Cannabis and mental health
Cannabis is an illegal drug. This factsheet explains how it can affect your mental health and how to get help and support. This information is for adults in England who are affected by mental health issues. It’s also for their loved ones and carers and anyone interested in the subject.
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Overview
- Cannabis is known by different names such as marijuana and weed.
- Cannabis is an illegal drug that can make you feel happy or relaxed and anxious or paranoid.
- THC is the main chemical in cannabis which can change your mood and behaviour.
- Skunk is the most common name for stronger types of cannabis which has more THC.
- Research has found a link between cannabis and developing psychosis or schizophrenia.
- If cannabis is affecting your health or how you feel, you should see your GP.
Need more advice?
About
What is cannabis?
Cannabis is an illegal drug made from the cannabis plant. It can be called marijuana, dope, draw, ganja, grass, hash, herb, pot, and weed, and other things. Stronger types of cannabis can be called skunk.
You can smoke or eat cannabis. You can smoke it on its own or mix it with tobacco to make a ‘joint’ or ‘spliff’. It can also be cooked in food or brewed in tea.
People use cannabis for different reasons. Sometimes they use it to relieve mental or physical health symptoms. This is called self-medication. This may make you feel better in the short term. But in the longer term it can increase problems or create new ones.
Young people are more likely to use cannabis than older people.
You can find more information about cannabis, on the FRANK websites. You can find the details of the websites in the Useful Contacts section at the bottom of this page. The websites tell you what cannabis looks like, how it is used and the law on cannabis.
How does it work?
How does cannabis work?
Cannabis will go into your bloodstream when smoked. It will quickly be carried to your brain and stick to your receptors. Receptors are nerve endings in your body which respond to certain changes and stimuli. This will affect your mood and behaviour.
When eaten cannabis will still go into your bloodstream but will take longer. It will travel through your stomach and liver first.
Cannabis contains lots of different chemicals known as cannabinoids. Some examples are cannabidiol (CBD) and tetrahydrocannabinol (THC). THC is the main active ingredient in the cannabis plant. The more THC there is in cannabis, the greater the effect will be.
Skunk is a stronger variety of cannabis. It contains higher levels of THC.
CBD can lessen the unwanted psychoactive effects of THC such as hallucinations and paranoia. It can also reduce anxiety. This means that the effects of THC will be lower if there is more CBD in the plant.
How can it make me feel?
How can cannabis make me feel?
The effects of cannabis can be pleasant or unpleasant. Most symptoms will usually last for a few hours. The length of the effects can depend on what form you take the drug in. But there can be unpleasant long term symptoms. Especially if you use cannabis regularly over a long period of time. The risks can also be worse if are young and smoke strong cannabis, like skunk.
What are the pleasant effects of cannabis?
Cannabis can make you feel happy, relaxed, talkative or laugh more than usual.You may find that colours and music are brighter and sharper. Pleasant effects are known as a ‘high.’
What are the unpleasant effects of cannabis?
Cannabis can cause:
- hallucinations,
- changes in mood,
- memory loss,
- depersonalisation – feeling outside of your own body,
- paranoia,
- delusion and
- disorientation.
You might find it harder to concentrate or remember things. You may find it can cause your speech to become slurred. You may find that you can’t sleep well and you feel depressed. You may also feel hungry or feel like time is slowing down.
You might have lower motivation. And cannabis can affect how you sense things. You may see, hear or feel things differently. This is known as hallucinating. Hallucinations can be a sign of psychosis.
Psychosis can be a symptom of mental illness, including schizophrenia, schizoaffective disorder and bipolar disorder. These can be called ‘psychotic illnesses.’
For more information see our webpages on the following:
Is cannabis addictive?
Is cannabis addictive?
Cannabis can be addictive.
About 1 in 10 regular cannabis users become dependent on it. Your risk of getting addicted is higher if you start using it in your teens or use it every day.
You can develop a tolerance to cannabis if you use it regularly. This means you need more to get the same effect.
