancer, neuroblastoma, and sarcoma. As an immune suppressor it is used in nephrotic syndrome, granulomatosis with polyangiitis, and following organ transplant, among other conditions. It is taken by mouth or injection into a vein. Most people develop side effects. Common side effects include low white blood cell counts, loss of appetite, vomiting, hair loss, and bleeding from the bladder. Other severe side effects include an increased future risk of cancer, infertility, allergic reactions, and pulmonary fibrosis. Cyclophosphamide is in the alkylating agent and nitrogen mustard family of medications. It is believed to work by interfering with the duplication of DNA and the creation of RNA. Cyclophosphamide was approved for medical use in the United States in 1959. It is on the World Health Organization's List of Essential Medicines. Medical uses Cyclophosphamide is used to treat cancers and autoimmune diseases. It is used to quickly control the disease. Due to its toxicity, it is replaced as soon as possible by less toxic drugs. Regular and frequent laboratory evaluations are required to monitor kidney function, avoid drug-induced bladder complications and screen for bone marrow toxicity. Cancer The main use of cyclophosphamide is with other chemotherapy agents in the treatment of lymphomas, some forms of brain cancer, neuroblastoma, leukemia and some solid tumors. Oncovet C (Chemovet S.A.), is the first-based drug approved in Latin America for veterinary use for canine and feline cancer (carcinomas of anal sacs, bladder carcinomas, urethral carcinomas, hemangiosarcomas, lymphomas, mast cell tumor, osteosarcomas, soft tissue sarcoma), feline cancers (mammary carcinomas, hemangiosarcomas, lymphomas, plasmacytomas, chronic lymphocytic leukemia, acute myelogenous leukemia, mast cell tumor). It can be administered in different treatment schemes, such as induction therapy, adjuvant, neoadjuvant, maintenance and metronomic chemotherapy. Autoimmune diseases Cyclophosphamide decreases the immune system's response, and although concerns about toxicity restrict its use to patients with severe disease, it remains an important treatment for life-threatening autoimmune diseases where disease-modifying antirheumatic drugs (DMARDs) have been ineffective. For example, systemic lupus erythematosus with severe lupus nephritis may respond to pulsed cyclophosphamide. Cyclophosphamide is also used to treat minimal change disease, severe rheumatoid arthritis, granulomatosis with polyangiitis, Goodpasture syndrome and multiple sclerosis. Because of its potential side effects such as