Diseases & Conditions
The debate over the use of cannabis in medicine is highly controversial and emotive.
Supporters of the drug claim it has wide-ranging benefits, but opponents say it is a potentially dangerous substance that can actually damage health.
There is scientific evidence to suggest that cannabis may be useful in treating a wide range of conditions.
And wide-scale trials testing the safety and efficacy of cannabis extracts are currently underway in the UK and elsewhere.
For instance, cannabis appears to be able to help reduce the side effects of chemotherapy treatment given to cancer patients.
The drugs used to treat cancer are among the most powerful, and most toxic, chemicals used in medicine. They produce unpleasant side effects, such as days or weeks of vomiting and nausea after each treatment.
Cannabis is an anti-emetic, a drug that relieves nausea and allows patients to eat and live normally.
Extracts also seem to benefit patients suffering from multiple sclerosis, stopping muscle spasms, and reducing tremors.
In the USA, the Food and Drug Administration has approved the oral use of dronabinol, a cannabis derivative, for people with Aids.
There is evidence that cannabis may stimulate the appetites of Aids patients with wasting disease.
It may also help relieve the pain of menstrual cramps and childbirth.
Campaigners claim the drug is useful in treating depression and other mood disorders.
Cannabis analogues have been shown to prevent seizures in epileptic patients when given in combination with prescription drugs.
The drug can also help in the treatment of patients suffering from glaucoma, one of the commonest causes of blindness, by reducing fluid pressure in the eye.
Claims have also been made for its use in treating asthma, strokes, Parkinson's Disease, Alzheimer's Disease, alcoholism and insomnia.
However, opponents of the use of cannabis point to the fact that it damages the ability to concentrate.
There are other side effects of the drug, but they vary considerably and are highly unpredictable, partly because cannabis has more than 400 active ingredients.
A report by the House of Lords Science and Technology Committee recommended the use of cannabis for medicinal purposes.
Doctors are doubtful
But the British Medical Association (BMA) did not give the report 100% support.
The BMA believes only cannabinoids - part of the cannabis plant - should be used in medicine.
Cannabinoids are the active ingredients of cannabis. The BMA says crude cannabis contains many toxic ingredients as well.
It is also worried about how cannabis will be prescribed, saying that smoking the drug is harmful to health.
It wants to see the development of "targeted medicines" using cannabinoids.
The government says it will not consider legalising cannabis for medical use until clinical trials had been completed.