Cannabis and mental health

The cannabis plant is a member of the hemp family that has grown wild throughout the world for centuries.

Cannabis contains over 400 chemicals, and over 100 of these are cannabinoids. These are chemicals that affect ‘cannabinoid receptors’ throughout the body. They cause different physical and psychological effects.

Cannabis comes in two main forms:

• Herbal cannabis – This is made up of the dried leaves and flowering tops of the cannabis plant. It is also known as weed, grass, marijuana, spliff, skunk etc.
• Resin – This is a brown-black lump also known as ganja or hashish.

Cannabis can be taken in different ways including:

• smoking it on its own, in cigarettes or using a device called a ‘bong’
• eating or drinking it by adding cannabis to different foods or drinks
• vaping
• consuming cannabis oil.

People use cannabis for lots of reasons, including to relax and for fun.

There are preparations of cannabis which are licensed medicines in the UK. These are used to treat:

• some forms of childhood epilepsy
• spasms in multiple sclerosis (MS)
• uncontrollable nausea or vomiting.

Different kinds of cannabis have different strengths and produce different effects. The effects cannabis produces can vary from person to person. You usually won’t be able to tell how strong cannabis is or the kind of effects it will have on you until after you have taken it.

Cannabis is classified as a Class B drug under the Misuse of Drugs Act 1971.

The law says that if you are found with cannabis, you could receive a sentence of up to five years in prison. Often, individuals who are found to be using cannabis or have it on their person are cautioned or not prosecuted.

If you are found to be producing or supplying cannabis to other people, you could get up to 14 years in prison. You could also receive an unlimited fine.

Recreational cannabis use has been made legal in some countries, but not in the UK.

When you smoke cannabis, the chemicals in it reach your brain quickly through your bloodstream. The two most important chemicals in cannabis are:

• cannabidiol (CBD)
• tetrahydrocannabinol (THC)

THC is the only chemical in recreational cannabis that has been shown to have psychoactive effects. THC binds to certain receptors in the brain and gives you a ‘high’. Several studies have shown that when THC and CBD are inhaled together, CBD does not modify its effects in any way.

Different cannabis products will contain different amounts of CBD, THC and other chemicals.

The amount of THC in street cannabis (as opposed to medicinal cannabis) has increased substantially over the last 50 years. Cannabis that contains high levels of THC is more likely to cause negative effects in the people who take it.

When you use cannabis, you might experience different effects, such as:

• Feeling relaxed and talkative. Colours or music may seem more intense.
• Feeling sick, panicky and paranoid. You might hear voices, or feel depressed and unmotivated.

Often the unpleasant effects take longer to appear than the pleasant ones.

Studies suggest that cannabis can have harmful effects on physical and mental health.

Unfortunately, some people can become addicted to or dependent on cannabis. Studies show that cannabis is the third most commonly ‘misused’ substance in the world, after alcohol and tobacco.

If you are dependent on cannabis, you might do some of the following things:

• Use cannabis regularly.
• Struggle to stop using cannabis once you have started. For example, you might plan to only use it for half an hour, then spend the whole afternoon using it.
• Stop doing things you are supposed to do, or that you usually enjoy, because you are using cannabis instead.
• Spend a lot of time thinking about using cannabis.
• Find that your cannabis use is affecting your memory or concentration.
• Use cannabis even in situations where it might be dangerous. For example, when at work or when looking after children.
• Struggle to stop using it even if you feel like it’s having a negative effect on your life.

As previously stated, research shows that cannabis can have negative effects on your mental and physical health.

Psychosis

Research has shown that people who use cannabis have an increased risk of developing psychosis. This is where your thoughts and feelings change so dramatically that you lose contact with reality. People experiencing psychosis might experience delusions, hallucinations and disorganised thinking.

Research shows that the younger you are when you start using cannabis, the more likely you are to develop psychosis.

Using stronger forms of cannabis, or using it regularly, can also increase the risk of developing psychosis.

