What is cannabis psychosis?

Cannabis psychosis is not one single diagnosis. The term is commonly used to describe psychotic symptoms that occur in relation to cannabis use.

That can include short-lived psychotic symptoms during cannabis intoxication, a more sustained psychotic episode following cannabis use, or cannabis use worsening an existing psychotic disorder.

Psychosis affects the way someone experiences and interprets reality. A person may hear or see things other people do not, develop beliefs that seem completely real to them but are not shared by those around them, become intensely suspicious or paranoid, or find it difficult to organise their thoughts and speech.

The fact that someone has used cannabis does not prove cannabis caused the psychosis. Equally, cannabis should not be dismissed simply because there may be other factors involved. Clinicians need to consider the timing and pattern of cannabis use, the symptoms, previous mental-health history, other drug or alcohol use and what happens after cannabis is stopped.

If cannabis use itself has become difficult to control but psychosis is not part of the picture, our guide to cannabis addiction covers dependence, withdrawal and the signs that use may have become a problem.

What are the symptoms of cannabis psychosis?

The symptoms are symptoms of psychosis. What raises the possibility of a cannabis-related episode is the relationship between those symptoms and cannabis use, particularly recent, frequent or high-potency use.

Symptoms can include

Hallucinations, such as hearing voices, seeing things or experiencing sensations that other people do not
Delusions, meaning strongly held beliefs that are not shared by others
Severe paranoia, including believing that people are watching, following, recording or trying to harm them
Disorganised thinking or speech, making conversation difficult to follow
Marked confusion or behaviour that is very different from usual
Agitation, fear or extreme anxiety
Withdrawal or reduced responsiveness
Significant disruption to sleep
Loss of insight, where the person cannot recognise that their experiences or behaviour have changed

What families may notice first

The person experiencing psychosis may not recognise that anything is wrong. Families and friends can therefore notice changes before the person does.

You may notice that someone has stopped sleeping, become frightened or suspicious of people they previously trusted, started talking about being watched or followed, begun hearing or seeing things other people cannot, or become increasingly difficult to follow in conversation.

Those observations are useful to a clinician. Rather than trying to diagnose the person yourself, describe exactly what has changed, when it began and what cannabis or other substances have been used.

How long does cannabis psychosis last?

There is no single reliable timeline.

Psychotic symptoms that occur during cannabis intoxication may settle as the immediate effects of the drug wear off. Other episodes persist beyond intoxication and require psychiatric assessment and treatment.

If hallucinations, delusions, severe paranoia, disorganised thinking or major behavioural changes persist, recur, or represent the person’s first experience of psychosis, it is important not to assume that waiting for the cannabis to leave the body will resolve the problem.

A clinician may need time and follow-up to understand whether the episode was primarily substance-induced, whether cannabis has triggered symptoms in someone already vulnerable to psychosis, or whether an independent psychotic disorder is emerging.

Can someone recover from cannabis psychosis?

Yes. People can recover from psychotic episodes associated with cannabis, but the course is different from person to person.

Stopping cannabis is important because continued use can make psychiatric symptoms and treatment more difficult to manage. For someone who has already experienced psychosis, returning to cannabis, particularly frequent or high-potency use, may increase the likelihood of further problems.

A cannabis-related first episode does not automatically mean that someone has schizophrenia. It does, however, deserve proper follow-up rather than being treated simply as a bad reaction to cannabis that can be forgotten once the immediate symptoms have settled.

Cannabis psychosis and schizophrenia: what is the difference?

This is one of the questions families ask most often after a first episode, and there is not always an immediate answer.

Psychosis is a description of a group of symptoms. Schizophrenia is one of several conditions in which psychosis can occur. Psychotic symptoms can also occur in bipolar disorder, severe depression, substance-related conditions and other medical or psychiatric situations.

Where symptoms appear in close relationship to cannabis use and resolve after the drug has stopped, clinicians may consider a substance-induced explanation. Where symptoms continue independently of cannabis, recur over time or are accompanied by other features of an enduring psychotic disorder, the diagnostic picture may be different.

Sometimes that distinction only becomes clear with time.

