Cannabis-induced psychosis: paranoia, hallucinations and the link with schizophrenia

Can weed cause psychosis?

Yes. Cannabis-induced psychosis happens in some people who use cannabis (known in Egypt as hashish, or bango), and it is a state in which it becomes hard to tell what is real from what is not. The UK's National Health Service (NHS) lists cannabis among the drugs known to trigger psychotic episodes, and notes that an episode can also happen when someone suddenly stops drinking alcohol or taking drugs after using them for a long time. The US National Institute on Drug Abuse (NIDA) explains that such an episode can be temporary, and that it is more likely at high doses.

The same picture, sometimes in a more severe form, appears with synthetic cannabinoids, known in Egypt as strox and voodoo. According to a scientific review published in 2019, these substances seem to have stronger effects on the body and mind than cannabis, and they can trigger a new psychosis or bring back symptoms that had been stable. You can read more in our article on strox and voodoo.

What does cannabis-induced psychosis look like?

The US National Institute of Mental Health (NIMH) describes psychosis as a set of symptoms in which a person loses some contact with reality. Families may notice signs such as:

• Intense suspicion (paranoia): believing that someone is watching, following or plotting against them, that their phone is being monitored, or that their food has been poisoned.
• Hallucinations: hearing voices or seeing things that other people don't.
• Delusions: fixed false beliefs that don't change with discussion, such as having special powers or believing that messages on television are aimed at them.
• Confused or hard-to-follow speech, and behavior that doesn't fit the situation.
• Fear, anxiety and panic, sometimes with intense tension or aggression when they feel threatened.
• Disturbed sleep and withdrawal from people, neglecting personal hygiene, and slipping at school or work.

NIDA notes that anxiety, fear, distrust of others and hallucinations are more common when the product is strong, the amount is large, or the person has little experience with cannabis. Remember that a diagnosis is made by a doctor, because similar symptoms can come from other causes.

How long does cannabis psychosis last, and what keeps it going?

There is no fixed duration for everyone. According to the same 2019 review, diagnostic criteria use about a month of complete abstinence as a reference point for diagnosing a substance-induced (drug-induced) psychosis, not as a set recovery date, and whether symptoms are still present during a long period without the substance is often what shows whether there is a separate psychotic disorder that needs ongoing treatment. The review also points to studies finding that symptoms can last much longer in some people. That is why the duration can only be judged properly through follow-up with a doctor.

The main things that make an episode last longer or come back are:

• Carrying on using: an analysis of 24 studies published in The Lancet Psychiatry in 2016 found that people who kept using cannabis after psychosis began had more relapses than those who stopped, and longer hospital stays than people who did not use it.
• Strong products and daily use, both of which are linked to a higher risk of psychotic disorder, as in the European study described below.
• An underlying tendency toward a longer-lasting psychotic disorder: the episode may be the start of an illness such as schizophrenia rather than just a temporary effect of the substance.
• Delaying treatment: NIMH stresses that starting treatment early is linked to better outcomes.

Cannabis and schizophrenia risk: what does the research say, carefully?

The link between cannabis and schizophrenia is real and strong, but scientists are still studying how far cannabis is a direct cause, because genes, trauma and stress affect both drug use and mental health, as NIDA explains. These are the key findings:

• A meta-analysis of 50 studies published in Schizophrenia Bulletin in 2020 found that about 34% of people who had a cannabis-induced psychosis were later diagnosed with schizophrenia, the highest rate among the substances studied.
• A European multicenter study published in The Lancet Psychiatry in 2019 found that daily use was linked to roughly three times the likelihood of a psychotic disorder compared with people who had never used cannabis, and roughly five times with daily use of high-potency types.
• NIDA notes that the link between heavy cannabis use and schizophrenia appears especially strong in young men compared with women.

This means a psychotic episode after cannabis is not a passing event you can ignore, but it also does not mean schizophrenia is inevitable: most of the people in the analysis above were not later diagnosed with schizophrenia, and stopping early and getting treatment improve the outlook. To understand schizophrenia itself, read our guide to schizophrenia.

