Person rolling joint, close-up of hands and bag of marijuana

Cannabis is made from the dried flowers and leaves of a plant called Cannabis Sativa. Other names for cannabis are “grass”, “marijuana”, “mull”, “pot”, “dope”, and “yarndi”.​

Last updated: 13 February 2017

What is cannabis?

Is made from the dried flowers and leaves of a plant called Cannabis Sativa. Other names for cannabis are marijuana, grass, mull, pot, dope and yarndi.

Cannabis can look like dried herbs or tea. Sometimes it contains seeds or twigs. It can be grey, green or brown in colour.

Cannabis is usually smoked in hand-rolled cigarettes called joints or in water pipes called bongs. Sometimes it is mixed with food, such as cakes and cookies, and eaten.

What is THC?

THC (tetra hydro cannabinol) is the chemical in cannabis which makes you feel high. This means you experience a change in mood and may see or feel things in a different way.

Some parts of the plant contain a higher level of THC. For example, the flowers or buds have more THC than the stems or leaves.

How does THC affect you?

When cannabis is smoked, THC goes quickly into the blood through the lungs. It then goes to the brain and this is when the high is felt. This can happen within a few minutes and can last up to five hours from each time the smoke is inhaled.

When cannabis is eaten, THC is absorbed more slowly into the blood as it has to pass through the stomach and intestine. Not only does it take longer to experience the high when the drug is used in this way, the effects can also last for much longer, particularly those that are regarded as unpleasant by the user, such as hallucinogenic effects.

THC is absorbed quickly into body fat. It is then released very slowly back into the blood. It can take up to one month for a single dose of THC to fully leave the body.


The effects of cannabis will depend on:

  • how much you take
  • how often you take it
  • how strong the cannabis is
  • how the cannabis is taken (joint, bong, food)
  • your size, weight, health
  • your mood
  • your experience with cannabis
  • your tolerance to cannabis
  • whether cannabis is taken with other drugs, such as alcohol, which can increase the effects of both drugs
  • whether you are alone or with other people, at home or at a party, etc.
  • your age – young people are more vulnerable to the negative effects of cannabis.

Immediate effects

Small amounts

If you have a small amount of cannabis, the effects can last up to five hours from each exposure. You may:

  • feel unusually well and happy
  • do or say things which you normally wouldn’t, such as risk-taking behaviour like unsafe sex or dangerous driving
  • talk and laugh more than usual
  • experience anxiety and paranoia
  • have bad balance and coordination
  • feel drowsy
  • find it hard to concentrate
  • have problems remembering things
  • feel hungry
  • experience asthmatic symptoms or have trouble breathing if you smoke cannabis
  • have a faster heart rate
  • have dry, red eyes
  • have a dry mouth and throat
  • focus on one particular thing and ignore all other things

Large amounts

If you take a large amount of cannabis, you may:

  • feel confused
  • vomit
  • be restless
  • experience change in your perception of time, sound, sight, touch and distance
  • feel excited
  • see or hear things which are not there (hallucinations)
  • feel anxious or panicky
  • ‘black out’
  • feel distant or separate from reality

Cannabis can also cause problems with:

  • remembering things
  • thinking clearly
  • movement
  • ability to do things like drive or operate machines

These symptoms usually disappear when the effects of cannabis wear off.

Long-term effects

If you take cannabis regularly over a long period of time then you may experience the following health problems:

  • dependence
  • increased risk of getting bronchitis, lung cancer and other diseases of the respiratory system
  • decreased motivation
  • decreased concentration, memory and ability to learn new things
  • decreased sex drive
  • depression
  • psychological effects – this is more likely if the person already has a schizophrenic condition or has a pre-disposition to schizophrenia which can be triggered by cannabis use.

Most people who use illegal drugs, first used drugs like alcohol, tobacco or cannabis. However, most people who use cigarettes, alcohol or cannabis never use other illegal drugs.

Regular cannabis use at a younger age increases the risk of other drug use but only 4 per cent of cannabis users have ever used heroin. The link between cannabis use and the use of other illegal drugs is usually due to the personal traits that make it more likely for the person to take part in risky behaviour.