Research consistently finds an association between cannabis use and psychotic disorders, with stronger associations seen with frequent use and high-potency cannabis. That does not mean that everyone who uses cannabis will develop psychosis, or that cannabis is the only cause where psychosis occurs.

The practical point after any psychotic episode is simpler: cannabis use needs to be taken seriously as part of the psychiatric assessment and treatment plan.

Why can cannabis increase the risk of psychosis?

THC is the main intoxicating component of cannabis and is the cannabinoid most closely associated with psychotic effects. Cannabis with higher concentrations of THC can produce a more intense effect, and research has repeatedly found stronger associations between psychosis and frequent use of high-potency cannabis.

Risk is not the same for everybody. The amount and frequency of cannabis used, its potency, age and individual vulnerability can all form part of the picture.

A person’s response to cannabis can vary with factors including potency, frequency and amount of use, other substances being taken, their current mental state and their individual vulnerability. A previous history of psychosis should therefore change how future cannabis use is viewed.

What about Spice and synthetic cannabinoids?

Synthetic cannabinoids such as Spice are not the same drug as plant cannabis. They act on similar receptor systems but can produce much less predictable and sometimes severe psychiatric and physical reactions.

If someone develops psychotic symptoms after using a synthetic cannabinoid, tell the clinicians assessing them what was taken if you know. Do not assume that advice about ordinary cannabis applies in the same way.

Getting urgent help for cannabis psychosis

The right route depends on what is happening now.

Call 999 when there is immediate danger

Call 999 where there is a serious risk to life, someone may seriously harm themselves or somebody else, they are unresponsive, or their physical or mental state means they cannot be kept safe.

Call NHS 111 for urgent mental-health help in England

If someone needs urgent mental-health support but there is not an immediate risk to life, call 111 and select the mental health option.

NHS 111 can connect people of all ages, including concerned family members, with specialist mental-health support and advise on the appropriate next step.

When symptoms continue after the immediate effects of cannabis

If hallucinations, delusions, paranoia or disorganised thinking continue after the immediate intoxication has passed, or this appears to be a first episode of psychosis, seek medical assessment rather than continuing to watch and wait at home.

A GP can refer to specialist mental-health services. NICE recommends that people with a first episode or first presentation of psychosis have access to an Early Intervention in Psychosis service and are assessed without delay.

NHS treatment pathways for cannabis psychosis in England

Current or suspected psychosis needs mental-health assessment, even where cannabis or another substance may have contributed.

A first episode may involve an Early Intervention in Psychosis service. Someone who is acutely unwell may instead need support from a crisis service, psychiatric liaison team or inpatient mental-health service depending on the severity of the situation and whether they can be safely supported outside hospital.

Treatment can include psychiatric assessment, antipsychotic medication where clinically indicated, psychological treatment, family intervention and practical support with the disruption psychosis can cause to everyday life.

Substance use should be addressed as part of that care rather than treated as somebody else’s problem. NICE guidance is explicit that people should not be excluded from appropriate mental-health care because they misuse drugs or alcohol, and should not be excluded from substance-use treatment simply because they have psychosis.

The NHS Cannabis Clinic for Psychosis at South London and Maudsley

The Cannabis Clinic for Patients with Psychosis at South London and Maudsley NHS Foundation Trust was established in 2019 and is the first specialist NHS community service in the UK focused specifically on adults who have psychosis and want support to change their cannabis use.

The clinic uses a dual-diagnosis approach, bringing work on cannabis use into the person’s existing psychiatric care. It has been commissioned by SLaM since 2022.

It is not a national referral service. Current eligibility requires the person to be aged 18 or over, have a diagnosis of psychosis and already be open to a SLaM service.

An early proof-of-concept evaluation looked at 46 people who completed the clinic’s intervention and reported substantial reductions in cannabis use alongside improvements in clinical and functional measures. Because this was a small, uncontrolled service evaluation, the results are encouraging rather than proof that the intervention alone caused those improvements.

The wider principle is important: where psychosis and problematic cannabis use occur together, both need to be recognised and treated. Our dual diagnosis treatment page explains how Abbington House approaches addiction alongside co-occurring mental-health difficulties once someone is clinically suitable for residential addiction treatment.

