Medications approved by the FDA for the treatment of alcohol and opioid dependence, including acamprosate, disulfiram, naltrexone, methadone, and buprenorphine , have not been widely studied in the dual diagnosis population. Often, study participation criteria exclude people with concurrent substance use disorders and mental illness, and only in recent years has research specifically focused on this population become more common. Pharmacotherapy has also been underutilized in practice. A survey of 955 people with bipolar disorder found that although 8% met criteria for current alcohol use disorder and 5% met criteria for current nonalcoholic substance use disorder, only 0.4% were receiving disulfiram, methadone, naltrexone and/or buprenorphine (Simon et al., 2004). The high prevalence of co-occurring substance abuse and mental illness, as well as the challenges associated with treatment, mean that underutilization and lack of research are likely to critically impact client outcomes. This article explores the evidence for the safety and effectiveness of pharmacotherapy for drug addiction. disorders in clients with comorbid mental illness. It has been hypothesized that the use of such medications carries risks unique to this client group and that pharmacotherapy nevertheless plays a role in the treatment of substance dependence in these clients. The MNCat and Google Scholar search databases were searched for publications addressing the use of FDA-approved medications for alcohol and opioid dependence in clients with comorbid psychiatric diagnoses. Large-scale, double-blind, controlled studies were prioritized. Where this information was not available, theoretical articles, literature reviews and case studies were included. The article finds that research on ...... middle of article ...... questions. These beneficial effects were not anticipated. Specifically, symptoms of psychosis spectrum disorders and PTSD appear to be improved by a number of pharmacotherapeutic options. Above all, more research is needed. The large gaps in our current understanding of these drugs are evident, but there is also scope to examine further evidence in this area. Other exams would benefit from a wider range of topics. First, the theoretical and neurological understandings of psychiatric disorders and pharmaceuticals discussed in this article could be explored to add context to case studies when larger research studies are not available. Second, the effect of psychiatric medications on substance use would be useful to prescribing clinicians. Third, further reviews of the literature would benefit from the inclusion of pharmacotherapy for nicotine dependence..