Cannabis is most often used for its relaxing properties. Since its non-medical use is illegal in many countries including UK and Philippines, the number of users is only an estimate ( up to 200 million worldwide ). As with other illicit drugs, that's far fewer than for alcohol or tobacco.
Just how effective - and safe - is it ?
The plant is usually rolled into a cigarette, but can also be smoked in a pipe, brewed as a tea or mixed with food. It can't readily be injected. It's a mild sedative, releasing inhibitions, and is mildly hallucinogenic. Cannabis extract may be prescribed in the UK ( "Sativex" ) for multiple sclerosis.
1. Acute toxic effects / overdose : Unlike other common illicit drugs, it's difficult or impossible to overdose fatally on cannabis.
2. Intoxication : cannabis impairs thinking and behaviour, especially for sustained attention tasks like driving. There is a risk of road traffic accidents, but much less than that for alcohol.
3. Dependence : cannabis is the illicit drug most commonly used and most widely available. Despite this, it seems only a minority - perhaps 1/10 - become dependent. There is an association between use of alcohol and tobacco, followed by cannabis, and then other illicit drugs. Risk factors often co-occur - young males with social and family disadvantages, poor performance at school, and peer pressures. Psychotic illness like schizophrenia is more likely in vulnerable individuals. It's not proven to cause depression or suicide.
4. Chronic diseases : a. Emphysema ( increased size of air spaces in lungs due to damage ). As with tobacco smoke, common sense suggests that inhaling smoke from any burning object is harmful. There's some evidence that heavy cannabis users may be at risk of emphysema.
b. Cancer. Cannabis smoke contains cancer-forming substances, and it's often mixed with tobacco when smoked. But we don't know yet for sure whether or not cannabis itself causes cancer.
There are many problems in deciding how safe cannabis is. There is the unintended consequence of it being illegal. In such countries it's hard to get accurate data on usage and possible adverse health consequences. Despite use for thousands of years, there is less good evidence than you might expect. " Confounding variables " are the large number of chemicals ( around 400 ) in cannabis, and the fact that it's often taken with tobacco, alcohol, or other drugs. The whole topic is controversial, emotive, and influenced by a huge amount of anecdotal evidence. We don't even know how much harm from cannabis ( and other drugs ) derives from illegal status, or how much that status reduces its use.
