https://en.wikipedia.org/wiki/Naloxone
Best of all, it doesn't have a lot in the way of side effects. If you haven't taken any opioids, about the worst thing that can happen is you might discover you've got some pain that naturally produced endorphins were masking.
So you might wonder, why isn't this shit available everywhere all the time? I mean, might that not save some lives, given the epidemic of opioid abuse that white people around the country are suffering from?
http://www.reuters.com/article/us-cvs-health-nalaxone-idUSKCN0VA38U
"CVS Health Corp said it would make the opioid overdose antidote, naloxone, available without a prescription at all its pharmacies across Ohio, a state with one of the highest rates of overdose-related deaths." It was already available without a prescription in several states, but this is a commitment to a higher degree of availability. Judging by those two medic memoirs I just read (_A Thousand Naked Strangers_, and _Welcome to New Orleans ... How Many Shots Did You Hear?_), one of the biggest issues involved in getting naloxone into a person who has od'd is not being sure that's why the person is unconscious and not breathing -- and bystanders who are more worried about being prosecuted for drug abuse than getting the person who is (nearly) dead back in the realm of the living again. (Look, if people who abused opioids had good judgment, they wouldn't abuse opioids, so it shouldn't be a surprise that they tend to make that kind of choice under pressure.)
Naloxone is rapidly joining the EpiPen in availability to people who are (sort of) first responders.
http://www.wlky.com/news/coalition-provides-free-naloxone-kits-and-training/37756222
I hope this helps. Apparently more people are dropping annually from opioids than die in auto accidents. We really need to fix this.