The overdose crisis continues unabated. While the epidemic was originally fueled largely by prescription opioid pain relievers, around 2010 a dramatic increase in heroin-related overdoses began. After remaining essentially stable for years, overdose deaths involving heroin spiked rapidly, more than tripling between 2010 and 2014. Starting in 2014, the epidemic began another transformation. Black market drug products—both heroin and counterfeit pills - became increasingly adulterated with illicitly—manufactured synthetic opioids, mainly fentanyl analogues.