http://goo.gl/MhWqie
The researchers, from McGill University in Canada, have published their results in the American Journal of Public Health.
According to the team, the US and Canada rank number 1 and number 2 in per capita opioid consumption, respectively.
And in 2010 in the US alone, prescribed painkillers were involved in over 16,000 deaths.
Such drugs cause sedation and slow down a person's breathing, but because individuals who are abusing prescription painkillers commonly take larger doses to feel the euphoric effect, their breathing can slow down so much that it stops, resulting in an overdose.
The Centers for Disease Control and Prevention (CDC) state that in 2010, over 12 million people reported using prescription painkillers without a prescription or for the feeling they cause.
Around half of all deaths due to opioids involve at least one other drug, say the CDC. This includes benzodiazepines, cocaine and heroin, as well as alcohol.