Smoking cannabis has been proven to ease pain for people suffering from nerve damage, in possibly the first scientific test to study inhaling the drug.
Canadian scientists tested four different potency levels of herbal cannabis in 21 patients aged between 25 and 77, and found smoking also reduced anxiety and depression.
Patients with chronic neuropathic pain resulting from surgery or traumatic injury were asked to smoke 25 mg from a pipe three times a day, and researchers found no one suffered serious side-effects.
All those inhaling the most potent drug, which contained 9.4% of the active ingredient THC, reported feeling "high" and euphoric on one occasion, but said they felt less pain, anxiety and depression, and slept better.
Some of these patients said they experienced headaches, dry eyes, dizziness, numbness, coughs and a burning sensation after puffing on the pipe, but none showed a significant change in heart rate, kidney function or vital signs.
Previously, clinical trials used cannabis extract in pill form to treat certain types of pain, to avoid claims of patients getting high. It is thought this report, published in the Canadian Medical Association Journal (CMAJ), is the first to study the effects of smoked cannabis.