Cannabis/marijuana: what are the effects?
The effects of any drug (including cannabis) vary from person to person. It depends on many factors, including an individual's size, weight and health, how the drug is taken, how much is taken, whether the person is used to taking it, and whether other drugs are taken.
Immediate effects
Small doses of cannabis can have effects that last 2 to 4 hours after smoking. These effects include:
- relaxation and loss of inhibition;
- increased appetite;
- affected perception of colour, sound and other sensations;
- impaired co-ordination; and
- affected thinking and memory.
Other common immediate effects include increased heart rate, low blood pressure and reddened eyes.
In greater quantities
Larger quantities of marijuana make the above effects stronger, and also tend to distort a person's perceptions.
Very large quantities of marijuana can produce:
- confusion;
- restlessness;
- feelings of excitement;
- hallucinations;
- anxiety or panic, or detachment from reality;
- decreased reaction time; and
- paranoia.
Long-term effects
Research shows evidence of some long-term effects in some regular cannabis users.
Respiratory illness
Marijuana cigarettes have more tar than tobacco, placing cannabis users at an increased risk of respiratory illness such as lung cancer and chronic bronchitis. Cigarette smokers who also smoke cannabis have an even greater risk of respiratory disease.
Reduced motivation
Many regular users have reported that they have less energy and motivation, so that performance at work or school suffers.
Brain function
Concentration, memory and the ability to learn can all be reduced by regular cannabis use. These effects can last for several months after ceasing cannabis use.
Hormones
Cannabis can affect hormone production. Research shows that some cannabis users have a lower 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.
Cannabis and psychosis
It is believed that cannabis use — especially if heavy and regular — may be linked to a condition known as a drug-induced psychosis, or ‘cannabis psychosis’. This can last up to a few days. The episodes are often characterised by hallucinations, delusions, memory loss and confusion.
There is some evidence that regular cannabis use increases the likelihood of psychotic symptoms occurring in an individual who is vulnerable due to a personal or family history of mental illness. Cannabis also appears to make psychotic symptoms worse for those with schizophrenia and lowers the chances of recovery from a psychotic episode.
Medicinal use of cannabis
Cannabis has been used medicinally for many centuries. There is evidence to suggest it is useful in providing relief from nausea and vomiting caused by chemotherapy, wasting and severe weight loss, pain, glaucoma, epilepsy and asthma.
For more information, please click on the Australian Drug Foundation's DrugInfo Clearinghouse web site link below.
Last Reviewed: 20 September 2006
