Cannabis use
What is cannabis?
Cannabis comes from the plant Cannabis sativa. The main active ingredient in cannabis is delta-9-tetrahydrocannabinol (D9THC). It is D9THC that gives users the ‘high’.
The drug comes in 3 main forms:
- marijuana — the dried leaves or flowers (heads) of the plant;
- hashish (or ‘hash’) — dried blocks of cannabis resin; and
- hash oil — extracted from hashish.
Marijuana is usually smoked in hand-rolled cigarettes (joints) or in a water pipe (bong). Hashish can also be smoked or added to food and eaten (e.g. ‘hash cookies’).
How common is cannabis use?
Cannabis is the most commonly used illegal drug in Australia. In the latest National Drug Strategy Household Survey (2004), about a third of the population reported having used cannabis at some time in their lives.
What are its effects?
Acute intoxication
The effects of acute intoxication with cannabis (being ‘stoned’ or ‘high’) may include:
- a sense of wellbeing;
- feeling relaxed and drowsy;
- altered perceptions (for example, of time and space);
- impairment of memory, concentration and problem solving;
- loss of co-ordination;
- dry mouth and red eyes; and
- a drop in blood pressure and an increase in heart rate.
With higher doses of the drug there may also be:
- panic and anxiety;
- confusion; and
- paranoia and hallucinations.
Psychosis
Heavy cannabis use may cause an acute toxic psychosis (a mental state in which a person loses contact with reality). Also, in people who already have schizophrenia, cannabis use can cause their psychotic symptoms to worsen.
Physical health
Because cannabis users often also smoke tobacco, it is difficult to separate the effects of cannabis on physical health from the effects of tobacco. Possible long-term effects of cannabis use may include increased risk of chest infections, chronic bronchitis and cancers of the lungs, head and neck. Chronic cannabis use can also affect fertility in men and women.
Dependence
About one in 10 users will become dependent on cannabis. Many regular users find it hard to stop using cannabis, even though they may want to.
Treatments for cannabis dependence
For those cannabis users who do become dependent, treatment with cognitive behavioural therapy — a type of psychological therapy that's also known as CBT — may help them to cut down on their use.
Last Reviewed: 19 May 2006
