Medetomidine is a powerful non-opioid sedative and anesthetic used in veterinary medicine similar to Xylazine. It is licensed for use by veterinarians to calm and provide pain relief during procedures in animals such as dogs and cats. It acts on the central nervous system by stimulating alpha-2 adrenergic receptors, causing sedation, muscle relaxation, and lowered heart rate and blood pressure.
Medetomidine is not approved for human use.
How is medetomidine used?
Although only used legitimately in animals, medetomidine has been detected as an adulterant in street drugs, such as heroin and fentanyl. Essex police reported the presence of medetomidine in heroin seized in June 2025 and Public Health Scotland’s Rapid Action Drug Alerts and Response (RADAR) system recently warned that medetomidine, has been detected in drugs sold as benzodiazepine.
Effects and risks
When combined with heroin and fentanyl, medetomidine is thought to boost and/or extend the effects of these drugs in a way that is similar to Xylazine but even more powerful and longer lasting.
Short term effects include:
- Intense sedation or sleepiness
- Very slow heart rate (bradycardia)
- Low blood pressure (hypotension)
- Difficulty breathing or respiratory depression
- Confusion, hallucinations, stupor
- Prolonged unconsciousness that may last hours
There is also risk of fatal overdose, medetomidine is very potent and can dangerously depress breathing and circulation, especially when combined with opioids or other depressants.
Updated February 2026