Cannabis can help make pain easier to bear, but is less effective at actually reducing pain levels, new research suggests.

Researchers from the University of Oxford in England, using brain scans, found that the ingredient in cannabis that gets you 'high' reduced the brain activity linked to the emotional aspects of pain.

But the effect on the pain experienced varied greatly, it was found.

The researchers recruited 12 healthy men to take part in the study. They were given either a tablet of THC, the ingredient that is responsible for the 'high' with cannabis - or a placebo.

The volunteers then had a cream rubbed in to induce pain, which was either a dummy cream or a cream that  caused a burning sensation.

Each participant had four brain scans to see how their brain activity changed when their perception of the pain reduced.

It was found that with cannabis, generally people didn't report any change in the pain or discomfort, but it bothered them less thanks to the cannabis.

It is speculated that the findings could help predict patients who would benefit from taking cannabis for pain relief.

The research is published in the journal Pain.