Physical and psychological dependency on cannabis can develop. This means that you may experience withdrawal symptoms if you stop or suddenly cut down as well as tolerance, meaning you need more of the drug to experience the same effects.

Cannabis withdrawal symptoms usually consist of flu-like symptoms such as:

  • headaches
  • nausea
  • irritation
  • depression
  • trouble sleeping and strange dreams
  • anxiety
  • poor appetite
  • restlessness

Mixing with other drugs

It can be dangerous to mix cannabis with other drugs such as alcohol or prescription drugs. This is because the effects of cannabis and the other drug can become stronger and produce more unpredictable effects than if they were used separately.

There is no evidence that cannabis automatically leads to the use of other drugs.


It is not wise to use any drugs during pregnancy. THC passes from the mother to the baby through the placenta. There is some evidence that women who smoke cannabis may give birth to smaller babies or have premature deliveries. Other studies show that newborn babies may have trouble sleeping if their mother used cannabis during pregnancy. Also, in the first six months of life, babies who have been exposed to cannabis in-utero are at a greater risk of developing asthma, chest infections and other breathing problems such as wheezing.

The Law

Using cannabis is illegal in Australia. If you use, sell or give cannabis to someone else and get caught, you could face substantial fines and penalties including a prison sentence. This also includes items used to take cannabis such as bongs. In NSW, first time offenders caught carrying a small amount of cannabis may be issued with a formal caution, which can include information about the harms associated with cannabis use and a number to call for drug related information or referral. A person can only receive up to two cautions.


Cannabis makes it more difficult to drive safely, especially when it is taken with alcohol. It is illegal to drive under the influence of any illicit drugs, including cannabis. If you break this law you could lose your licence for a set time, or be fined or sent to prison.

Since January 2007, police have been conducting random roadside drug testing, and can give any driver a roadside oral drug test. In NSW, if you test positive, you won’t be charged immediately but you will be prohibited from driving for 24 hours. The sample is sent to a laboratory and if it tests positive to cannabis or other drugs, you will be charged to appear in court.

Even where random roadside drug testing is not being carried out, if a police officer suspects you have used drugs you could be arrested and taken to a hospital for a blood and urine test. The samples will be sent to a laboratory and if they test positive to cannabis or any other drug (including prescribed drugs), NSW Police will determine whether your driving would have been impaired by your drug use. You will then be charged accordingly.

Anyone under the influence of cannabis, who kills or injures another person while driving a motor vehicle, can be sentenced to a term in prison.

Information and resources

A series of cannabis factsheets are available for free, from the Your Room​ website.

Quitting cannabis

If you have been taking cannabis for a long period, you may find it difficult to stop. Some people can stop using in one day while others prefer to stop slowly by taking less cannabis each time. The way you choose to stop is a personal one but there is assistance available:

  • The National Cannabis Prevention and Information Centre (NCPIC) provides free resources that can be downloaded from its website:
    • What’s the deal on quitting? A do-it-yourself guide for cannabis users
    • What’s is the deal? Cannabis facts for young people
    • What’s the deal? Cannabis facts for parents
    • What’s the deal? Talking with a young person about cannabis
    • Fast facts on cannabis
    • Fast facts on mental health and cannabis
  • Mulling it over is a harm reduction booklet available from the Manly Drug Education and Counselling Centre (MDECC). Tel. (02) 9977 0711.
  • Counselling for users, concerned relatives and friends is available in some alcohol and other drug agencies, hospitals, community health centres and private clinics. Phone the counselling service in your state or territory for more information.
  • Quit smoking cannabis groups are available in some drug and alcohol agencies. These groups are like quit smoking programs. Phone the counselling service in your state or territory for more information.

For help and support

Alcohol and Drug Information Service (ADIS) is a 24 hour confidential telephone counselling service. Call (02) 9361 8000 or toll free 1800 422 599. Also see Contact a Service for other relevant numbers.