Etoposide is a chemotherapy medication primarily used to treat various types of cancer, including lung cancer and testicular cancer. It works by inhibiting the enzyme topoisomerase II, which is essential for DNA replication and cell division. By disrupting these processes, etoposide helps to slow down or stop the growth of cancer cells. Etoposide is usually administered intravenously or in capsule form. Common side effects may include nausea, vomiting, hair loss, and an increased risk of infection due to its impact on the immune system. Patients receiving etoposide are often monitored closely for any adverse reactions during treatment.