A woman with schizophrenia in methadone treatment was admitted for treatment of psychotic symptoms and cocaine addiction. Her prescribed medication was a 400 mg daily dose of methadone. It became evident during her hospitalisation that she was only taking a small part of the medication herself and she sold the rest of the methadone to finance her addiction of cocaine. To address this kind of misuse of prescribed medication, this paper examines the importance of following guidelines put forward by the NBH (National Board of Health).