Dose

In high doses or with stronger types of cannabis (for example skunk) there may be nausea, hallucinations and anxiety or paranoia, especially in people already feeling anxious or depressed. Using bongs is more harmful than joints because you breathe in more drug and smoke.

The down side

Cannabis can cause confusion, short-term memory loss, slow reflexes and coordination difficulties, so driving, operating machinery etc should be avoided.

Feeling ‘woolly-headed’ is an after-effect.

The drugs effects can be stronger and last much longer if it's eaten, instead of smoked, as it's harder to control the amount used.

Smoking the drug can cause or aggravate chest/breathing complaints including bronchitis and asthma.

Cannabis has more cancer-causing agents in it than tobacco (see the section on Mixing lower down this page).

Problem use

Long-term use can lead to lack of motivation and lasting poor memory and attention span - the famous ‘dope head’. This might not go away once cannabis use stops.

Some people can come to rely heavily on cannabis and find it hard to stop using it.

At risk

It seems cannabis may trigger mental health problems such as depression or schizophrenia in a small number of people. This is more likely when the person starts using the drug in adolescence, uses the drug a lot, uses the stronger types or already has an underlying predisposition towards mental illness (which they may not realise they have).

Those with heart and circulation problems should avoid cannabis as even in low doses it raises blood pressure and heart rate.

Some people smoke cannabis for relief from:

• muscular pain
• multiple sclerosis
• cancer (it combats nausea from chemotherapy)
• HIV/AIDS (increases appetite)
• glaucoma (lowers pressure on the eye).

The drug's active ingredient has been made into a prescription medicine so that patients can enjoy its medical benefits without risking the harm that comes from smoking it (and without the high).

Mixing - with tobacco

Smoking the drug with tobacco carries a high risk of becoming addicted to nicotine, along with the risk of smoking-related illnesses including cancer, heart disease and breathing problems. Smoking cannabis could be worse for health than smoking tobacco on its own as:

• cannabis has more cancer-causing agents in it than tobacco
• cannabis smokers inhale deeper and for longer
• cannabis has much higher levels of tar than tobacco

Cannabis smokers who also smoke cigarettes have very high levels of tar intake. But some claim this is balanced out by the fact people usually smoke spliffs less often than they smoke cigarettes.

The harmful effects of smoking can be avoided by eating it.

With stimulants

Cannabis might take the edge off stimulants like cocaine and speed.

With ketamine

Smoking dope when taking the anaesthetic drug ketamine could lead to burns or accidental fires.

With HIV Med

There are no known dangerous reactions with HIV drugs.

The law

Cannabis is not legal. In 2009 it was reclassified upwards from a Class C drug to Class B. Possession can now mean up to 5 years in prison and/or an unlimited fine. Intending to supply (including giving to friends) can mean up to 14 years in prison and/or unlimited fine.

If you're under 18 - You can be arrested, taken to a police station and can expect a reprimand for your first offence, a final warning for your second offence or a criminal charge if it's your third offence.

If you're over 18 - You can expect a warning for your first offence, an £80 on the spot fine for your second offence and a criminal charge for your third offence.

This 'three strikes' penalty system applies to England and Wales. In Scotland and Northern Ireland the old penalty system that covers Class B drugs applies instead.

The law treats smoking cannabis openly in public or near children (eg. near a school) more seriously.

Using the drug for medical reasons is not legal.

Growing cannabis plants is illegal, as is letting people smoke it in premises you're responsible for, including your home.

Driving

Cannabis causes sleepiness, worsens concentration, distorts perception and slows reaction time. Driving under its influence can lead to the same penalty as drunk driving, with one or more of the following penalties:

• one year driving ban
• up to £5,000 fine
• up to six months in prison.

If someone dies as a result of your driving then up to 14 years in prison is possible and a driving ban of up to two years.

More information and support

If your cannabis use worries you, check out the self-help plan at www.knowcannabis.org.uk

For help and advice concerning drugs see the page of Useful info and support in the Power room on this website.