If you think you might be experiencing the symptoms of psychosis, you should speak to your GP straight away. The sooner you get help for psychosis, the better.

Other mental health problems

Using cannabis can also increase your risk of other mental health problems like:

• depression
• anxiety
• suicidal thoughts.

Research suggests that people who are already at risk of developing mental health problems might be at an increased risk of becoming unwell if they use cannabis regularly.

The younger you are when you start using cannabis, the more at risk of these problems you are. This is because your brain is still developing and can be more easily damaged by the chemicals in cannabis.

Some people use cannabis because they already have mental health problems and are trying to relax or take their mind off their symptoms. This might feel like it helps in the short-term, but there is evidence that if you already have mental health problems cannabis can make these worse.

If you are taking medication for a mental health problem, using cannabis won’t affect how that medication works. However, it might make you less likely to take your medication.

If you are experiencing mental health problems, speak to your GP to find out what treatments they might be able to offer you.

Physical health

Smoking cannabis can also affect your physical health, causing you to feel out of breath or giving you a cough. If you have asthma, smoking cannabis can make this worse. This is because inhaling smoke or water vapour, including cannabis and tobacco, is bad for your lungs.

Cannabis is often smoked with tobacco which carries the same health risks as smoking tobacco in cigarettes. There are also risks involved in smoking cannabis on its own.

Other areas of your life

If you are using cannabis often you might find that:

• it impacts your home, work or social life
• it affects your relationships with family and friends
• you stop doing activities that you used to enjoy
• if you use a lot of cannabis, it might also start to cost you a lot of money.

If you feel like cannabis is having a negative impact on your physical health, mental health or social life, help is available.

Reducing or stopping the use of cannabis can help reduce symptoms of mental health problems like depression and psychosis. However, you might need additional support for your mental health problems, and help to stop using cannabis safely.

If you are having physical health problems related to cannabis use, these might also improve when you have stopped using cannabis. However, if you are having ongoing problems, speak to your GP.

Withdrawal symptoms

People with cannabis dependence can struggle to stop using cannabis immediately. If you use cannabis frequently and stop using it, you might experience unpleasant withdrawal symptoms. The most common are:

• insomnia
• anxiety
• irritability and anger
• low mood
• restlessness
• decreased appetite.

You might also experience physical effects like:

• headaches
• sweating
• tremors
• chills
• abdominal pain
• fevers
• vivid dreams.

Withdrawal symptoms usually start within one or two days after cannabis was last used. They can last for around two weeks, and will probably be most intense during the first week. It can help to slowly reduce your use of cannabis over several weeks before stopping completely.

Synthetic cannabinoids are also known as:

• synthetic marijuana
• spice
• K2
• new psychoactive substances (NPS).

Synthetic cannabinoids are chemicals designed to have similar effects to cannabis. However, they are often a lot stronger and can cause serious mental and physical side-effects. In some cases, these can even be life threatening.

Synthetic cannabinoids are illegal. In the past, they were legal and known as one type of ‘legal high’. This is one of the reasons that people sometimes think they are safer than cannabis. However, they can be more dangerous than cannabis.

Research has shown that synthetic cannabinoids are associated with:

• delirium (a form of severe confusion and disorientation e.g. being unaware of where you are)
• agitation
• hallucinations
• violence
• self-harm.

Synthetic cannabinoids are also associated with some physical health harms including:

• heart problems
• kidney damage
• seizures.

There are lots of people who can help you decide whether you have a problem with natural or synthetic cannabis and support you with getting help.

Talk to someone you trust, like a friend or family member, if you feel like your cannabis use is getting out of control. They might be able to support you in speaking with a professional, if you feel that you need more support.

If you don’t feel comfortable speaking to someone you know, or talking to someone face-to-face, the drug advisory service FRANK has a confidential helpline open 24/7.