If you become addicted, you may feel withdrawal symptoms when you don’t use cannabis. For example, you might:
- be irritable,
- have cravings,
- have sleep problems,
- feel unmotivated,
- be unable to enjoy life,
- have a loss in appetite,
- have feelings of nausea,
- experience weight loss,
- be restless, and
- have mood swings.
You might smoke cannabis with tobacco. If you do you may become addicted to nicotine. This means you are at risk of getting diseases such as cancer and heart disease. So, if you stop using nicotine or cut down you could experience nicotine withdrawal too.
You can get information on stopping smoking tobacco by clicking the following link: www.nhs.uk/live-well/quit-smoking/take-steps-now-to-stop-smoking/
Cannabis and mental health
Can cannabis affect my mental health?
Regular cannabis use can be linked to an increased risk of anxiety and depression. But most research seems to have a focus on the link between psychosis and cannabis.
Using cannabis can increase the risk of developing psychotic illness, including schizophrenia. There is a lot of reliable evidence to show a link between the use of stronger cannabis and psychotic illnesses, including schizophrenia. But the link is not fully understood.
Cannabis can increase the chance of developing schizophrenia at an earlier age. This is due to the THC levels having an effect on schizophrenia.
Cannabis may be one of the causes of developing a mental illness, but it isn’t the only cause for many people. Not everyone who uses cannabis will develop psychosis or schizophrenia. And not everyone who has psychosis or schizophrenia has used cannabis. But you are more likely to develop a psychotic illness if you smoke cannabis. And you are ‘genetically vulnerable’ to mental health problems.
‘Genetically vulnerable’ means that you are naturally more likely to develop a mental health problem. For example, if people in your family have a mental illness, you may be more likely to develop a mental health problem. If someone in your family has depression or schizophrenia, you are at higher risk of getting these illnesses when you use cannabis.
Cannabis can have the following effects.
- Long term use can have a small but permanent effect on how well you think and concentrate.
- Smoking cannabis can cause a serious relapse if you have a psychotic illness.
- Regular cannabis use can lead to an increased risk of later developing mental illness. Especially if you use cannabis when you are young.
See our webpage on Does mental illness run in families for more information.
Psychosis and schizophrenia
What is the difference between psychosis and schizophrenia?
Psychosis and schizophrenia aren’t the same illness.
Psychosis is the name given to symptoms or experiences, which include hallucinations and delusions. Hallucinations make someone experience things differently to other people. This might be seeing things or hearing voices. Delusions are when people have unusual beliefs that other people don’t have.
Schizophrenia is a mental illness that affects how someone thinks or feels. Symptoms of schizophrenia include hallucinations and delusions. But often it will have other symptoms like feeling flat or emotionless, or withdrawing from other people.
For more information see our webpages on the following:
Getting help
How can I get help if cannabis is affecting my health?
Can I see my GP?
Speak to your GP if cannabis use is affecting your physical or mental health. Be honest with your GP about your cannabis use and symptoms. Your GP cannot offer you the right support if they don’t know the full picture.
Your GP might:
- offer you treatment at the practice, or
- refer you to your local drug service.
You can find local drug treatment support by clicking on the following link:
www.talktofrank.com/get-help/find-support-near-you
What can my local drug service do?
The service can offer counselling, support groups and advice. They can help you to:
- reduce your cannabis use,
- stop using cannabis,
- reduce the effect that cannabis has on your life, and
- support you to not start using again.
The service may be provided through the NHS or through a charity.
You may be able to self-refer to this type of service. If you can’t self-refer, speak to your GP or health professional.
Should I be referred to a specialist mental health service?
Your GP should refer you to a specialist mental health service if they think you have psychosis. The service could be the Community Mental Health Team or an Early Intervention Psychosis service.
Both psychosis and schizophrenia can be treated using antipsychotic medication and talking treatments.
For more information see our webpages on the following:
Can I be excluded from services?
You shouldn’t be excluded from:
- mental health care because of cannabis misuse, and
- a substance misuse service because of psychosis.
