Cannabis factsCannabis. Different forms of cannabis including dried leaves and resin block. © Australian Drug Foundation 2010.

What is cannabis?

Effects of cannabis

Tolerance and dependence

Getting help

Cannabis use in Australia

Cannabis information for parents

What is cannabis?

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).

Cannabis is a depressant drug. Depressant drugs do not necessarily make you feel depressed. Rather, they slow down the activity of the central nervous system and the messages going between the brain and the body. When large doses of cannabis are taken it may also produce hallucinogenic effects.

For information on synthetic cannabinoids, see our "Legal high" facts page.

Other names

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.

Cannabis is used for the psychoactive (mind and mood-altering) effects of THC and other active ingredients. THC is the chemical in cannabis that makes you feel “high”.

There are three main forms of psychoactive cannabis: marijuana, hashish and hash oil.

Marijuana is the most common and least potent form of cannabis. Marijuana is the dried leaves and flowers of the plant.

Hashish (“hash”) is dried cannabis resin, usually in the form of a small block. The concentration of THC in hashish is higher than in marijuana, producing stronger effects.

Hash oil is a thick, oily liquid, golden brown to black in colour, which is extracted from cannabis. Hash oil is the strongest form of cannabis.

How and why is it used?

The different forms of cannabis are used in different ways:

  • Marijuana is smoked in hand-rolled cigarettes (joints), or in a pipe (a bong).
  • Hashish is usually added to tobacco and smoked, or baked and eaten in foods such as hash cookies.
  • Hash oil is usually spread on the tip or paper of a cigarette and then smoked.

Cannabis and hash can also be smoked in a vaporiser. Vaporisers heat cannabis to temperatures that release its active ingredients while minimising the toxins associated with burning.

The THC in cannabis is absorbed into the bloodstream through the walls of the lungs (if smoked), or through the walls of the stomach and intestines (if eaten). The bloodstream carries the THC to the brain, producing the “high” effects. Drugs inhaled get into the bloodstream quicker than those eaten. This means that the effects of cannabis when smoked occur more rapidly than when eaten.

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.

Medical uses

Cannabis has been used for medical purposes for many centuries. It has been reported that cannabis may be useful to help conditions such as:

  • nausea and vomiting, particularly when associated with chemotherapy
  • wasting and severe weight loss, in people with HIV/AIDS, cancer, or anorexia nervosa, as it may be used as an appetite stimulant
  • pain relief, for example in people with cancer and arthritis
  • relief from symptoms of some neurological disorders that involve muscle spasms, including multiple sclerosis and spinal cord injury
  • glaucoma
  • epilepsy
  • asthma.

Effects of cannabis

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.

Immediate effects

  • loss of inhibition
  • spontaneous laughter
  • quiet and reflective mood
  • affected perception including sound, colour and other sensations
  • confusion
  • altered thinking and memory
  • anxiety
  • mild paranoia
  • altered vision
  • reddened/bloodshot eyes
  • relaxation
  • sleepiness
  • reduced coordination and balance
  • increased heart rate
  • low blood pressure
  • increased appetite.

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:

Higher doses

  • confusion
  • restlessness
  • excitement
  • hallucinations
  • anxiety or panic
  • detachment from reality
  • decreased reaction time
  • paranoia.

Long-term effects

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

Social problems

All areas of a person’s life can be affected by drug use.

  • Disagreements and frustration over drug use can cause family arguments and affect personal relationships.
  • Legal and health problems can also add to the strain on personal, financial and work relationships.

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.

When people drink alcohol and use cannabis at the same time, they may have strong reactions such as nausea and/or vomiting, panic or paranoia.

Some people use cannabis to come down from stimulants such as amphetamines or ecstasy. The mixing of cannabis and ecstasy has been linked to reduced motivation, impaired memory and mental health problems.

Pregnancy and breastfeeding

Cannabis can be passed on to an unborn baby through the placenta, or to an infant in breast milk.

Find out about the effects of cannabis during pregnancy and breastfeeding.


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.

Read more about the effects of cannabis on driving.

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.

Tolerance and dependence

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.

Dependence on cannabis can be psychological, physical, or both. People who are dependent on cannabis find that using the drug becomes far more important than other activities in their life. They crave the drug and find it very difficult to stop using it. People who are psychologically dependent on cannabis may find they feel an urge to use it when they are in specific surroundings or socialising with friends. Physical dependence occurs when a person’s body adapts to cannabis and gets used to functioning with the cannabis present.


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.

Some of the withdrawal symptoms that may be experienced include:

  • cravings for cannabis
  • loss of appetite and weight loss
  • irritability
  • anxiety
  • sweating
  • upset stomach
  • chills and tremors
  • increased body temperature
  • disturbed and restless sleep, often interrupted by nightmares.

Getting help


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.

If someone overdoses or has an adverse reaction while using cannabis, it is very important that they receive professional help as soon as possible. A quick response can save their life.

Visit the Better Health Channel to read St John Ambulance’s advice on drug overdose.

Cannabis use in Australia

According to the National Drug Strategy Household Survey, in 2010:

  • over 35.4 % of Australians aged over 12 years have used cannabis in their lifetime

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.

Read more about drug laws in Australia.

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.