While you are working towards stopping using cannabis, or finding a support service, there are some things you can do to help yourself. These include:

• Keep a diary – Measure how much you are using and when. This can give you a better understanding of your cannabis use and how much it costs.
• Set limits – Use your diary to set limits on when and how much you use. This can be helpful if you are using cannabis all the time and find it difficult to imagine stopping completely.
• Explore your own values and goals – Think about what’s truly important in your life, who you want to be and what you want to do. Then think how your relationship with cannabis impacts on this.
• Avoiding bulk buying – Avoid buying cannabis when you have just been paid or given money. This can help you to avoid buying large amounts.
• Avoid people, places and activities that you associate with cannabis use – Be aware if you are going to be in an environment where you will be more likely to use cannabis. Or if you will be spending time with people who use it.
• Don’t use it if you are feeling sad or depressed – While this can be difficult, it can make you feel worse or mean that you get used to using cannabis when you are depressed.
• Seek mental health support – If you think you might have mental health problems like depression or anxiety, speak to your GP.
• Reward yourself – Give yourself treats for not using cannabis, like buying food you really like or going to the cinema.

Harm reduction

The most effective way to reduce the harm of smoking cannabis is to cut down or stop. However, there are some other things you can do to make the process less harmful or risky.

• Only smoke with trusted friends.
• Avoid smoking before work or school.
• Only buy cannabis from a trusted source.
• Use a little bit first and see how you feel.
• Avoid mixing cannabis with other drugs.
• Avoid smoking cannabis in public places.
• Avoid using cannabis before engaging in physical activity.

The charity Release offers a list of suggested harm reduction tips, which you can read on their website.

If your cannabis use is negatively affecting your mental or physical health, speak to your GP. Or, if you have one, speak to your mental health team.

You should not be denied mental or physical healthcare because you are using cannabis. However, the people treating you might encourage you to stop using cannabis or reduce your cannabis use if it might be contributing to your health problems.

Most people can safely reduce and stop cannabis either by themselves or with some support. If you are unable to do this, your doctor will be able to advise you on how to reduce your cannabis use safely and signpost you to local services.

If you smoke cannabis with tobacco, you might also need support to stop smoking. Your doctor can prescribe nicotine replacement therapy, like patches, chewing gum, tablets or vapes. You can find out more about support for stopping smoking on the NHS website.

If you are seeking help for your cannabis use, your doctor won’t report you to the police, unless you are putting others at risk.

If you are worried about a partner, friend or family member who is using cannabis, there are places you can get help, support and information:

• NHS, advice for families of drug users – This page includes lots of useful organisations that can help to support you.
• Families Anonymous – This organisation provides mutual support to families and friends of people who use drugs.
• Adfam – This charity tackles the effects of alcohol, drugs or gambling on family and friends in England and Wales.
• Scottish Families Affected by Alcohol & Drugs (SFAD) – This charity supports anyone concerned about someone else’s alcohol or drug use in Scotland.
• Drugfam – This charity supports people affected by another person’s harmful use of alcohol, drugs, substances or gambling.
• SMART Recovery, support group for friends and family – This charity provides a national network of mutual-aid meetings and online training programmes. This includes meetings for family and friends of someone with a substance use disorder.
• Release – A national centre providing advice and information to the public and professionals on drug use laws.

Here are some useful resources that can tell you more about cannabis and how to get support with stopping.

• Know cannabis – A website that can help you assess your cannabis use, its impact on your life and how to make changes if you want to.
• FRANK – Free confidential drugs information and advice.
  Helpline: 0300 123 6600
  Text: 82111
  Email
  

Further reading

Cannabis and you, workbook and self help tools (PDF) – This booklet from Drugs and Alcohol Northern Ireland can help you develop a plan for stopping or cutting down on cannabis use. It includes lots of useful information about cannabis.

This information was produced by the Royal College of Psychiatrists’ Public Engagement Editorial Board (PEEB). It reflects the best available evidence at the time of writing.

Expert authors: Dr Emily Finch and Dr Anto Eric Varughese

Expert by experience: Abiola Awojobi-Johnson

Full references for this resource are available on request.