Cannabis is a drug that comes from Indian hemp plants such as Cannabis sativa and Cannabis indica. The main active chemical in cannabis is THC (delta-9 tetrahydrocannabinol).
For information on synthetic cannabinoids, see our "Legal high" facts page.
Cannabis is also known as grass, pot, hash, weed, reefer, dope, herb, mull, buddha, ganja, joint, stick, buckets, cones, skunk, hydro, yarndi, smoke and hooch.
What does cannabis look like?
Leaves from the cannabis plant are bright green and have a distinctive shape with five or seven leaflets. The flowering tops and upper leaves are covered in a sticky resin.
How and why is it used?
The different forms of cannabis are used in different ways:
Paper and textiles
Some species of cannabis have few psychoactive effects. These plants are used to produce hemp fibre for use in paper, textiles and clothing.
Cannabis has been used for medical purposes for many centuries. It has been reported that cannabis may be useful to help conditions such as:
The effects of any drug (including cannabis) vary from person to person. How cannabis affects a person depends on many things including their size, weight and health, also whether the person is used to taking it and whether other drugs are taken around the same time. The effects of any drug also depend on the amount taken.
There is no safe level of drug use. Use of any drug always carries some risk—even medications can produce unwanted side effects. It is important to be careful when taking any type of drug.
Low to moderate doses
Low to moderate doses of cannabis can produce effects that last 2 to 4 hours after smoking. The effects of ingested (eaten) cannabis usually start within 1 hour. Some of the effects include:
Long-term cannabis use can have many effects on an individual:
Brain: Impaired concentration, memory and learning ability.
Lungs: Smoking cannabis can result in a sore throat, asthma and bronchitis.
Hormones: Cannabis can affect hormone production. Research shows that some cannabis users have a lowered sex drive. Irregular menstrual cycles and lowered sperm counts have also been reported.
Immune system: There is some concern that cannabis smoking may impair the functioning of the immune system.
Mental health: Cannabis use, especially heavy and regular use, may be linked to a condition known as a “drug-induced psychosis”, or “cannabis psychosis”.
There is some evidence that regular cannabis use increases the likelihood of psychotic symptoms in people who are already vulnerable due to a personal or family history of mental illness. Cannabis also appears to make psychotic symptoms worse for people with schizophrenia, and using cannabis can lower the chances of recovery from a psychotic episode.
Other effects of cannabis use
All areas of a person’s life can be affected by drug use.
Taking cannabis with other drugs
The effects of mixing cannabis with other drugs, including alcohol, prescription medications and over-the-counter medicines, are often unpredictable.
Pregnancy and breastfeeding
Cannabis can be passed on to an unborn baby through the placenta, or to an infant in breast milk.
It is dangerous to drive after using cannabis. The effects of cannabis, such as altered perception, impaired coordination and sleepiness, can affect driving ability. It is especially risky to drive after drinking alcohol and using cannabis, as the combination can increase the effects described above.
Cannabis use in the workplace
Under occupational health and safety legislation, all employees have a responsibility to make sure they look after their own and their co-workers’ safety. The effects of cannabis such as altered perception and impaired coordination can affect a person’s ability to work safely and effectively.
There is evidence that after prolonged use cannabis is addictive. People who use cannabis regularly can develop dependence and tolerance to it, which means they need to take larger amounts of cannabis to get the same effect.
If a dependent person stops taking cannabis, they may experience withdrawal symptoms because their body has to get used to functioning without cannabis. People may experience withdrawal symptoms for less than a week, although their sleep may be affected for longer.
In Australia, there are many different types of treatments for drug problems. Some aim to help a person to stop using a drug, while others aim to reduce the risks and harm related to their drug use. Find out more about treatment.
What to do if you are concerned about someone’s cannabis use
If you are concerned about someone’s drug use, there is help available. Contact the alcohol and drug information service in your state or territory.
What to do in a crisis
Always call triple zero (000) if a drug overdose is known or suspected—and remember that paramedics are not obliged to involve the police.
According to the National Drug Strategy Household Survey, in 2010:
For more statistics about the use of cannabis in Australia, visit our Quick statistics page.
Is it legal?
Federal and state laws provide penalties for possessing, using, cultivating, selling or driving under the influence of cannabis. There are also laws that prevent the sale and possession of bongs and other smoking equipment in some states and territories.
Find out about the Victorian legislation that banned the sale of cannabis water pipes (bongs) from January 2012.
Penalties for cannabis-related offences can include fines, imprisonment and disqualification from driving.
Some states and territories have programs that refer people with a drug problem to treatment and/or education programs where they can receive help rather than going through the criminal justice system.
Please note that this information does not constitute legal advice and should not be relied upon in this way. The information is correct at the time of publication. For information specific to your situation contact a legal aid service in your state or territory.
National drug policy
Australia’s national drug policy is based on harm minimisation. Strategies to minimise harm include encouraging people to avoid using a drug through to helping people to reduce the risk of harm if they do use a drug. It aims to reduce all types of drug-related harm to both the individual and the community.