03 Aug 2026
Surrey Substance Use Partnership's Local Drug Information System have received intelligence that Medetomidine, a potent non-opioid veterinary sedative, has contaminated the drug supply in Sutton, South West London.
Medetomidine is a veterinary anaesthetic and sedative similar to Xylazine. It has recently emerged as an illicit drug adulterant, particularly in mixtures containing synthetic opioids like Fentanyl. These combinations, sometimes referred to as “tranq”, greatly increase sedative effects and overdose risk.
Research from Durham University (May 2025) found that in Philadelphia, Medetomidine was present in 87% of fentanyl samples just six months after first being detected. Medetomidine is believed to enhance the euphoric effects of opioids, but it is even more potent and longer-lasting than Xylazine.
Overdose or exposure to Medetomidine can cause:
Extreme sleepiness or unresponsiveness.
Very low blood pressure.
Slow heart rate.
Breathing difficulties or respiratory failure.
Coma or death.
Medetomidine depresses the central nervous system and slows the heart rate. When used with opioids, these effects are intensified, greatly increasing the risk of fatal overdose.
Medetomidine is not an opioid, so naloxone will not reverse its effects. However, because it is often mixed with opioids, naloxone should still be administered in a suspected overdose, as it can reverse the opioid component and may still save a life.
Share this alert with those who might use similar substances or work with those who do, and encourage them to seek help and advice.
Ensure those who need to be are aware of the signs of overdose and the appropriate emergency response, including the use of naloxone where indicated. Report any unusual drug-related presentations or adverse reactions through local reporting channels. Stay alert and share this information.
Raising awareness can prevent harm and save lives.
