Fact sheet 10
Cannabis and your mental health
Cannabis is the most common illicit drug used by young Australians.1 But there are many negative health effects linked to cannabis use, especially if you start using it when you are under 18 or use it regularly or over a long period of time. If you have a personal or family history of mental illness, cannabis use can trigger problems or make your symptoms worse.
Psychological effects of cannabis
Some people experience very unpleasant psychological effects when they use cannabis, like severe anxiety, paranoia or panic. Generally, people who start smoking cannabis when they are teenagers, and smoke heavily, are more likely to experience negative effects. Heavy or frequent use of cannabis may also lead to depression in later life, particularly for women.
In some cases, cannabis can also cause confusion, having beliefs that are not based on reality (delusions) or seeing or hearing things that are not there (hallucinations). This is called psychosis. Usually, it only lasts until the effects of the cannabis wear off and if the person isn’t used to the effects of cannabis or has consumed more than they are used to. Having said that, there is now evidence that cannabis use in adolescence is linked with an increased risk of developing schizophrenia later in life.
But some people have a greater risk of developing mental health problems than others. Cannabis use may trigger psychosis if, for example, you have a family history of mental illness/schizophrenia.
Cannabis can also make symptoms worse in people who already have depression or schizophrenia. A lot of people don’t realise that it can also increase anxiety. Some people attempt to deal with their depression or anxiety by smoking cannabis to ‘escape’. What they later discover is that their problems are made worse. If you have depression, cannabis may seem to help ease it before the effects of the drug wear off. But after that, using cannabis can make the depression worse. Cannabis can also reduce your chances of recovery from a psychotic episode.
The psychological effects of cannabis can have a ‘flow-on’ effect to other areas of your life, such as conflict at home or school/work, financial problems and memory problems, which also increase your risk of mental health problems. If you have a mental health problem, cannabis can cause other problems (for example with school work or relationships) that make dealing with your mental health problem harder.
Why cut out cannabis?
While most people use cannabis to relax or have fun, the negative psychological effects of cannabis can be unpleasant in the short term. For many people, there are also more serious effects in the longer term.
- If you are under 18, using cannabis regularly is more likely to lead to dependence, mental health problems and more general problems in life, like conflict at home or school/work.
- Your chances of having problems with cannabis are greater if you already have emotional problems, or problems at school, at home, or with the law.
- However old you are, cannabis use can cause bad psychological effects, like severe anxiety, paranoia or panic.
- If you have a family history of mental health problems, using cannabis makes you more likely to develop mental health problems yourself.
- If you already have a mental health problem like depression or schizophrenia, cannabis use is likely to make your symptoms worse, prolong episodes or cause you to relapse.
Tolerance and dependence
When people use cannabis regularly, they can develop a tolerance to it. This means they need to take more and more to get the same effect.
Heavy and frequent use of cannabis can cause physical dependence. Physical dependence occurs when a person’s body has adapted to a drug and is used to working with the drug present.
It’s also possible to become psychologically dependent on cannabis. This means that using cannabis becomes far more important than other activities in life. Some people crave the drug and find it very difficult to stop using it.
The chance of becoming dependent on cannabis is similar to the chance of becoming dependent on alcohol. Using cannabis when you are younger than 18 years of age makes it more likely that you will become tolerant to its effects or develop dependence. The more frequently you use cannabis, the greater the chance that you will become dependent. It also seems that young people can become dependent on cannabis using smaller amounts, and in a shorter time, than adults.
Managing your cannabis use
Deciding to do something about your cannabis use can be a big step and it may help to talk to someone you trust. This person could be a friend or family member or you may prefer to talk to a counsellor. Some counsellors specialise in drug and alcohol treatment but any counsellor should be able to offer you help. A counsellor can help you to work out how best to manage your drug intake. Counselling can either be done in a group or individually – your counsellor can help you work out which option is best for you.
If you have a mental health problem, it’s a good idea to talk to your doctor about your cannabis use, especially if you are taking any medications.
Drug and alcohol services and mental health services are available in most areas of Australia and each state has information available from an Alcohol and Drug Information Service phone line. The More Information and Support section below lists phone numbers and websites with useful advice and contacts.
Key points to remember
- If you’re at all concerned about your cannabis use, get help. Call the Cannabis Information and Helpline 1800 30 40 50 – for anonymous and non-judgmental support and advice, or call the Alcohol and Drug Information Service in your state (see below).
- Cannabis worsens the symptoms of existing mental health problems – if you have a mental health problem, it’s especially important that you get help to stop using cannabis.
- If cannabis use starts taking up more and more of your time, it’s a sign that you are relying on it rather than developing other aspects of your life. This places you at risk of becoming dependent.
- Being dependent on cannabis increases your chances of experiencing its negative physical and psychological effects.
- Cannabis use makes you more likely to develop a serious mental health problem, especially psychosis, in the long term.
More information and support
- Phone help lines and websites
- National Cannabis Prevention and Information Centre – www.ncpic.org.au
- Somazone – www.somazone.com.au
- Cannabis Information and Helpline – 1800 30 40 50
- Druginfo Clearinghouse – 1300 85 85 84
State-based Alcohol and Drug Information Services:
- ACT – (02) 6207 9977
- QLD – 1800 177 833
- NSW – 1800 422 599 or (02) 9361 8000
- NT – 1800 131 350
- SA – 1300 131 340 or (08) 8363 8618
- VIC – 1800 888 236
- TAS – 1800 811 994
- WA – 1800 198 024 or (08) 9442 5000
This fact sheet is based on information from:
-  NCPIC (2007) What’s the Deal? Cannabis Facts for Young People. Adelaide: Australian Network for Promotion, Prevention and Early Intervention for Mental Health (Auseinet).
- Mental Illness Fellowship of Victoria – www.mifellowship.org
- Australian Drug Foundation – www.adf.org.au
- beyondblue – www.beyondblue.org.au
- headspace – www.headspace.org.au
- ReachOut.com – www.reachout.com