The leaves and buds of the cannabis plant have been used in herbal remedies for over 3000 years for conditions as varied as malaria and constipation. In the Middle Ages cannabis was used as a pain killer, particularly for rheumatic pain.

In recent years more some 66 different active chemicals have been identified in the cannabis, marijuana, plant and these are called cannabinoids. In the UK a synthetic, man made, version of one of these cannabinoids is available on prescription as a drug called Nabilone (although the use of cannabis, or marijuana, in its natural form remains illegal).

Cannabis does have some analgesic (pain killing) effect and at least 5 clinical trials have been carried out comparing cannabis or cannabinoid drugs with more conventional pain killers for people who have pain due to a cancer. These have shown that the pain killing benefit of cannabis or cannabinoids is no better than ordinary codeine (a widely used analgesic, available on prescription or as an ingredient in many over the counter pain killers).

Whilst this means that cannabis, or cannabinoids, might help ease mild or moderate (but not severe) pain their side effects make them undesirable. These include sedation, confusion, altered perception of time and space, low blood pressure and palpitations. Marijuana also contains chemicals which can cause cancer (carcinogens) and smoking the drug can cause respiratory problems. The cannabinoid drugs also share a number of these side effects.

So because there are many other pain killers which are just as, if not more, effective and because of the side effects they cause, neither cannabis nor cannabis extracts are recommended as a treatment for pain control.