Not yet medically reviewed, information on this site is in preparation and has not been verified by a medical reviewer.
Drug index / Depressant / Xylazine
Depressant

Xylazine

Xylazine ("tranq") is a veterinary sedative not approved for human use that has become a widespread adulterant in the illicit fentanyl supply. It is not an opioid and is not reversed by naloxone, and it causes severe, distinctive skin wounds that can lead to amputation. It is central to the question of what street drugs are cut with.

Pending medical review. This page has not yet been checked by a clinician, so read it as general information, not medical advice.

Overview

Xylazine, known on the street as "tranq" or "tranq dope," is a sedative and muscle relaxant approved only for veterinary use (in animals such as horses and cattle) and never approved for humans — early human trials in the 1960s were abandoned because it caused dangerous drops in blood pressure and severe CNS depression. In recent years it has spread rapidly through the illicit drug supply as an adulterant, most often mixed into fentanyl. It is now one of the most common substances found cutting street fentanyl, which means many people are exposed to it without knowing. It matters here less as a drug people seek out than as a hidden contaminant of the opioid supply.

Source: peer-reviewed literature; DEA; CDC

Chemistry & mechanism of action

Xylazine is an alpha-2 adrenergic receptor agonist. By stimulating these receptors it reduces the release of certain neurotransmitters, producing sedation, muscle relaxation, and pain relief, along with slowed heart rate and lowered blood pressure. Crucially, it is not an opioid and does not act on opioid receptors — which is why the opioid-overdose antidote naloxone does not reverse xylazine's effects. When xylazine is mixed with fentanyl, naloxone can reverse the fentanyl but leaves the xylazine-driven sedation and breathing suppression untouched.

Source: peer-reviewed pharmacology literature

Effects

In people, xylazine produces heavy sedation, drowsiness, and a prolonged "blackout" state that can last for hours, along with slowed breathing, slowed heart rate, and low blood pressure. Because it is usually encountered mixed with fentanyl, its effects overlap with and prolong the opioid's sedation, which is part of why it has been adopted in the supply. People often have no idea they have taken it.

Source: peer-reviewed literature

Risks & harms

Xylazine adds two serious dangers on top of the opioids it is mixed with. First, because it is not an opioid, naloxone will not reverse its sedation or the breathing suppression it contributes — so an overdose involving xylazine may not fully respond to naloxone, though naloxone should still always be given for a suspected opioid overdose because fentanyl is usually present. Second, xylazine causes severe, distinctive skin wounds: open, necrotic ulcers that can appear anywhere on the body, not only at injection sites, are thought to result from the drug constricting blood vessels and starving tissue of blood, and in serious cases can become infected or lead to amputation. Repeated use also produces dependence and a difficult withdrawal. Xylazine test strips exist and can detect its presence in a drug sample. Because it is a hidden adulterant, the core risk is that people are exposed to all of this without knowing xylazine is there.

Source: peer-reviewed literature; DEA; CDC

Harmful effects

deepens sedation/respiratory depression when mixed with fentanyl; associated with severe skin wounds; NOT an opioid → naloxone does NOT reverse xylazine's effects)

Medicinal use

FDA-authorized veterinary use only

History

emerging illicit adulterant; seized in xylazine-fentanyl mixtures in 48/50 states + DC

Prevalence

growing presence in illicit fentanyl supply

Images

Visual references coming soon.

If it’s too intense

If an experience becomes overwhelming, the goal is to stay safe and let it pass, most difficult experiences ease as the drug wears off.

  • Get to a calm, safe space with someone you trust who is sober and can stay with you.
  • Cool down if you’re overheating, move somewhere cool, remove extra layers, rest. Overheating is especially a risk with stimulants and MDMA.
  • Sip water to thirst, but don’t over-hydrate. Drinking large amounts of plain water (especially after MDMA) can dangerously dilute your blood sodium (hyponatremia). Electrolytes help more than volume.
  • Slow your breathing, long, slow exhales help settle a racing heart and anxiety.
  • A sugary drink, fruit juice, or a snack can ease shakiness and the anxiety that comes with low blood sugar.
  • Do not take more, and do not add another substance to manage it. Redosing or adding something else (including a sedative like a benzodiazepine) can make things worse, not better.

With depressants, the danger is over-sedation: if someone is very drowsy, hard to wake, or breathing slowly, treat it as an emergency.

Call 911 (or Poison Control, 1-800-222-1222) right away for chest pain, a very high body temperature, a seizure, unconsciousness, or severe confusion. These are medical emergencies, not something to wait out.

Source: general harm-reduction guidance from SAMHSA, NIH/NIDA, and MedlinePlus, in our own words. Draft, not yet medically reviewed.

Dosage

Pending medical reviewer

Sources

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