What to know about xylazine, the sedative contaminating Philadelphia’s opioid supply

Over the last few years, the animal tranquilizer xylazine has made its way into nearly all of Philadelphia’s “dope” — a catchall term for powders sold as heroin or fentanyl.

For drug users, the effects have been devastating: Xylazine is believed to cause serious, painful wounds and blackouts that don’t respond to naloxone, the opioid overdose-reversing drug. People addicted to xylazine also report intense withdrawals that aren’t eased by traditional opioid withdrawal treatments.

Now, as xylazine turns up in other cities’ drug markets, the problem is gaining national attention, including in a New York Times piece featuring Philly on Saturday. Here’s a primer on Philadelphia’s xylazine problem, and how drug users, advocates, and health officials are trying to address it.

» READ MORE: Xylazine, a dangerous animal sedative, is contaminating Philly’s drug supply

Xylazine is an animal tranquilizer not certified for human use. It has sedative properties, but it’s not an opioid. It’s thought to be used to cut opioids to give them more potency.

Longtime Kensington researcher Philippe Bourgois, now a professor-in-residence in the University of California, Los Angeles’ anthropology department, said he first heard about xylazine being used to cut opioids as early as 2009, from Puerto Rican Philadelphians who told him alarming stories of drugs “back on the island” laced with a horse tranquilizer that caused extreme sedation and intense skin infections.

In the mid-2010s, the synthetic opioid fentanyl began turning up in Philadelphia’s heroin — once known as some of the purest and cheapest in the country. Fentanyl is much more potent than heroin and also easier to make and transport. That makes it more attractive to dealers looking to move more product to earn more money. It is also responsible for the vast majority of fatal overdoses in Philadelphia and around the country.

Many drug users who survived the first wave of fentanyl became tolerant to it — meaning that heroin wasn’t powerful enough to stave off withdrawal, painful episodes of nausea, cramps, and cravings. But fentanyl has a shorter “half-life” than heroin — its effects on the body wear off more quickly, sending drug users into withdrawal earlier. Health officials in Philadelphia believe xylazine may have been first added to fentanyl to give it more “legs” — to prolong a customer’s high.

But the side effects of the xylazine-fentanyl combination, marketed as “tranq dope,” have been catastrophic for drug users in Philadelphia.

» READ MORE: A powerful sedative in Philly’s drug supply is causing severe wounds and agonizing withdrawals. It’s quickly becoming unavoidable.

Xylazine’s sedative effects cause blackouts, drug users report, and overdoses that are difficult to reverse. Naloxone, the opioid-overdose antidote, can revive a person suffering from a fentanyl overdose, for example, but it doesn’t work on xylazine, making a fentanyl-xylazine overdose harder to treat. (Most fatal overdoses in Philadelphia that involve xylazine also involve fentanyl.)

Drug users also report serious wounds developing from xylazine — and not necessarily at the sites of injection, as is more typical with heroin or fentanyl use.

It’s unclear exactly what causes the wounds; it’s possible that xylazine’s effect on the vascular system makes wounds quicker to open and slower to heal. Research on xylazine — which, after all, was never meant for human use — isn’t extensive, which makes harm-reduction measures for xylazine users harder to find.

And while doctors in Philadelphia are experienced at treating opioid withdrawal, the Food and Drug Administration has not approved any drugs specifically for xylazine withdrawal. Fear of severe withdrawal leads many drug users to leave treatment early or not seek it at all, outreach workers say.

Advocates have called for doctors and treatment programs to address xylazine withdrawal among patients in a bid to help them stay in treatment. Last fall, the city health department issued a suggested treatment protocol for xylazine withdrawal that includes drugs to treat high blood pressure, pain, and anxiety.

And while caring for wounds has always been a part of outreach to people with addiction who inject their drugs — who have long been at risk for skin infections at injection sites — outreach groups have stepped up wound care operations in response to the rise of xylazine. Philadelphia officials announced recently that they will use settlement funds from lawsuits against opioid manufacturers to expand the city’s wound care capabilities.

For the last year, the city health department has regularly been testing drug samples through the Horsham-based nonprofit Center for Forensic Science Research and Education, in an effort to better understand the city’s contaminated drug supply.