Cannabis

  • Cannabis is a depressant drug
  • 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]. Leaves from the plant are bright green and have a distinctive shape with 5 or 7 leaflets.  The flowering tops and upper leaves are covered in sticky resin. 
  • Cannabis is used for the psychoactive 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 and is the dried leaves and flowers of the plant.  It looks like chopped grass and ranges in colour from grey-green to greenish-brown.  Its texture can be fine or coarse.  Marijuana may contain seeds and stems from the plant.
  • Hashish or hash is dried cannabis resin, usually in the form of a small block ranging in colour from light brown to almost black.  THC concentration is higher than in marijuana, producing stronger effects.
  • Hash oil is a thick oily liquid , golden brown to black in colour, extracted from cannabis.  It is the most potent form of cannabis.
AKA (common names)

Grass, pot, weed, hash, reefer, dope, herb, mull, Buddha, ganja, joint, stick, buckets, cones, skunk, hydro, yarndi, smoke, hooch and green

Low - moderate doses
  • Euphoria
  • Mild enhancement of senses (smell, taste, hearing)
  • Subtle changes in thought and expression
  • Talkativeness
  • Drowsiness
  • Increased appreciation of music
  • Mild closed-eye visuals
  • Anaesthesia
  • Decreased nausea
  • Increased appetite
  • More pronounced visual hallucinations
  • Altered sense of time (Campbell 2001)
High doses

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
Signs of overdose

There is no risk of overdose or death from cannabis use as there are few cannabis receptors in the brainstem which control vital functions (Denning et al, 2004).

Route of administration & onset
  • Marijuana is smoked in hand-rolled cigarettes called joints, or in a pipe or bong
  • Hashish is usually added to tobacco and smoked, or baked and eaten in foods such as hash cookies and cakes
  • Hash oil is usually spread on the tip or paper of a cigarette and then smoked
  • Cannabis and hash can also be smoked in vaporisers that heat the cannabis to temperatures that release its active ingredients while minimising the toxins associated with burning

Onset

  • The THC in cannabis is absorbed into the blood stream through the walls of the lungs if smoked, or through the walls of the stomach and intestines, if eaten. 
  • The blood stream carries the THC to the brain, producing the “high” effects.
  • Smoking cannabis delivers THC rapidly to the blood and brain (Todd et al, 2002).
  • It reaches its peak in approximately ten to twenty minutes and its effects last for around two hours. 
  • When taken orally or ingested, the route of absorption is slower and more variable and the effects are often less pronounced (Todd et al, 2002). 
  • The psychoactive effects of THC last only several hours, however, it can be detected in blood after 20 hours and it accumulates in the tissues of the kidneys, liver, spleen and testes.  THC is stored in fatty tissue (it is lipophilic) and is released slowly and can be detected in the blood three to four weeks after ceasing regular use or following a large dose (Denning et al, 2004).
Duration of effect & 'come down' (half-life)
  • Smoking cannabis delivers THC rapidly to the blood and brain (Todd et al, 2002).
  • It reaches its peak in approximately 10 to 20 minutes and its effects last for around 2 hours. 
  • When taken orally or ingested, the route of absorption is slower and more variable and the effects are often less pronounced (Todd et al, 2002). 
  • The psychoactive effects of THC last only several hours, however, it can be detected in blood after 20 hours and it accumulates in the tissues of the kidneys, liver, spleen and testes. 
  • THC is stored in fatty tissue (it is lipophilic) and is released slowly and can be detected in the blood three to four weeks after ceasing regular use or following a large dose (Denning et al, 2004).
Mechanism of action (on the brain)
  • Activates cannabinoid receptors. 
  • Also increases dopamine activity in the mesolimbic pathway.
Tolerance (dependence) & withdrawal

Dependence on cannabis means that the person needs to use cannabis just to feel ‘normal’ (neuroadaptation).

Signs & symptoms include:

  • tolerance to the effects of cannabis, meaning that more cannabis is needed to get the same effect;
  • withdrawal symptoms from cannabis, such as irritability, trouble sleeping and depressive symptoms;
  • using more cannabis than was intended;
  • persistent desire to stop using cannabis or to cut down and being unsuccessful at this;
  • spending a lot of time obtaining, using or recovering from the use of cannabis;
  • giving up important activities in favour of using cannabis; 
  • using cannabis even when it is known that it causes problems.

The most common symptoms include:

  • anxiety/nervousness
  • restlessness/physical tension
  • reduced appetite
  • mood swings/irritability/restlessness
  • cravings to smoke cannabis
  • sleep difficulties including insomnia and strange dreams
  • Even though these symptoms are not life threatening, they can be distressing enough for the person trying to stop using cannabis, to start again.

What are the symptoms of cannabis withdrawal?

When people stop using cannabis after prolonged use (either because they cannot get any or because they are trying to quit) they may experience a variety of withdrawal symptoms including:

  • sleep difficulties including insomnia and strange dreams
  • mood swings/irritability
  • depression
  • anxiety/nervousness
  • restlessness/physical tension
  • reduced appetite
  • nausea
  • sweats
  • cravings to smoke cannabis

Whilst individual symptoms can be relatively mild, in combination they can still contribute to why a person keeps using cannabis and why they may relapse if trying to quit.

http://ncpic.org.au/ncpic/publications/factsheets/article/cannabis-and-dependence

Short-term harms & risks
  • diminished psychomotor performance
  • reddening of the conjunctiva of the eyes (blood shot eyes)
  • dry mouth/dry eyes
  • sinusitis
  • pharyngitis (throat inflammation)
  • bronchitis
  • anxiety
  • paranoia
  • panic
  • depression
  • dysphoria
  • depersonalisation
  • hallucinations
  • reduced ability to concentrate
  • tiredness
  • confusion 
Long-term harms & risks
  • diminished psychomotor performance
  • dose-related tachychardia (increased heart rate)
  • immunosuppression, including decreased white blood cell count
  • chronic sinusitis
  • chronic pharyngitis
  • chronic bronchitis
  • abnormality of cells lining respiratory tract
  • lung cancer
  • shortened attention span
  • decreased judgment
  • impaired concentration skills
  • deterioration in interpersonal relations
  • profound short-term memory loss
  • attrition of planning, computational and reasoning skills
  • intense focus on present time and loss of future orientation (Campbell 2001)
  • 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.
Further Resources
  • Campbell, A. (2001)  The Australian Illicit Drug Guide: Every person’s guide to illicit drugs – their use, effects and history, treatment options and legal penalties, Schwartz Publishing Pty Ltd, Melbourne
  • Denning, P., Little, J. & Glickman, A. (2004)  Over the Influence: The Harm Reduction Guide for Managing Drugs and Alcohol.  The Guildford Press, New York, New York.
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