War on Drugs

Prohibition Gave Us Xylazine in Fentanyl. The Solution, Drug Warriors Say, Is More Prohibition.

The emergence of the animal tranquilizer as an opioid adulterant illustrates once again how the war on drugs makes drug use more dangerous.


The emergence of the animal tranquilizer xylazine as a fentanyl adulterant, like the emergence of fentanyl as a heroin booster and substitute, has prompted law enforcement officials to agitate for new legal restrictions and criminal penalties. That response is fundamentally misguided, because the threat it aims to address is a familiar consequence of prohibition, which creates a black market in which drug composition is highly variable and unpredictable. Instead of recognizing their complicity in maintaining and magnifying that hazard, drug warriors always think the answer is more of the same.

Xylazine was first identified as a drug adulterant in 2006, and today it is especially common in Puerto Rico, Philadelphia, Maryland, and Connecticut. In Philadelphia between 2010 and 2015, according to a 2021 BMJ article, xylazine was detected in less than 2 percent of drug-related deaths involving heroin and/or fentanyl. Its prevalence in such cases had risen to 31 percent by 2019. According to a 2022 Cureus report, "up to 78%" of illicit fentanyl sold in Puerto Rico and Philadelphia contains xylazine. In 2022, the Drug Enforcement Administration (DEA) reports, xylazine was detected in 23 percent of fentanyl powder and 7 percent of fentanyl pills analyzed by its laboratories.

Xylazine is a sedative, analgesic, and muscle relaxant that is not approved for use in humans but is commonly used by veterinarians. It is chemically similar to phenothiazines, tricyclic antidepressants, and clonidine. But like fentanyl and other opioids, xylazine depresses respiration, so combining it with narcotics can increase the risk of a fatal reaction. Unlike a fentanyl overdose, a xylazine overdose cannot be reversed by the opioid antagonist naloxone.

Xylazine also seems to increase the risk of potentially serious skin infections and ulcers that have always been a hazard of unsanitary injection practices. According to a 2022 article in Dermatology World Insights and Inquiries, "the presumed mechanism" is "the direct vasoconstricting effect on local blood vessels and resultant decreased skin perfusion," which impairs healing.

Why is xylazine showing up in fentanyl? For the same reasons fentanyl started showing up in heroin. As a 2014 literature review in Forensic Science International notes, "illicit drugs, such as cocaine and heroin, are often adulterated with other agents to increase bulk and enhance or mimic the illicit drug's effects." Because xylazine and heroin have "some similar pharmacologic effects," the authors say, "synergistic effects may occur in humans when xylazine is use as an adulterant of heroin."

Before the DEA was warning us about xylazine in fentanyl, it was warning us about fentanyl in heroin, and both hazards are the result of laws that the DEA is dedicated to enforcing. From the perspective of drug traffickers, fentanyl has several advantages over heroin. It is much more potent, which makes it easier to smuggle, and it can be produced much more cheaply and inconspicuously, since it does not require the cultivation of opium poppies. Xylazine has some of the same advantages: It is an inexpensive synthetic drug that can be produced without crops. And unlike fentanyl, it is not currently classified as a controlled substance, which makes it easier and less legally risky to obtain.

It is not clear to what extent drug traffickers are relying on domestic sources of xylazine. The DEA "reports finding empty xylazine bottles at U.S. stash houses," Beau Kilmer, co-director of the RAND Drug Policy Research Center, notes in an interview with The New York Times, "so some mixing is happening here." But he adds that we don't know whether "mixing in the U.S. account[s] for the majority or minority of cases."

Either way, American drug users are not clamoring for xylazine in their fentanyl, any more than they were demanding fentanyl instead of heroin. In both cases, the use of adulterants is driven by the economics of the black market. And as usual with illegal drugs, consumers do not know what they are getting. The Times underlines that point by noting one response to the proliferation of xylazine: "Addiction medicine experts," it says, "urged that newly introduced xylazine test strips, which people can use to check the drugs they buy, be as widely distributed as fentanyl test strips."

The fundamental problem, of course, is the dangerous uncertainty created by prohibition. Unlike alcohol, cannabis products sold by state-licensed pot shops, or legally produced, reliably dosed pharmaceuticals, black-market drugs do not come with any assurance of quality or potency. The introduction of new adulterants like xylazine increases that hazard. We have seen this story play out many times before. Whether it is vitamin E acetate in black-market THC vapes, MDMA mixed with synthetic cathinones or butylone, levamisole in cocaine, or fentanyl pressed into ersatz pain pills, prohibition reliably makes drug use more dangerous.

The solution, according to drug warriors alarmed by xylazine in fentanyl, is more prohibition. "Law enforcement agents are pressing for xylazine to be listed as a controlled substance, which would criminalize distribution for human use," the Times notes.

That proposal has raised alarm among veterinarians, who understandably worry that such a designation would interfere with the legitimate use of xylazine. But such concerns did not stop legislators and regulators from restricting the use of prescription pain relievers in response to the "opioid crisis," with predictably disastrous consequences.

That crackdown succeeded in the sense that it reduced opioid prescriptions. But it simultaneously deprived patients of the medication they needed to control their pain and pushed nonmedical users toward black-market substitutes that are far more dangerous. The prohibition-driven rise of illicit fentanyl, meanwhile, made those drugs even more of a crap shoot. The result was predictable: Drug-related deaths not only continued to rise; they rose at an accelerated rate, reaching record levels in recent years.

"As federal and state agencies imposed strict controls on prescription opioids," the Times notes, "drug dealers and people who use drugs shifted to using illegal opioids—heroin, counterfeit pills and illicit fentanyl." But the Times does not mention the resulting increase in drug-related deaths or the impact on pain patients.

The latter omission is especially striking in an article that is highly sympathetic to veterinarians worried about potential restrictions on xylazine. You might think that the suffering of humans who cannot get adequate pain treatment would be worthy of a mention in a story that devotes several paragraphs to a horse undergoing dental surgery.

Still, the Times is appropriately skeptical of the idea that expanding the war on drugs to include xylazine would be an effective way to address the hazards it poses as a fentanyl adulterant. It is "unclear what impact scheduling would actually have on human consumption and health," the paper says, citing Kilmer. The Times also cites Maritza Perez Medina, federal affairs director at the Drug Policy Alliance, who is "worried that criminalizing xylazine would not substantially address its problems."

Perez Medina notes the perennial challenge confronting drug warriors who reflexively respond to the problems they created by doubling down on a strategy that has failed for more than a century. "Crackdowns put us in a game of whack-a-mole," she says. "When we try to eradicate one drug, a new one comes up." It is a lesson that prohibitionists never seem to learn.