Law enforcement agencies nationwide are warning of the growing threat of the sedative drug xylazine, also known as “tranq” or the “zombie drug,” that is increasingly being found laced into opioids like fentanyl.

Xylazine, a veterinarian tranquilizer, has permeated the illicit drug trade, and is associated with severe health risks and complications — including bacterial flesh-eating disease.

The drug can cause extreme sedation, leading to unconsciousness and immobility, and is not responsive to naloxone, the drug that is used to reverse opioid overdoses.

Additionally, xylazine has been linked to the development of lingering sores that can lead to serious infections, amputations and even death if left untreated.

The Biden administration recently declared tranq an “emerging drug threat,” prompting a national response involving expanded health interventions, research, data collection and crackdowns on suppliers.

The Food and Drug Administration (FDA) also issued an alert warning health care professionals about xylazine.

In addition, law enforcement has been tasked with cracking down on the drug, which has proved difficult due to the lack of regulations surrounding it. Part of the issue is that the drug can be legally purchased on the market, but is illegally repurposed in fentanyl preparations.

In New Jersey, xylazine is most commonly found in Camden, having migrated there from Philadelphia. According to New Jersey State Police Captain Jason Piotrowski, the presence of tranq in the illegal drug market is ubiquitous, with approximately 30% of opioid samples in the state having been found to contain xylazine. The drug has also been implicated in 7% of overdose fatalities in the state.

“We’ve been tracking it for a long time,” Piotrowski said. “There’s a lot of confusion right now, and I’m not sure anyone has a really good handle on it yet.”

To illustrate how widespread xylazine is, the New York Times referenced a study published in June last year that detected xylazine in the drug supply in 36 states and the District of Columbia.

Up to 25% of drug samples from New York City tested positive for the drug.

Despite the worrisome figures, experts say that fentanyl remains the primary cause of overdose deaths, and experts emphasize that xylazine plays a secondary role in most cases.

“There’s nothing more dangerous about tranq, really, than fentanyl,” said Dr. Lewis Nelson, chair of Rutgers University’s Department of Emergency Medicine. “The 800-pound gorilla here is the fentanyl. Even though people die with xylazine in their bodies, it has very little to do with the reason they die. It’s fentanyl, or the analogs of fentanyl, that’s the culprit in the vast amount of cases. Xylazine is, I wouldn’t quite say an innocent bystander, but it’s a bystander.”

Efforts to address the issue are ongoing, with legislation being introduced around the country to tighten oversight of veterinary medications, including xylazine, and classify it as a controlled dangerous substance.

“There’s such a national spotlight on it right now, on both sides of the aisle,” New Jersey Assemblyman Kevin Rooney told the New Jersey Monitor. “We have to be on the side of protecting lives and helping our law enforcement. And this is the reason that these bills were created, to do that.”

Harm reduction workers are providing wound-care supplies to individuals affected by xylazine, with some advocating for the distribution of test strips to detect the presence of xylazine in drugs.

Still, opinions differ on the effectiveness of test strips, with some experts expressing concerns about their limitations.

“There could be one speck of fentanyl in there, or the whole thing could be fentanyl. You have no idea,” Nelson said. “So what do you do with that information? Do you really believe in your heart of hearts that somebody says: ‘Oh, there’s fentanyl in my heroin, so I’m gonna throw it out and go buy some more?”

Law enforcement agencies have also begun implementing programs to track xylazine in confiscated drugs to gain a better understanding of its presence and combat its deadly effects.

In Los Angeles, where xylazine has become a significant problem, the L.A. County Sheriff’s Department has started a similar program to track the drug.

Meanwhile, health care and addiction experts say they are overwhelmed with cases. Bill Bodner, a DEA special agent based in L.A., spoke about the drug’s dangerous side effects. “It’s really gruesomely disfiguring people,” he said. It’s much more likely to stop someone from breathing and the things that come along with xylazine, it’s a vasoconstrictor. So when you’re injecting it, it’s actually reducing the blood circulation.”

In New York City, xylazine has spread rapidly among the homeless population, often being mixed into other street drugs.

Experts say the drug’s low cost and profitability for dealers contribute to its prevalence.

Xylazine presents an additional challenge for health care workers and emergency services as it cannot be reversed with naloxone.

“Xylazine is a huge problem for the entire country,” said Frank Tarentino, head of the Drug Enforcement Administration’s New York Division. “Fentanyl is the deadliest drug we have ever faced. When you add xylazine, it becomes even deadlier.”

New York City Special Narcotics Prosecutor Bridget Brennan noted that overdoses have routinely been linked to xylazine-laced fentanyl pills. “It’s become increasingly prevalent in fatal overdoses in New York City and it’s always found with fentanyl,” Brennan told The New York Post, adding that most of the drugs enter the U.S. from across the southern border after being manufactured in Mexico.

“The American public has no idea what they are getting when they buy street drugs. The percentage of street drugs that have fentanyl is extremely high, and the percentage of xylazine is growing,” Tarentino added.

According to the DEA, the rise of tranq coincides with one of the largest hauls of illegal fentanyl in a single year in the state’s history, with the agency confiscating 72 million lethal doses of fentanyl last year.