Short answer
Cannabis use can cause psychosis. The DSM-5 includes cannabis-induced psychotic disorder as a diagnosis. Symptoms start during use or within days of stopping. Most episodes clear within weeks after the person stops using. Risk rises with THC content, with daily use, and with use that starts in the teen years.
Understanding Cannabis-Induced Mental Disorders
Symptoms
- Delusions, such as beliefs that others are watching or plotting.
- Hallucinations, most often hearing voices.
- Disorganized speech.
- Paranoia and fear.
- Confusion and trouble with memory.
These symptoms differ from ordinary intoxication. Intoxication peaks within minutes to hours and fades. Psychosis lasts days or longer and continues after THC leaves the body.
What raises the risk
- THC content. Studies label cannabis high potency at 10% THC or more. Average THC in US flower rose from about 4% in 1995 to about 15% in 2018.
- Frequency. Daily use carries more risk than weekly or monthly use.
- Age at first use. Use before age 25, while the brain is still developing, carries higher risk.
- Family history. A relative with schizophrenia or bipolar disorder raises risk.
- Concentrates and edibles. These deliver larger THC doses per session.
A 2015 case-control study in The Lancet Psychiatry found that daily use of high-potency cannabis accounted for 24% of first-episode psychosis cases in south London.
cannabis and psychosis symptoms
Does cannabis-induced psychosis become schizophrenia?
Sometimes. Follow-up studies report that about 1 in 3 people treated for cannabis-induced psychosis later receive a schizophrenia-spectrum diagnosis. People who stop using cannabis after the first episode have lower relapse rates than people who continue.
cannabis and psychosis symptoms
Does CBD help psychosis?
No CBD product is FDA-approved to treat psychosis or schizophrenia. Research is early. A 2012 trial in Translational Psychiatry tested CBD at 1,000 mg per day as an add-on to standard antipsychotic drugs in 42 people with schizophrenia. The CBD group showed lower levels of psychotic symptoms than the placebo group. The trial was small. That dose has not been replicated in a large study. CBD does not block THC-induced psychosis in real time.
When to get help
Get medical help if hallucinations, delusions, or confusion last more than a few hours after cannabis use. Call 911 if the person is a danger to themselves or others. Standard care starts with stopping cannabis. Short courses of antipsychotic drugs are common.
Limits of the evidence
Most studies are observational. They show a link between cannabis and psychosis, not proof that cannabis causes every case. People with a family history may be more likely to use cannabis and to develop psychosis. The dose-response pattern across studies supports a causal role for high-THC products.