Who is most at risk of cannabis-induced psychosis?

• Young people: the US Centers for Disease Control and Prevention (CDC) says the link between cannabis and schizophrenia is stronger in people who start using at an earlier age.
• Frequent or daily use: the more often someone uses, the higher the risk, according to the same source.
• Strong products: NIDA reports that the concentration of the active ingredient (THC) in cannabis seized in the United States rose from about 4% in 1995 to about 16% in 2022, and synthetic cannabinoids have even stronger effects.
• Family history: in people with an inherited vulnerability to psychotic disorders, use is linked to psychosis starting at a younger age, according to the same institute.
• People who have had psychosis or another mental health condition before, since use can make their symptoms worse.

If you are also wondering about dependence itself, our article is hashish addictive? may help.

How should the family respond during an episode?

Seeing your son or husband frightened and convinced that everyone is against him can be terrifying. These steps help calm the situation:

1. Stay calm: speak in a low voice and short sentences, and cut down the noise and the number of people in the room.
2. Don't argue with his beliefs: trying to convince him that the suspicion is untrue can make him more afraid. Acknowledge his feelings rather than the content of his thoughts, for example: "I can see you're scared, and I'm here with you."
3. Don't blame or threaten him now: the time to talk about drug use comes after he has calmed down.
4. Move dangerous objects out of his reach if you can do so safely, and don't leave him alone if he is severely agitated.
5. Protect yourself first: if he becomes aggressive, move to a safe place and call the emergency numbers in the box below straight away.
6. Contact a psychiatrist as soon as possible, even if the episode has passed, because follow-up is part of stopping it from coming back.

When should you get specialist help?

Don't wait for a second episode. Book an assessment with a psychiatrist if:

• Suspicion, hallucinations or strange talk have appeared even once after cannabis or strox
• Symptoms lasted more than a few days after stopping, or come back every time he uses
• You notice withdrawal, self-neglect and slipping at school or work
• He can't stop using despite what is happening to him
• There is a family history of schizophrenia or bipolar disorder

If the person refuses to come, the family can come alone first to understand the situation and learn what steps are possible. You can also call the hotline of Egypt's Fund for Drug Control and Treatment of Addiction on 16023 for confidential treatment at no cost through its partner centers.

Drug-induced psychosis treatment: how does it work?

1. Stopping the substance completely: this is the foundation, and the 2019 review stresses the importance of removing cannabis and any other substance that may be contributing to the symptoms, even if it is hard at first. But if he also uses alcohol, sedative pills, pregabalin (Lyrica) or tramadol, he should not stop them suddenly on his own at home, because withdrawal from them can be dangerous and can even trigger a psychotic episode, as the NHS notes, so stopping should happen under medical supervision.
2. A full psychiatric and medical assessment: to rule out other causes and find out whether the psychosis is linked to the substance alone or to a separate illness. This can start with an appointment with a psychiatrist, available to men and women aged 15 and over (under 18 with a parent or guardian's consent).
3. Medication when needed: the NHS says antipsychotics are usually the first treatment for psychosis, and they can take days or weeks to work. Only the doctor decides whether someone needs them and when to stop them, and no medicine should be stopped suddenly without speaking to the treating doctor.
4. Inpatient care when it is severe: if the symptoms are severe or the risk is high, the person may need inpatient psychiatric treatment, which at Oxygen Center is for males only, aged 15 and over.
5. Psychological therapy, family support and follow-up: such as cognitive behavioral therapy and family sessions, which the NHS mentions, with regular follow-up to prevent relapse.

Why must addiction and mental health be treated together?

Treating the psychosis alone while drug use continues is like putting out a fire while leaving its source burning, and treating the addiction alone can leave mental health symptoms that push someone back to using. That is why NIDA stresses that integrated treatment, which deals with both conditions at the same time, leads to better health outcomes. Learn more about this idea in our article on dual diagnosis. And the reassuring news, as NIMH notes, is that recovery from psychosis is possible with early diagnosis and the right treatment.