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Cannabis and mental health
This factsheet explains how cannabis might affect your mental health and how to get help and support if you need it. This information is for people who are 18 and over in England.
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Frequently asked Q's
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- Cannabis is known by different names like marijuana and weed.
- Cannabis is a class B drug. This means it is illegal to have for yourself, give it away, or sell. But doctors can prescribe cannabis legally for limited medical reasons.
- Cannabis can have pleasant and bad effects.
- 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.
- Cannabis use can be a risk factor to the developing or the returning of mental illness symptoms.
- Research has found a link between cannabis and developing psychosis or schizophrenia.
- If cannabis is affecting your health or how you feel, you can see your GP.
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Cannabis is a class B drug. This means it is illegal to have for yourself, give away or sell.
It is made from the cannabis plant. It can be called many different names like marijuana, dope, grass, hash, herb, pot, and weed, and other things.
Stronger types of cannabis can be called things like skunk. See here under ‘Also called’ for more information.
You can smoke or eat cannabis, or drink it in a hot drink. You can find out more here
People use cannabis for different reasons, including enjoyment, peer pressure, and bonding with friends. Some people use it to relax or cope with stress. A small number of people use it to help with physical pain.
Younger people are more likely to use cannabis than older people. The highest amount of users are in the age group 15 to 24 years.
You can find more information about cannabis, on the FRANK website here
What are synthetic cannabinoids?
Synthetic cannabinoids used known as ‘legal highs.’ This is because they were legal. But most are now illiegal. This is because they are very strong and can have bad effects on your mental and physical health.
They are chemicals made to have similar effects to cannabis. Studies show they be dangerous and cause delirium, agitation, hallucinations, violence, and self-harm.
Can cannabis be prescribed for medical reasons?
Medical cannabis is a broad term for any sort of cannabis-based medicine used to relieve symptoms.
In the UK doctors can prescribe cannabis for medical reasons.
The NHS say:
- they only do this on rare occasions, for a small number of non-mental health conditions, and
- you would only be prescribed medical cannabis on the NHS if other treatments are not suitable or had not helped.
But you may be prescribed medical cannabis privately for some other conditions.
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When you take cannabis it goes into your bloodstream. The active compounds stick to a receptor in your brain. This causes chemicals to be released which make you experience effects. These can be enjoyable or bad.
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.
Stronger varieties of cannabis, like skunk, contain higher levels of THC.
CBD can lessen the unwanted psychoactive effects of THC. See What are the short term effects of cannabis? for more information about the effects of cannabis. This means that the effects of THC will be lower if there is more CBD in the drug.
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The short term effects of cannabis can be pleasant or bad. Cannabis effects people differently.
Most effects will usually last for a few hours and can depend on what form you take the drug in.
There can be long term effects. See Can cannabis affect my mental and physical health? for more information.
What are some of the pleasant short term effects of cannabis?
After taking cannabis some people can feel chilled out, happy, giggly and chatty, less anxious, relaxed, talkative.
Music and colours might seem clearer or stand out more.
What are some of the bad short term effects of cannabis?
After taking cannabis some people can feel:
- drowsy or sleepy
- paranoid or confused
- sick
- anxious
- lacking in motivation
- like it is hard to concentrate
- down or depressed
Cannabis can affect how you sense things. You may see, hear, or feel things that are not real. This is known as hallucinating.
You can read more about the effects of cannabis here
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You might become dependent on cannabis. If you use it regularly over a long time, you might need more and more to get the effect you want.
Some people who are dependent can get withdrawal effects if they do not take cannabis. The effects can be things like:
- sleeping problems
- sweating and shaking
- nightmares
- low mood
- upset stomach or diarrhoea
- finding it hard to concentrate
- feeling in a mood or irritable
- finding it hard to eat
- feeling sick
- cravings for cannabis
If you take cannabis with tobacco, you are at risk of being addicted to nicotine.
You can find more information on our following pages:
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Can cannabis affect my mental health?
The Royal College of Psychiatrists say:
- Cannabis use can increase the risk of things like depression and suicidal feelings.
- Your risk of developing psychosis increases the more you use cannabis and the stronger it is.
- Some studies say that that young cannabis users have an increased risk of developing psychosis.
- There is some evidence to show that cannabis use can make existing mental health symptoms worse.
- The younger you start using cannabis, you more at risk you are to developing mental health problems.
There is some evidence to show a link between the use of stronger cannabis and psychotic illnesses, including schizophrenia. But the link is not fully understood.
The national drug advisory service FRANK say using cannabis for some people can:
- Cause the return of symptoms for those who live psychotic illnesses like schizophrenia.
- Increase your chances of developing schizophrenia. Especially if mental illness runs in your family and you start using it in your teenage years.
- Make you depressed.
- Affect motivation.
- Affect memory.
- Cause mood swings.
Affect sleep. - Cause anxious or panicky feelings.
- Cause longer periods of of anxiety, paranoia or hallucinations.
You can find more information on our pages on:
- Depression
- Does mental illness run in families
- Psychosis
- Schizophrenia
- Suicidal thoughts – How to cope
Can cannabis affect my physical health?
The main bad effect on your physical health of taking cannabis is if you smoke it. With or without tobacco.
You can read more at the this link. See ‘The risks’ then ‘physical health risks’:
You can find more information on our page on Smoking and mental health.
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What can my GP do?
You can speak to your GP if cannabis use is affecting your physical or mental health.
It is best to honest with your GP about your cannabis use and symptoms. This will help your GP to offer you the right support.
The kind of support your GP might offer you is:
- support and treatment for your mental or physical health, or
- a referral to your local drug service.
You can find out more on our GP’s and your mental health page.
What about confidentiality?
You might be worried about telling your GP or other health professionals that you are using cannabis.
Health professionals must stick to confidentiality laws. This means that they will usually not be able to tell other people or services about what you have told them. Unless you agree.
You can find out more on our Confidentiality page.
What can my local drug service do?
Services usually offer things like talking therapy, support groups, and advice.
The talking therapy can help you understand why you use cannabis.
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.
You may be able to self-refer to this type of service. You can find local drug treatment support by clicking on this link.
If you cannot self-refer, speak to your GP, social worker, or health professional.
You can read more about what drug treatment is like here
Should I be referred to an NHS early intervention psychosis service?Your GP might suspect you are experiencing psychosis for the first time. They should refer you to an NHS early intervention psychosis service.
The service should see you within 2 weeks.
Can I be excluded from services?
You should not be excluded from:
- NHS mental health care because of cannabis use, or
- a substance misuse service because of a diagnosis of psychosis.
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.
See the Useful contacts section for contact details of useful organisations.
For more advice and information see our following pages:
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FRANK
Gives confidential advice to anyone concerned about using cannabis or other drugs.Phone helpline: 0300 123 6600
SMS: 82111
Email: through website
Live chat: through website.
Website: www.talktofrank.comMarijuana 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.Phone: 0300 124 0373
Email: helpline@marijuana-anonymous.org.uk
Website: www.marijuana-anonymous.org.ukNarcotics 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.Phone helpline: 0300 999 1212.
Website: www.ukna.orgAdfam
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.ukRelease
They give free non-judgmental, specialist advice and information to the public and professionals on issues related to drug use and drug laws.Phone helpline: 020 7324 2989
Address: 61 Mansell Street, London E1 8AN
Email: ask@release.org.uk
Website: www.release.org.ukWe 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/find-support/talk-to-a-trained-recovery-worker
Website: www.wearewithyou.org.ukChange 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.orgTurning 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
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© Rethink Mental Illness 2024
Last updated December 2024
Next update June 2026, subject to any changes