Too much cannabis 'worsens pain'

More isn't always better:

The pain-relieving qualities of cannabis have long been hailed, and several countries have made it available for medicinal purposes.

But quantity is key, according to the study in the journal Anesthesiology.

...those who had smoked the moderate dose said their pain was much better, while those who consumed high doses said it had got worse.

They did, however, feel "higher" than counterparts who had taken moderate doses.