Xylazine is a powerful sedative approved only for use in animals that has become a dangerous adulterant in the illegal drug supply. It works by blocking the release of key brain chemicals, producing heavy sedation, slowed breathing, a drop in blood pressure, and muscle relaxation. In humans, it also causes severe skin wounds that resist healing, and its effects cannot be reversed by naloxone, the standard overdose rescue medication.
How Xylazine Works in the Body
Xylazine activates a specific type of receptor in the nervous system called alpha-2 adrenergic receptors. When these receptors are triggered, the brain releases less norepinephrine and dopamine, two chemicals responsible for alertness, heart rate, and blood pressure. The result is deep sedation, pain relief, and significant muscle relaxation. In animals, these effects are precisely what veterinarians need: a way to calm a frightened horse or injured cow long enough to treat it safely.
In humans, the same mechanism produces dangerously exaggerated effects. Blood pressure drops (hypotension), heart rate slows (bradycardia), breathing becomes shallow, and the person may lose consciousness or experience amnesia. Because xylazine is not an opioid, it acts through an entirely different pathway than drugs like fentanyl or heroin. This distinction matters enormously in an overdose situation.
Why It’s Showing Up in Street Drugs
The FDA approved xylazine in 1972 for veterinary use, primarily in horses, cattle, and deer. It was never approved for humans. But over the past several years, xylazine has been increasingly mixed into illicit fentanyl, likely because it extends and deepens the sedative effect at low cost. In 2024, 36 percent of fentanyl powder samples and nearly 6 percent of fentanyl pills tested positive for xylazine.
The consequences have been severe. Xylazine was detected in 3.7 percent of overdose deaths in 2020. By 2022, that figure had risen to 6.6 percent. Across 21 jurisdictions tracked by federal agencies, xylazine-involved deaths increased 276 percent between January 2019 and June 2022. In April 2023, the White House formally designated fentanyl mixed with xylazine as an “emerging drug threat,” a classification that triggered a coordinated federal response plan. Despite this, xylazine is still not a controlled substance under federal law, though regulators have been evaluating whether to schedule it while preserving veterinary access.
Skin Wounds and Tissue Damage
One of xylazine’s most distinctive and alarming effects in humans is the development of severe, non-healing skin ulcers. These wounds can appear at injection sites but also on parts of the body far from where the drug was injected, suggesting a systemic effect rather than just local tissue damage.
The mechanism appears to involve xylazine’s constriction of small blood vessels. When blood flow to the skin drops, tissue doesn’t get enough oxygen and nutrients to survive or repair itself. People who use xylazine repeatedly describe wounds that begin as pale, discolored patches of skin, then gradually open into ulcers that produce foul-smelling yellow drainage. These wounds often become infected, spreading redness and warmth to the surrounding area. In documented cases, patients have presented with multiple ulcerations across both forearms and knees, some with necrotic (dead tissue) centers reaching 4 centimeters in diameter. The combination of reduced blood flow, repeated injection trauma, and impaired healing creates a cycle of worsening tissue destruction that can, in the most severe cases, require amputation.
Why Naloxone Alone Isn’t Enough
Naloxone, the medication carried by first responders and available at pharmacies, works by blocking opioid receptors. It is highly effective at reversing heroin or fentanyl overdoses. But xylazine is not an opioid. It acts on a completely different set of receptors, so naloxone has no direct effect on it.
This does not mean naloxone should be skipped. Because xylazine is almost always mixed with fentanyl or other opioids, naloxone can still reverse the opioid component of an overdose and partially restore breathing. The problem is that xylazine’s effects on breathing and consciousness will persist even after naloxone is administered. The CDC recommends that anyone responding to a suspected overdose should give naloxone, call 911, and provide rescue breaths, since xylazine slows breathing in a way that continues after the opioid effects are addressed. Rescue breaths (one breath every five seconds after an initial two slow breaths) are considered especially important in xylazine-involved overdoses. Rolling the person onto their side into the recovery position is also recommended while waiting for emergency medical services.
First responders are advised to consider xylazine involvement any time naloxone does not produce the expected response. A person who remains unresponsive or continues to breathe very slowly after receiving naloxone may have xylazine in their system.
Withdrawal and Physical Dependence
Xylazine produces its own pattern of physical dependence separate from opioid withdrawal. People who use xylazine regularly and then stop can experience withdrawal symptoms that standard opioid withdrawal medications don’t fully address. In one documented hospital case, a patient’s xylazine withdrawal required treatment with a combination of medications that act on the same type of receptor xylazine targets, essentially tapering the body off the drug’s effects gradually. By hospital day 4, the acute withdrawal symptoms had resolved, though the full hospital stay lasted 19 days as clinicians managed overlapping opioid dependence as well.
The fact that xylazine withdrawal exists independently of opioid withdrawal complicates treatment. Someone trying to stop using fentanyl laced with xylazine faces two separate withdrawal processes at once, each requiring different approaches. This is one of the reasons xylazine-adulterated fentanyl has been particularly difficult for addiction treatment programs to manage.
How People Are Exposed
Most people who encounter xylazine do not choose to take it. It enters the body as an unannounced additive in fentanyl or other street drugs. People buying what they believe is fentanyl, heroin, or pressed pills may have no idea xylazine is present. Drug checking services, including fentanyl test strips, do not detect xylazine, though xylazine-specific test strips have become available in some areas.
The drug can be injected, snorted, or swallowed, and its sedative effects appear regardless of the route. However, the severe skin wounds are most closely associated with injection use, where the combination of direct tissue exposure and repeated needle trauma accelerates damage.