Cannabis use in psychosis patients is linked to antipsychotic treatment failure

Seven studies met inclusion criteria. Cannabis use was associated with increased odds of non-remission, prescription of more unique antipsychotic medications, cumulative clozapine prescription, and poor treatment trajectories. One study found lower past-year cannabis use in clozapine patients, and another found differences in chlorpromazine equivalent doses for olanzapine.

Systematic review of Ovid databases (Embase, MEDLINE, PsycINFO) for studies examining cannabis use and antipsychotic treatment failure in psychosis patients. Seven articles met eligibility.

Treatment failure in psychosis often leads to escalation through multiple medications, eventually reaching clozapine. If cannabis is a modifiable factor contributing to this progression, early cessation could prevent unnecessary treatment intensification.

The clinical pathway from first antipsychotic to clozapine represents increasingly difficult treatment. Cannabis use may be accelerating patients along this pathway, but the evidence base remains thin and methodologically limited.

Only seven studies met criteria, highlighting the paucity of research. Heterogeneous study designs and variable definitions of cannabis use and treatment failure. No prospective studies specifically designed to test this question.