Xylazine
Drugs of abuse
Drugs of abuse
A veterinary sedative («tranq») mixed into illicit fentanyl and heroin. An alpha-2 agonist, not an opioid: naloxone does not reverse it, and it causes wounds.
Also called: Tranq, Tranq dope (mixed with fentanyl)
Quick facts
- Group
- Drugs of abuse
- Target
- Central alpha-2 adrenergic receptors (like clonidine)
- Used for
- No approved use in humans · Clinical relevance
- Key effects
- Deep sedation · Bradycardia and hypotension
- Monitor
- Breathing · Heart rate · Wounds
No doses: the clinician sets them by the current guideline.
Mechanism of action
The figure shows dexmedetomidine, another alpha-2 agonist used in people, bound to the human alpha-2A receptor; no structure with xylazine on this receptor is available.
Xylazine was approved in 1972 as a sedative and analgesic for animals only. Like clonidine, it activates alpha-2 adrenergic receptors in the brainstem, which rapidly cuts the release of noradrenaline and dopamine in the brain. The result is sedation, slow breathing, bradycardia and hypotension. It may bind other brain receptors too. Because it is not an opioid, naloxone does not reverse its effects, although naloxone is still given since opioids are usually present.
- Xylazine activates brainstem alpha-2 receptors
- Noradrenaline and dopamine release falls
- Sedation, slow breathing, bradycardia, hypotension
- Naloxone reverses the opioid, not the xylazine
Indications
- No approved use in humans; veterinary sedative and analgesic only
- Clinical relevance: opioid overdoses that respond poorly to naloxone, and chronic necrotic wounds in people who inject drugs Opioid overdose →
Adverse effects
Common
- Deep sedation
- Bradycardia and hypotension
- Hypothermia and miosis
- High blood glucose
Contraindications
- Not approved for any human use
- Veterinary reversal agents (yohimbine, tolazoline) are not used in humans
Key interactions
- Fentanyl, heroin and other opioids
- Deeper sedation and respiratory depression; mixed overdoses
- Naloxone
- Reverses the opioid part only; the patient may stay sedated
- Benzodiazepines, alcohol and other sedatives
- Additive CNS and respiratory depression
What is monitored
- Breathing, oxygen saturation and level of consciousness after naloxone
- Heart rate, blood pressure, temperature and glucose
- Wounds: size, infection, need for surgical care
- Withdrawal signs during treatment for opioid use disorder
Pregnancy and breastfeeding
No human safety data; it is found with opioids, whose use in pregnancy causes neonatal withdrawal and other harms.
Nursing care
- Give naloxone for any suspected opioid overdose and support breathing with ventilation
- Expect persistent sedation after naloxone; keep monitoring
- Remember xylazine is not found by routine toxicology screens
- Provide early wound care and teach the patient to seek care for wounds
- Watch for withdrawal not explained by opioids
Pharmacokinetics
- Absorption
- Usually injected with opioids; also smoked, snorted or swallowed
- Elimination
- Cleared quickly, which makes it hard to detect
- Half-life
- Short (about 23 to 50 minutes)
Test yourself
Think of the answer, then tap the question to see it.
What is xylazine's mechanism of action?
It is a central alpha-2 adrenergic agonist, like clonidine, which lowers noradrenaline and dopamine release.
Should naloxone be given when xylazine is suspected?
Yes; it does not reverse xylazine, but opioids are usually present too, and breathing support is added.
Which skin finding suggests repeated xylazine exposure?
Severe necrotic ulcers, which may appear away from the injection sites.
Connections
← Back to the class: Drugs of abuse
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: FDA warns about the risk of xylazine exposure in humans (U.S. Food and Drug Administration, 2022); Xylazine (National Institute on Drug Abuse (NIDA), 2026).
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Representative model, for educational purposes only.