What we know from clinical trials

In the period from 1975 to 2012, at least 139 clinical studies were published on herbal cannabis or pure cannabinoids, together including about 9000 patients suffering from a wide range of medical conditions.
Based on this wealth of data it has been confirmed that cannabinoids exhibit a therapeutic potential mainly as analgesic for chronic neuropathic pain, as appetite stimulant and anti-emetic for debilitating diseases (e.g. cancer, AIDS, Hepatitis C), as well as in the treatment of various symptoms of multiple sclerosis

Additionally, cannabinoids show promising results in the symptomatic treatment of spinal cord injuries, intestinal dysfunction, Tourette’s syndrome, hyperactivity and anxiety disorders, allergies, epilepsy and glaucoma
Perhaps one of the most exciting recent findings is that cannabinoids may be effective in the treatment of some forms of cancer, by not just ameliorating symptoms but actually attacking and killing cancer cells. 
However, more studies are needed before cannabis should be recommended for cancer, as explained in more detail below. Clinical studies with cannabis or cannabinoids have often been inspired by positive anecdotal experiences of patients using herbal cannabis products for self-treatment. 
For example, the antiemetic, appetite enhancing, analgesic and muscle relaxant effects, and the therapeutic use of cannabinoids in Tourette’s syndrome, were all discovered or rediscovered because patients kept telling scientists and politicians about it. 

This clearly indicates the critical role that collecting data on actual patient experiences has played - and may continue to play – in our evolving understanding of cannabis effects. It is interesting to note that in recent years some well-designed studies on the effects of smoked cannabis have been published, mainly in studies on HIV/AIDS. 
This is of specific interest because most patients self-medicating with cannabis administer their medicine by smoking, while virtually no clinical trial has dared to study this controversial administration form. Such studies particularly show a benefit on neuropathic pain and appetite. 
Obviously, the noxious byproducts (tar, carbon monoxide, ammonia, etc.) released through combustion remain a reason to advice against smoked cannabis. Specific herbal vaporizers have been developed to provide a safer and more efficient delivery system for inhaling cannabis. It is reasonable to assume that future clinical trials will utilize this alternative delivery method more frequently.
Subpages (1): Multiple Sclerosis