Medetomidine Found in Illicit Drugs in Scotland, Raising Safety Concerns

Medetomidine, patented in 1981 and introduced to Europe in 1987 under the name Domitor, is often referred to incorrectly as a "rhino tranq." This term is misleading, as there is no substantial evidence to suggest it is used to sedate rhinos. Actual rhino tranquilizers, like etorphine, are significantly more potent than medetomidine.

The substance is closely related to xylazine, another veterinary sedative found in illicit drugs in the US and UK. Both substances act on similar receptors and can constrict blood vessels, raising concerns about potential severe skin wounds associated with xylazine. However, such wounds have not been consistently reported in cases involving medetomidine.

Unlike opioids, medetomidine decreases activity in the locus coeruleus, a part of the brain responsible for wakefulness, while opioids may suppress the body's breathing control. The simultaneous use of both can lead to multiple dangerous effects.

Medetomidine's potency is another significant concern; just a hundredth of the usual dose can produce similar effects as larger doses, making even minuscule amounts hazardous. The substance can lead to elevated blood pressure and a slow heart rate, which may later be followed by a sharp decline in blood pressure.

In the US, the situation is more alarming; estimates suggest that about 83% of fentanyl samples tested in Philadelphia between 2024 and 2025 contained medetomidine.

While opioid overdoses can generally be reversed with naloxone, there is no equivalent treatment for medetomidine overdose in humans. Veterinary medicine offers atipamezole, which counteracts medetomidine in animals, but rapid reversal in humans can cause severe withdrawal symptoms such as vomiting, accelerated heart rate, and increased blood pressure.

The origins of medetomidine's presence in illicit drugs remain unclear, unlike xylazine, which is believed to originate mainly from China. In the US, its illegal presence may stem from diversion of veterinary supplies or unauthorized production.

To address this issue, harm-reduction strategies such as safe drug consumption spaces could be beneficial. In Scotland, Glasgow operates The Thistle, a facility where people can use drugs under medical supervision. Expanding such facilities is essential.

Currently, there are no specific test strips for medetomidine, unlike those available for xylazine. Laboratory testing of blood or urine remains the only reliable method to confirm the presence of medetomidine, which is vital for ensuring appropriate treatment following an overdose.

Awareness is crucial for drug users as well as emergency responders, including police and ambulance services, who need to be educated about the potential risks associated with medetomidine.

In October 2025, the UK's Advisory Council on the Misuse of Drugs made recommendations to classify medetomidine as a class C drug, train emergency responders regarding its effects, improve public information resources, and enhance border-control testing for drug seizures. The government has yet to respond to these recommendations.