Medical cannabis could be a viable substitute for effective, but highly-addictive, opioids often used for pain relief, a new survey suggests, as researchers continue to explore the potential health benefits of cannabis amid a growing national opioid crisis.  Of the more than three-fifths of the participants in the survey who had been taking opioids —including oxycodone and codeine — before they were prescribed medical cannabis, 79% were able to stop or reduce the use of them once they started using medical cannabis.  Read the article here.