The first "Tranq" drug death in Santa Clara County has been confirmed by the medical examiner-coroner's office, officials said Monday.

Tranq is the street name for xylazine, a veterinary tranquilizer with no approved use in humans. It is increasingly found in drug supplies across the country, leading to deadly overdoses and serious injuries, according to federal officials.

The fatality in San Jose was a 36-year-old man who was found unresponsive in late February; postmortem toxicology found he had drugs including xylazine and fentanyl in his system. Xylazine is often added to fentanyl without users’ knowledge to extend the opioid’s euphoric effects, the coroner's office said in a press release.

“This tragic event is an important alert to the community that xylazine is now present in drugs in Santa Clara County,” said Dr. Michelle Jorden, Santa Clara County's medical examiner-coroner. “The last thing I want is to see more deaths due to xylazine here, but sadly, the experience of the rest of the country indicates there may be more to come.”

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Reports from the federal Drug Enforcement Administration indicate that xylazine is often mixed with opioids like fentanyl and heroin. Although xylazine overdose is not reversed by naloxone (Narcan), medical experts say the life-saving medication still should be administered to reverse the opioid component of the overdose. Naloxone would not harm someone under the influence of xylazine, experts say.

“Community members need to be even more vigilant with how and what they are using, with xylazine now in Santa Clara County,” said Dr. Tiffany Ho, medical director of the county's Behavioral Health Services Department. “It is critical to still administer naloxone and call 911 when encountering someone with an overdose, since xylazine is often mixed with opioids for which naloxone could still make a life-and-death difference.”

Elsewhere, San Francisco's health department is stocking up on tools to detect xylazine, which causes severe skin disease in its users.

At least four people have died in San Francisco from xylazine between mid-December 2022 and mid-January 2023, according to the Medical Examiner's Office.