High Prescribing: A Case Study of High-Potency Medicinal Cannabis Inducing Psychosis.

Introduction: There has been a recent significant increase in medical cannabis prescribing in Australia despite weak evidence for its effectiveness in treating the most common indications. Concern has been raised about the potential harms of inappropriate prescription of cannabis; however, there have been no prior published cases of psychosis secondary to medicinal cannabis in Australia. Case Presentation: We present a case of a 21-year-old Indigenous male with psychosis following switching from illicitly obtained cannabis to prescription cannabis, which resulted in Othello delusions towards his partner, violence towards her and ultimately an attempt to end his life. Discussion: Cannabis use is linked to the development of a psychotic illness whether it is prescribed or obtained illicitly. People who are prescribed cannabis are also at an elevated risk of developing cannabis use disorder (CUD). Cannabis prescribers need to screen for risk factors of drug-induced psychosis such as a family member with a psychotic illness, review patients regularly and provide harm minimisation advice to prevent damage from their prescription. Conclusion: There are clear dangers to overprescribing medicinal cannabis and the care that needs to be taken by prescribers to avoid them. There is a need for a change in the regulation of cannabis prescribing in Australia. Further research is warranted on the effects of the increase in prevalence of cannabis prescribing.