Bleomycin injection is an antineoplastic medication used to treat various types of cancer. It is a type of chemotherapy drug and works by damaging the DNA of cancer cells, which leads to their death. It is usually administered intravenously (IV) or intramuscularly (IM). It may also be used to treat certain non-cancerous conditions such as warts and hydrocephalus. Common side effects of bleomycin include hair loss, nausea, vomiting, and mouth sores.