Selegiline is used to help control the symptoms of Parkinson’s disease (PD; a disorder of the nervous system that causes difficulties with movement, muscle control, and balance) in people who are taking levodopa and carbidopa combination (Sinemet). Selegiline may help people with Parkinson’s disease by decreasing the dose of levodopa/carbidopa needed to control symptoms, stopping the effects of levodopa/carbidopa from wearing off between doses, and increasing the length of time that levodopa/carbidopa will continue to control symptoms. Selegiline is in a group of medications called monoamine oxidase type B (MAO-B) inhibitors