Addiction

The lowdown on the UK's most widely used illegal drug.

Medicinal
Not everyone uses cannabis to get stoned. It can be also be used as relief for various health problems. This isn't a new discovery – back in the 1600s in Europe, hemp was used for alleviating aches and pains. In the 1830s, British visitors to India found it was used as an analgesic, anti-convulsant and muscle relaxant. By the 1890s, cannabis preparations were used in the UK for coughs, fatigue, asthma, rheumatism, migraine and period pains.

In 1973 an amendment to the Misuse of Drugs Act 1971 banned the medical use of cannabis and its derivatives. But since then there has been increasing interest in the therapeutic potential of cannabis.

Research and anecdotal evidence show that cannabis can be used for asthma, glaucoma, mild to severe pain and muscle spasms, muscular spasticity, multiple sclerosis, anorexia, mood disorders and convulsive disorders. The recent identification of anandamide, a cannabinoid receptor in the brain and body, has led to speculation that cannabis could be used for some psychological or physical disorders.

Currently, prescriptions for some synthetic forms of THC (delta-9-tetrahydrocannabinol, the most important psychoactive compound in cannabis), are given for chemotherapy- and radiotherapy-related nausea in cancer patients where other drugs have been less effective.

Recreational use
Cannabis is the most popular illegal drug in the UK: an estimated 42% of people aged between 16 and 29 have used it.

Like alcohol, people often smoke cannabis with friends in a social setting. Small amounts can make you feel relaxed, happy, talkative and think that everything's funny. Many users also feel that their senses are heightened, so they experience colours and music more vividly. With large amounts, or very strong cannabis, there may be mild hallucinations of colours and patterens. The effects can last several hours. If you eat hash instead of smoking it, the effects come on more slowly and last longer.

If you're a light, recreational user, you might feel some short-term bad effects, especially if you're not used to cannabis, it's stronger than you expect, or you're smoking it with people you're not comfortable with. Cannabis can make you anxious, panicky, paranoid, confused or depressed, particularly if you're very stoned. You might feel forgetful and have trouble concentrating. After smoking, you might find it hard to sleep.

Heavy use
What about people who smoke all the time? While cannabis isn't physically addictive like heroin, and it's possible to smoke a small amount over a long period of time, some people increase their use and become psychologically dependent, so that they find it hard to get through the day without a spliff.

This means they're causing damage to their lungs in the same way a tobacco smoker would, and risking bronchitis and lung cancer in the future. It's also suggested that very heavy cannabis use inhibits your lungs' ability to fight infection.

A heavy user may lack energy, and perform poorly at work or in education, due possibly to cannabis-related problems involving memory and attention span. They might also find it hard to interact socially without the drug. However, this doesn't apply to all cannabis users. What is more worrying is the link between cannabis and existing mental health problems, such as schizophrenia.

Cannabis in itself does not cause schizophrenia or psychosis, but many mental health professionals think it can be a major factor in the onset of those conditions if you are already at risk of them or have a history of mental health problems.

The strong stuff
One thing that's also worrying health professionals is the increased use of skunk. Skunk is a strong form of cannabis that has much higher levels of THC than usual – average cannabis (hash or weed) about 2–4%, whereas skunk is more like 10–14%.

The effects are similar to cannabis, but much stronger and faster. Some people report that they're closer to the effects of drugs like LSD – more like a trip than being stoned. If you're not used to the effects, or were expecting something more manageable, skunk can be very scary. People sometimes experience anxiety attacks and nervousness, and can feel sick. Anecdotal evidence also suggests that the effects of skunk can go on for longer than with weaker forms of cannabis, with some users still feeling a slight effect days afterwards. However, there's no evidence yet of what skunk's long-term psychological effects could be.

Do you have a problem with cannabis?
All kinds of people smoke cannabis – there isn't a 'typical' user. Gary Sutton, Head of Drugs Services for Release, says, 'With heroin users, in my experience, dependence is always linked to a depressive personality, but cannabis use is heavily individualised. So someone may smoke two joints a week, or even a month and not increase that consumption.'

If you're worried about your cannabis use, try answering the following questions. The more 'yes' answers, the more likely it is that you need change your use. There are some tips on cutting down and a more specific quiz on the Know Cannabis website.

Do you to smoke on a daily basis just to feel normal?
Do you need to use more and more to get the effect you want?
Have you tried to give up or cut down, and failed?
Do you avoid people or places that do not approve of you using cannabis?
Does cannabis use interfere with your sleeping or eating?
Do you think a lot about cannabis?
Have you ever thought you couldn't fit in or have a good time without drugs?
Has your work or education suffered as a result of cannabis use?
Have you ever stolen cannabis or stolen money to obtain cannabis?
Have you ever used cannabis because of emotional pain or stress?
Has using cannabis affected your relationships with family, friends or partners?