Dystonia is caused by incorrect signals from the brain to the affected body part but the causes for this are not yet fully understood.

Oromandibular dystonia, however, is sometimes caused by previous treatment for conditions including nausea, vertigo, anxiety, schizophrenia, and depression with medicines that work by blocking the chemical dopamine in the brain. Typically, this results in being affected in more than one place in the body. Another name for dystonia caused in this way is tardive dystonia.