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

What is cannabis?

Effects of cannabis


Further information



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What is cannabis? 

Cannabis is a depressant drug, which means it slows down messages travelling between your brain and body. When large doses of cannabis are taken, it may also produce hallucinogenic effects. The main active chemical in cannabis is THC (delta-9 tetrahydrocannabinol).

Other names 

Marijuana, yarndi, pot, weed, hash, dope, gunja, joint, stick, Kronic (synthetic form), cone, choof.

How is it used?

Cannabis is usually smoked or eaten and comes in 3 different forms:

  • Marijuana − the dried plant that is smoked in a joint or a bong. This is the most common form.
  • Hashish – the dried plant resin that is usually mixed with tobacco and smoked or added to foods and baked; such as cookies and brownies.
  • Hash oil – liquid that is usually added to the tip of a cigarette and smoked.

It takes about an hour to feel the effects of eating cannabis, which means it’s easy to have too much. If it’s smoked the effects are usually felt straight away. However, smoking can cause a number of negative side effects, especially later in life.

Cannabis can also come in synthetic form, which may be more harmful than real cannabis. Read more about synthetic cannabis.

    Effects of cannabis

    There is no safe level of drug use. Use of any drug always carries some risk. It's important to be careful when taking any type of drug.

    Cannabis affects everyone differently, but effects may include:

    • Feeling relaxed and sleepy
    • Spontaneous laughter and excitement
    • Increased appetite
    • Dry mouth
    • Quiet and reflective mood

    If a large amount or a strong batch is taken, the following may also be experienced:

    • Trouble concentrating
    • Blurred vision
    • Clumsiness
    • Slower reflexes
    • Bloodshot eyes
    • Seeing and hearing things that aren't there
    • Increased heart rate
    • Low blood pressure
    • Mild anxiety and paranoia

    Long-term effects 

    Regular use of cannabis may eventually cause:

    • Memory loss
    • Learning difficulties
    • Mood swings
    • Regular colds or flu
    • Reduced sex drive
    • Difficulty having children (low fertility in males and females)
    • Needing to use more to get the same effect
    • Dependence on cannabis
    • Financial, work and social problems

    Smoking cannabis can also cause:

    • Sore throat
    • Asthma
    • Bronchitis
    • Cancer (if smoked with tobacco)

    Those with a family history of mental illness are more likely to also experience anxiety, depression and psychotic symptoms after using cannabis. Psychotic symptoms include delusions, hallucinations and seeing or hearing things that do not exist or are distorted. Read more about cannabis and mental health.

    Using cannabis with other drugs

    The effects of taking cannabis with other drugs − including over-the-counter or prescribed medications − can be unpredictable and dangerous.

    Cannabis + alcohol: nausea, vomiting, panic, anxiety and paranoia.

    Cannabis is sometimes used to help with the ‘come down’ effects of stimulant drugs, such as ice, speed and ecstasy. However, doing this can cause reduced motivation, bad memory,  mental health problems and dependency on both drugs.


    Giving up cannabis after using it for a long time is challenging, because the body has to get used to functioning without it. Withdrawal symptoms may last for only a week, but sleep may be affected for longer. Symptoms include:

    • Anxiety
    • Irritability
    • Aggressive and angry behaviour
    • Loss of appetite and upset stomach
    • Sweating, chills and tremors
    • Restless sleep and nightmares

    Find out more about withdrawal.

      Further information



      Reducing the risks




      ADF SEARCH – Find further credible research and information on cannabis.

      ADIN – Find other credible websites and apps on cannabis.



      Last updated: 25 January 2014

      Information you heard is intended as a general guide only. This audio is copyrighted by the Australian Drug Foundation. Visit for more