Animal tranquilizers found in illegal opioids may suppress the lifesaving medication naloxone − and cause more overdose deaths

The animal tranquilizers xylazine and medetomidine are in approximately one-third of the illegal opioids available in the U.S., including fentanyl, heroin and oxycodone. Animal tranquilizers enhance the user’s euphoric high from opioids, particularly in those who have developed a tolerance to the opioid. But adding the tranquilizers to these already illicit drugs could keep naloxone, a medication known to prevent deaths from opioid overdose, from working.

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