Background Mental health problems are common in people with substance misuse problems. However, there is a paucity of evidence regarding prescribing of psychotropic medications for people with comorbid mental health and substance misuse problems. Objective To explore the views of service users attending an addiction service on the appropriateness of psychotropic medications prescribed for their co-existing mental health problems. Setting A specialist addiction service in the North of England. Method A phenomenological approach was adopted. Semi-structured interviews were conducted with twelve service users. Data were analysed using thematic framework analysis. Main outcome measure Service users' views concerning the appropriateness of their prescribed psychotropic medications. Results The following themes captured service users' views on the appropriateness of their medications: benefits from medicines, entitlement to medicines, and assessment and review. Service users mostly described benefits from their medications (including those prescribed outside guideline recommendations) and there was also an awareness of the adverse effects they experienced from them. It appears that people with substance misuse problems have a particularly strong sense of their own needs and seek to influence prescribing decisions. Service users further described varied practices regarding assessment and review of their medications with evidence of regular reviews while others identified suboptimal or inadequate practices. Conclusion Most service users described improved functioning as a result of their prescribed psychotropic medications. Prescriptions that are inappropriate in terms of their usual indications may well be justified if they assist in stabilising service users and moving them on to recovery.