Cannabis and drug-induced psychosis

Tamim and his friends smoked ganja on the roof every evening after university, for two years. Then Tamim began to hear his name whispered when no one was there, and became certain the CCTV in the building was following him. His friends laughed at first. Then they called his sister.

An illustration drawn from common experience. The person is invented; the pattern is not.

Understanding drug-induced psychosis

Cannabis, stimulants such as methamphetamine (yaba), and some other drugs can trigger psychosis: hallucinations, paranoia and confused thinking. In some people it settles when the drug stops. In others, especially those with a family history, it can reveal or bring forward a longer illness such as schizophrenia.

The finding worth knowing

A 2019 study across 11 sites in Europe and Brazil, published in The Lancet Psychiatry, found that people who used cannabis daily had about three times the odds of a psychotic disorder compared with people who had never used it, and about five times with daily high-potency cannabis.

Signs and symptoms of drug-induced psychosis

• Paranoia, hearing voices or strange beliefs after drug use
• Symptoms that continue after the drug has worn off
• Withdrawal from family, studies or work
• Increasing use despite frightening experiences

Treatment for drug-induced psychosis

Assessment covers both the psychosis and the substance use, and checks for other causes. Treatment usually includes antipsychotic medication for a period, support to stop using, and family involvement. Stopping the drug is an essential step for recovery and for preventing relapse.

What getting better can look like

Tamim’s way back might be months without ganja, a quieter mind, and a return to his course, with a sister who knows the early signs.

Common questions about drug-induced psychosis

Can ganja cause psychosis?

It is strongly linked to psychosis, and heavy daily use can bring it on. A 2019 study across 11 sites in Europe and Brazil found that people who used cannabis daily had about three times the odds of a psychotic disorder compared with people who had never used it, and about five times with daily high-potency cannabis. Stimulants such as yaba can also trigger psychosis.

Does drug-induced psychosis go away when you stop using?

In some people it settles once the drug stops. In others, especially those with a family history, it can reveal or bring forward a longer illness such as schizophrenia. Stopping the drug is an essential step, and treatment often includes antipsychotic medication for a period and support from family.

When to see a psychiatrist

If someone has become paranoid, is hearing voices, or is behaving strangely after drug use, please seek help promptly. If anyone is at risk of harm, call 999.

Care here is personal: built around your history, your health and what you want to change, and reviewed with you as it goes.

Sources

• Di Forti et al., The Lancet Psychiatry, 2019 (PMID 30902669)
• Schoeler et al., The Lancet Psychiatry, 2016 (PMID 26777297)