Cannabis (marihuana / hashish) is obtained from the plant Cannabis Sativa, and contains approximately 60 different psychoactive chemicals called cannabinoids ( plus a further 360 other active constituents ). The major cannabinoid found in cannabis is tetrahydrocannabinol (THC). Cannabis can be used in a number of forms - as resin (hashish), a dried slightly oily caked block made from the tops and leaves of the female plant; as an oil extract; or as marihuana (grass) the dried plant.

Cannabis in these forms is generally rolled into a cigarette (a joint / spliff) often with tobacco, and smoked. However, they can be eaten or brewed into a tea. Cannabis is not suitable for injecting.

The effect of cannabis depends very much on the expectations and mood of the user, the quantity taken and the possible presence of other drugs, such as alcohol, in the body. Generally, people expect to experience a pleasurable state of relaxation, with heightened sensory experiences of taste, sound and colour etc.

THC does have some medical uses. Its anti-emetic properties (inhibits vomiting) are particularly useful in the treatment of cancer patients on chemotherapy. Also, as THC increases the appetite and reduces the vomit response, it is starting to be used in the treatment of anorexia and other eating disorders. In both cases THC is extracted from the plant matter and is administered in its pure form as tablets.



While intoxicated, users are likely to show a reduced concentration, short-term memory, intellect and manual dexterity. Users are also likely to experience an increase in appetite and increased thirst.

High doses of cannabis can sometimes cause confusion and distortions in perception, therefore, individuals with underlying psychological disorders are ill advised to use cannabis regularly or in high doses as it may aggravate their condition.

The effect of smoking cannabis starts within a few minutes and lasts between an hour (for low doses) to several hours (higher doses). There is virtually no danger of fatal overdose.



There is no conclusive evidence to suggest long term physical or psychological damage from extended cannabis use. However, some small studies have suggested that, along with tobacco smokers, heavy cannabis users risk lung cancer, chronic bronchitis and other respiratory diseases, because of the higher tar content in cannabis smoke.

Various other studies have suggested the possibility of chromosome damage, blockage of blood vessels, chronic diarrhoea, and persistent cramps, all as a result of heavy prolonged use, BUT little direct evidence exists from longitudinal studies.

It has also been suggested that some heavy users suffer from "amotivational syndrome" meaning that they show a lack of energy and interest, slow and confused thinking, impaired memory and general apathy. This condition is said to disappear soon after drug use stops. however, evidence for this syndrome is contradictory. Contradictory evidence also exists for the condition of 'cannabis psychosis'. Symptoms have been suggested ranging from confusion and anxiety, to schizophrenic type paranoia.

Traditionally, cannabis has been regarded as having minimal tolerance effects, physical dependence, or withdrawal syndrome other than 'post-drug' irritability and fatigue. However, as more research is starting to be done on long term cannabis use, there is some evidence to suggest that both physical and psychological dependence can develop to the effects of THC with repeated contact. It is suggested withdrawal may involve symptoms such as disturbed sleep and eating patterns, sweating, nausea, muscle cramps and diarrhoea.



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