Over 115 Americans die every day from opioid overdoses, more than those killed in car accidents, from breast cancer or even guns. Nearly 2.5 million Americans struggle with opioid addiction, and though controversial, some people believe a potentially lifesaving solution may lie in medical marijuana.

In the fourth installment of his groundbreaking series, CNN chief medical correspondent Dr. Sanjay Gupta takes an in-depth look at marijuana’s potential as both an alternative to opioids in treating pain and in ending opioid addiction.