Marijuana (cannabis)

Marijuana, dried leaves and flowers of the cannabis plant, is the most common and least powerful form of cannabis. Marijuana looks like chopped grass, and ranges in colour from grey-green to greenish-brown. Marijuana is smoked in hand-rolled cigarettes (joints) or in a pipe (bong).

Cannabis is a drug that derives from Indian hemp plants such as Cannabis sativa and Cannabis indica.

There are three main forms of cannabis:

  • Marijuana
  • Hashish (hash) is dried cannabis resin which comes in small blocks ranging in colour from light brown to nearly black. The concentration of THC in hashish is high and produces strong effects. Hash is added to tobacco and smoked, or baked and eaten in foods such as "hash cookies".
  • Hash oil is a thick, oily liquid, golden-brown to black, that can be extracted from hashish and is the most potent form of cannabis. This form is rarely found in Australia.

The cannabis plant contains approximately 460 known compounds. Sixty of these are unique to the cannabis plant and are called cannabinoids.  The cannabinoid that is mainly responsible for the psycho-active effects of cannabis is delta-9-tetrahydrocannabinol or D-9 THC .

The brain cells of humans have special receptors to which bind the body's own, naturally produced cannabinoids (e.g. Anandamide), which act much like plant-derived cannabinoids. While research is still being done in this area, the body's own cannabinoids are thought to be involved in a range of functions including thinking, memory, and mood states; control of appetite; pain relief; physical activity; blood pressure; and inflammatory and immune responses.

Plant derived THC binds to brain cells' cannabinoid receptors and has been shown to release an important brain chemical messenger called dopamine which is responsible for feelings of pleasure or reward. Dopamine is also released by a range of other drugs such as heroin, nicotine, and speed, all of which can produce dependence in regular users.

Who uses cannabis?

Cannabis is the most widely used illicit drug in Australia. More than one third of all Australians have used cannabis at some time in their lives, and about one third of these people have used cannabis in the last year. Nearly one in five people aged 20-29 report recent use.

What problems can arise?

Many people can use cannabis from time to time without experiencing serious problems, but some people do run into trouble along the way, particularly those who use heavily or regularly, and those who have mental health problems.

If you are a regular user, you might have trouble controlling your use of cannabis, lack motivation, have decreased energy, and/or have problems with concentration, your memory, and your attention span.

If you mix cannabis with tobacco, which is common in Australia, your risk of lung disease is significantly increased.

Other problems can involve:

  • Study - missing lectures, difficulty concentrating, forgetfulness, lack of motivation. 
  • Relationships - conflict with family, friends, partners.
  • Work - difficulty concentrating, lack of motivation.  
  • Physical and mental health- respiratory problems, some cancers, depression and anxiety. Cannabis is a particularly risky for people who already have a mental health problem.
  • Driving - driving under the influence of cannabis impairs judgment and ability, and road-side testing for cannabis is now available in most states and territories in Australia.
  • Money worries - cannabis is expensive.
  • Legal issues - cultivation, use, possession, and sale of cannabis are generally prohibited in Australia (see "Where to find more information" for links to sites with detailed information about legal issues).
  • Dependence - about one person in ten who has ever tried cannabis might become dependent at some time. People who use heavily on most days are at risk of having withdrawal symptoms when they stop using cannabis such as anxiety, restlessness, depression, irritability, reduced appetite, sleep disturbance and possibly aggressive behaviour. Those who mix cannabis with tobacco often develop a dependence on both drugs.

Am I dependent on cannabis?

If you haven't already taken the cannabis use self-assessment, spare 5 minutes to take it now. If your score is 27 or over, you might be dependent on cannabis.

Generally speaking, if you answer YES to a few of the following you could be dependent on cannabis:

  • I can't control my cannabis use or use/smoke more than I mean to
  • I need to smoke more and more to get the same effect
  • I skip uni, work, or other important things because of being stoned or feeling the after effects
  • I'm worried about my cannabis use and I want to cut down or stop
  • I've tried to stop but can't
  • I have problems in other areas of my life because of cannabis (legal, social, financial etc)
  • I have withdrawal symptoms when I stop

What treatments are useful for cannabis problems?

There are a number of cannabis treatment options available in Australia. Some options include counselling, withdrawal (detoxification) and medication. Most programs adopt strategies that have an overall aim of reducing the harms and risks related to a person's drug use. Some self-help strategies can be very useful, and the cannabis self-help materials on this site offers practical tips for self-management.

Psychological therapies

Counselling that's based on Cognitive Behaviour Therapy or CBT is effective in helping people to deal with a range of problems associated with cannabis use. CBT is a short-term, talking therapy that targets unhelpful patterns of thinking as well as behaviours that lead to or increase cannabis use. CBT also helps people to cope with problems more easily so they feel more optimistic about their ability to control cannabis use. 


As yet there are no medications routinely prescribed for cannabis dependence or withdrawal, although some do show promise and are currently being trialled in Australia and elsewhere. Medication can be prescribed to help with the symptoms of cannabis withdrawal but it is best to consult with a health professional about what might be suited to you.

Source of information: DrugInfo Clearinghouse - Australian Drug Foundation

Information page about cannabis by the Australian Drug Foundation - Drug Info Clearinghouse

The Australian Drug Foundation is a national service aimed at helping to prevent alcohol and other drug problems, and reduce alcohol and other drug harms in the community. The ADF's information page provides details on the effects, withdrawal and treatment options of cannabis.

Cannabis fact sheet by UnitingCare ReGen

UnitingCare ReGen is an alcohol and other drug treatment and education agency based in Melbourne. They have produced a general information fact sheet on cannabis.

Marijuana fact sheet by Headspace

Youth friendly, community based health service for young people 12 - 25 and their families. Headspace offers young people help for a range of issues including health, education, work, mental health and drug and alcohol use. Headspace's fact sheet on cannabis (and marijuana) has some useful information such as it's effects on physical and mental health.

Marijuana/cannabis fact sheet produced by Reach Out!

Reach Out! is an initiative of the Inspire Foundation. The aim of the service is to improve young people's mental health and well being by providing support information and referrals. Reach Out's fact sheet has information on effects, risks and treatment options.

It may be a big step for your friend to get help for cannabis use. Speaking to a professional yourself might help you become better informed about the effects of cannabis and what someone might go through in withdrawal. If you are wanting to know more about managing cannabis use you may want to get in touch with the National Cannabis Information and Prevention Centre (NCPIC) 1800 30 40 50 or visit their website using the link below. 

Family and friends infomation by the National Cannabis Prevention and Information Centre (NCPIC)

The NCPIC's website provides cannabis information to the community, users, their families and the various workforces involved in the delivery of cannabis related interventions.  A link to their page provides information to family and friends of cannabis users. 

DrugInfo Clearinghouse - Australian Drug Foundation

DrugInfo Clearinghouse is a service provided by the Australian Drug Foundation. It functions as a drug prevention network providing information about alcohol, other drugs, and drug prevention.


A community based service for people aged 12 - 25 and their families, Headspace provides help for issues including health, education, work, mental health and drug & alcohol use.

National Cannabis Prevention and Information Centre (NCPIC)

The NCPIC mission is to reduce the use of cannabis in Australia by preventing uptake and providing the community with evidence-based information and interventions.

National Drug and Alcohol Research Centre (NDARC)

NDARC conducts research and related activities that increases the effectiveness of Australian and international treatment and intervention responses to alcohol and other drug related harm.

Reach Out!

An initiative of the Inspire Foundation, Reach Out! is a web based service that provides information, support and interactive features to help young people get through tough times.

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