All About Xylazine

Xylazine (known as “tranq”) is a non-opioid, alpha₂-agonist used as an animal tranquilizer and not approved for human use. It has been found in the street opioid supply in increasing quantities since 2008. Xylazine was found in 91% of heroin or fentanyl samples in Philadelphia in 2021.

Xylazine is a central nervous system depressant that can cause drowsiness and sedation as well as decreasing respirations, heart rate, and blood pressure.

Patient reports and epidemiologic trends suggest that xylazine is contributing to an increased incidence of wounds. Some patients with chronic xylazine exposure may also develop a withdrawal syndrome. Little research exists to describe the incidence, characteristics, or effective management of xylazine wounds or a xylazine withdrawal syndrome.

As we build evidence, all clinicians caring for individuals who use drugs should be aware of xylazine’s presence in the drug supply. Although some patients may require treatment specific to xylazine exposure, in general we encourage clinicians to continue to follow established protocols for wound care, opioid withdrawal treatment, and initiation of methadone or buprenorphine. Clinicians should continue to maintain a broad differential for vital sign abnormalities in patients who use drugs.

Administer naloxone (Narcan)! Though naloxone does not inhibit the direct effects of xylazine, the vast majority of opioid (fentanyl or heroin) samples in Philadelphia contain fentanyl, which means Narcan is effective in reversing the respiratory depression associated with opioid overdose. If a person’s respiratory rate and color improves, but they are still drowsy or unconscious, it may be due to the presence of xylazine. Stay with the person to monitor them, call 911, but do not administer more naloxone unless you notice new respiratory depression. 

In our health system, we have limited access to urine confirmation of xylazine exposure. Xylazine can be detected in urine for at least several hours after use; we do not know how long xylazine can be detected in urine after last use or whether xylazine, like fentanyl, accumulates with chronic use. We are actively studying these and other questions with the help of decision-support questions when clinicians order xylazine tests in the University of Pennsylvania health system.

Xylazine test strips, similar to fentanyl test strips, are emerging and could have a role in harm reduction for people who use drugs and want to avoid xylazine exposure. We will post more information as that become available.