Reserpine is primarily used in the treatment of high blood pressure (hypertension). It works by decreasing the levels of certain chemicals in the brain, such as catecholamines (norepinephrine, dopamine, and serotonin), which helps to relax blood vessels and reduce blood pressure. Additionally, it is sometimes prescribed for managing symptoms of certain psychiatric disorders, such as schizophrenia, by helping to stabilize mood and reduce agitation. In veterinary medicine, reserpine is also utilized to calm aggressive or overly excitable animals. Its ability to deplete catecholamines makes it effective in these applications, though it is often used with caution due to potential side effects.