For families: supporting someone with cannabis psychosis

Often the person searching for this information is not the person experiencing the symptoms.

It may be a parent who has watched their son or daughter become increasingly frightened and suspicious. A partner whose conversations keep returning to who is watching the house. A family member trying to work out whether what they are seeing is cannabis intoxication, a bad reaction or something that needs psychiatric help.

You do not need to settle that question yourself.

What families can do

Describe what you can observe. “He has not slept properly for four nights and believes the neighbours are recording him” gives a clinician more useful information than trying to supply a diagnosis.
Include the substance-use history. Explain what cannabis or other drugs you believe have been used, how often, and whether the pattern has recently changed.
Seek help even if the person disagrees. Loss of insight can be part of psychosis. A concerned family member can call NHS 111 or contact the person’s GP to explain what they are seeing.
Call 999 where there is immediate danger. Do not wait for someone to agree that they need help if there is a serious risk to life or safety.
Keep the interaction calm. You do not have to prove that a frightening belief is wrong. Focus on the person’s distress, immediate safety and getting professional help.
Write down important changes. Dates, changes in sleep, behaviour and substance use can be helpful when symptoms have developed over several days or weeks.

What families cannot do

You cannot argue someone back into insight, make a psychiatric diagnosis or provide the treatment that a psychotic episode may require.

What you can do is notice what has changed, communicate it clearly to professionals, help the person remain connected with care and continue to be present once the immediate crisis has passed.

Family involvement can remain important later if addiction treatment becomes part of the recovery plan. Abbington House provides family support alongside residential treatment to help the people closest to someone understand addiction, recovery and what may be helpful when the person returns home.

Where private residential treatment may fit

Private residential rehab is not first-line treatment for someone who is currently experiencing acute psychosis.

If someone is actively hallucinating, severely paranoid, acutely disorganised, unsafe or in the early assessment and treatment of a first psychotic episode, the priority is appropriate psychiatric care.

Residential addiction treatment becomes a different question later.

It may become relevant when the acute episode has settled, the person is clinically stable, cannabis dependence or repeated cannabis use remains a significant problem, and structured addiction treatment can safely sit alongside any ongoing psychiatric care.

Residential addiction treatment may be considered where

the acute psychotic episode has resolved and the person is currently stable
cannabis use has become difficult to control
attempts to stop at home repeatedly have not lasted
the home or social environment is closely connected to continued cannabis use
the person understands that returning to cannabis may place their mental health at further risk
existing psychiatric treatment can safely continue alongside addiction treatment
an assessment concludes that a residential addiction setting is appropriate

Abbington House may not be the right setting where

someone is currently experiencing an active psychotic episode
they need acute psychiatric assessment or admission
their level of risk requires a psychiatric hospital setting
their psychiatric needs cannot safely be managed alongside a residential addiction stay

Not every person with cannabis dependence needs residential treatment, and not everybody with a history of cannabis-related psychosis will be suitable for admission.

Our Getting Help section explains the wider NHS, community, outpatient and private treatment routes. If residential treatment is specifically what you are considering, our cannabis rehab page explains what treatment at Abbington House involves.

Where Abbington House may fit after cannabis psychosis

Abbington House is a CQC-regulated private residential drug and alcohol rehab centre in Stevenage, Hertfordshire.

Abbington House does not provide acute psychiatric treatment for active psychosis.

Where psychotic symptoms have settled, the person is clinically stable and cannabis dependence remains a problem, residential treatment can focus on the substance-use side of the picture: understanding why cannabis became difficult to stop, identifying the situations that lead back to use, working with cravings and developing ways of managing life without returning to cannabis.

Where someone is already receiving psychiatric or community mental-health care, that existing treatment needs to be considered during the admission assessment. A residential stay should not disrupt psychiatric care that the person needs in order to remain well.

Treatment at Abbington House includes individual and group therapy, family support, relapse-prevention work and planning for the return home, followed by a year of aftercare.

If our assessment indicates that Abbington House is not an appropriate setting because psychiatric care needs to come first, we will say so.

