In recent years, xylazine has increasingly been found as an active cut in the unregulated drug supply, including heroin, fentanyl, cocaine, methamphetamine, and counterfeit prescription pills. Although not a controlled substance federally, several states have moved to schedule xylazine.
Originally limited to Philadelphia and commonly referred to as “tranq” on the streets, xylazine has now been discovered in unregulated substances throughout the United States. Between 2010 and 2015, only 2% of opioid overdose deaths in Philadelphia also involved xylazine, and by 2019, that number had increased to 1 in 3.
https://www.pharmacytimes.com/view/the-impact-of-xylazine-on-overdose-response