The medication Narcan might have saved Demi Lovato’s life following her reported overdose. Narcan is an emergency antidote that rapidly reverses the effects of an opioid overdose. It's so effective, it can actually bring people back from the brink of death. Narcan can be found in about every pharmacy across the country. Most states permit the drug to be sold over the counter, no prescription necessary and you don't need to be a medical professional to use it.