With legalization underway, it is increasingly common for marijuana to be available to patients. While few longitudinal or causal studies have been conducted – it is clear that those with schizophrenia are at the highest risk with use. Marijuana can both worsen or trigger symptoms of psychosis and should be avoided. Some types of marijuana may increase the risk, or at least speed up the onset, of first episode psychosis and schizophrenia onset.
There is also evidence that it can worsen mood in depression and increase risk of mania in bipolar disorder. Those with schizophrenia are the at highest risk of negative outcomes with use.