Why You Can Now Get This Opioid Overdose Drug at Walgreens

President Donald Trump declared the opioid crisis a nationwide public health emergency Thursday, the same week Walgreens announced it would start selling Narcan — a drug that can reverse the effects of an opioid overdose — at its pharmacies throughout the country. Both moves come at a time when 91 Americans die from an opioid overdose each day, according to estimates from the Centers for Disease Control and Prevention.

Here's how Narcan works.