Common questions about cannabis psychosis

Can cannabis really cause psychosis, or does it only trigger something already there?

There is no single answer that applies to everybody. Cannabis can produce psychotic symptoms during intoxication, and cannabis use is also associated with a higher risk of psychotic disorder, particularly with frequent and high-potency use.

In an individual person, however, it may not be possible immediately to separate the effect of cannabis from an underlying vulnerability or emerging psychiatric condition. That is a clinical assessment rather than something that can be established from cannabis use alone.

Will stopping cannabis make the psychosis go away?

Some psychotic symptoms associated with intoxication settle after cannabis is stopped. More sustained or severe episodes may require psychiatric treatment and follow-up even after cannabis use has ended.

Stopping cannabis is still important, but it should not be used as a substitute for psychiatric assessment where symptoms are significant, persistent or recurring.

Can cannabis psychosis turn into schizophrenia?

A cannabis-related psychotic episode does not mean someone has schizophrenia. However, some people who initially present with substance-induced psychosis later develop a longer-term psychotic disorder.

That is one reason a first episode should receive proper psychiatric assessment and follow-up, even if the symptoms improve after cannabis is stopped.

Is high-potency cannabis more likely to cause psychosis?

Research has found a stronger association between psychotic disorder and frequent use of cannabis with a high THC concentration. Risk is particularly associated with patterns such as daily or near-daily high-potency use.

That does not mean a lower-potency product is risk-free, particularly for someone who has already experienced psychotic symptoms.

Is CBD safe if someone has experienced psychosis?

CBD is different from THC, but products sold as CBD can vary considerably in their contents and may contain some THC.

Someone who has experienced psychosis should not use cannabis or cannabinoid products to self-treat psychiatric symptoms without discussing this with the clinician responsible for their mental-health care.

What about synthetic cannabinoids such as Spice?

Synthetic cannabinoids are different drugs from plant cannabis and can produce severe and unpredictable psychiatric and physical effects.

If psychotic symptoms follow the use of Spice or another synthetic cannabinoid, tell the healthcare professional assessing the person what was taken if that information is available.

Does someone with cannabis psychosis have to go to hospital?

Not necessarily. Some people can be assessed and treated safely in the community through specialist mental-health services.

Hospital admission may be needed where symptoms are severe, safety cannot be maintained outside hospital, or closer psychiatric assessment and treatment are required. That decision is based on the person’s clinical presentation and risk rather than on cannabis use alone.

Can someone be sectioned because of cannabis psychosis?

Psychosis can sometimes lead to compulsory assessment or treatment under the Mental Health Act where the legal criteria are met. Cannabis use by itself is not the reason for detention.

Decisions about compulsory assessment or treatment are made by authorised professionals according to mental-health law and the person’s circumstances. Changes made by the Mental Health Act 2025 are being introduced in stages, so current information about rights and detention should be checked through the NHS Mental Health Act guidance.

Does cannabis psychosis go on your medical record?

If someone is assessed or treated by a healthcare service for psychotic symptoms, relevant information about that assessment and treatment would normally form part of their medical record.

Medical records are confidential and access to them is governed by healthcare confidentiality and data-protection requirements.

Getting help

If this may be someone’s first episode of psychosis, or symptoms are continuing after cannabis use has stopped, the appropriate route is medical and psychiatric assessment. A GP or urgent mental-health service can help connect the person with specialist care, including an Early Intervention in Psychosis service where indicated.

If the psychotic episode has already been treated and settled, and the remaining question is how to stop cannabis use, there are several possible routes. Our Getting Help section explains community, NHS, outpatient and private treatment options.

If private residential treatment is being considered, our cannabis rehab page explains how treatment works at Abbington House and when a residential stay may make sense.

If you need to discuss whether someone with a previous history of psychosis could be suitable for Abbington House, speak to our admissions team. Suitability is assessed before admission, and we will tell you where psychiatric care needs to take priority.

Call 01438 583222 or request a confidential callback.

Clinical information and sources

This page has been written to explain cannabis-related psychosis and where addiction treatment may fit. It does not replace individual psychiatric assessment.

Cannabis Psychosis

About The Author

Michael Williams