Can I see a therapist?
A therapist may be able to help you to understand the reason why you use drugs.
There are lots of different types of therapy. Cognitive Behavioural Therapy (CBT) is suggested as a treatment if:
- you misuse drugs, and
- have a common mental health problem such as depression or anxiety.
See our webpage on Talking therapies for more information.
Can I get further support?
You can:
- speak to a specialist drug service such as Frank, or
- join a support group such as Marijuana Anonymous UK.
Details of Frank and Marijuana Anonymous UK can be found at the end of the factsheet in the ‘Useful contacts’ section at the bottom of this page.
For more information see our webpages on the following:
Confidentiality
What about confidentiality?
You might be worried about telling your GP or other health professionals that you are using cannabis. But health professionals must stick to confidentiality laws. This means that they usually won’t be able to tell other people or services about what you have told them. Unless you agree.
They can only tell other people about what you have said if:
- there is a risk of serious harm to you or to others,
- there is a risk of a serious crime,
- you are mentally incapable of making your own decision, or
- the NHS share your information under ‘implied consent’.
For example, you might tell your doctor that you are planning to hurt yourself. Your doctor could decide to share this information with your healthcare or social care professionals. They should only do this to protect you and make sure you and others are safe.
See our webpage on Confidentiality of your information about your mental health for more information.
Useful Contacts
FRANK
Gives confidential advice to anyone concerned about using cannabis or other drugs.
Telephone helpline: 0300 123 6600. day
SMS: 82111
Email: through website
Live chat: through website.
Website: www.talktofrank.com
Marijuana Anonymous
They are run by people who have experience of cannabis use. They offer a 12-step recovery programme for people who want to quit cannabis use and are free to use.
Telephone: 0300 124 0373
Email: helpline@marijuana-anonymous.org.uk
Website: www.marijuana-anonymous.org.uk
DrugWise
Gives online information on a wide range of drug related topics. They do not have a helpline.
Website: www.drugwise.org.uk/
Narcotics Anonymous
They run online meetings and face to face meetings all over the country for people who want to stop using drugs. They offer sponsorship.
Telephone helpline: 0300 999 1212.
Website: www.ukna.org
Adfam
A national charity for families and friends of drug users. It offers support groups and confidential support and information.
Address: 27 Swinton Street, London, WC1X 9NW
Email: admin@adfam.org.uk
Website: www.adfam.org.uk
Release
They give free non-judgmental, specialist advice and information to the public and professionals on issues related to drug use and drug laws.
Telephone helpline: 020 7324 2989
Address: 61 Mansell Street, London E1 8AN
Email: ask@release.org.uk
Website: www.release.org.uk
We Are With You
A charity that supports people to make positive behavioural change. Such as a problem with alcohol, drugs, or mental health and wellbeing. They give support for families too. They have different services in different parts of the country.
Address: Part Lower Ground Floor, Gate House, 1-3 St. John's Square, London, England, EC1M 4DH
Online Chat: www.wearewithyou.org.uk/help-and-advice/advice-you/
Website: www.wearewithyou.org.uk/
Change Grow Live (CGL)
A charity that supports people to make positive behavioural change. Such as a problem with alcohol, drugs, or mental health and wellbeing. They give support for families too. They have different services in different parts of the country.
Webchat: via website
Website: www.changegrowlive.org/
Turning Point
Works with people affected by drug and alcohol misuse, mental health problems and learning disabilities.
Address: Standon House, 21 Mansell Street, London, E1 8AA
Email via online form: www.turning-point.co.uk/contact-us.html
Website: www.turning-point.co.uk
DNN Help
You can get free rehabilitation treatment through your local drug team. But you can pay for private treatment if you want to. This is an online treatment finder for private rehabilitation services.
Website: www.ddnhelp.com
© Rethink Mental Illness 2022
Last updated December 2022
Next update December 2025
Version number 4
You can access a fully referenced version of this information by downloading the PDF factsheet by using the link at the top of this page.
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