Animal tranquilizer medetomidine increasingly found in Calgary's fentanyl supply

A powerful animal tranquilizer is increasingly turning up in Calgary's illicit fentanyl supply, raising alarm among doctors and harm-reduction workers about overdose risk and treatment effectiveness.

Medetomidine, which intensifies fentanyl's effects, was first detected in Calgary in October 2025 and has become far more prevalent since then. The substance has been turning up in wastewater tracking and other sampling conducted by researchers monitoring street drugs in the city.

Dr. Monty Ghosh, a University of Calgary researcher who closely tracks usage patterns, said the mixture is particularly dangerous because it erodes the ability of naloxone to reverse overdoses. "With the application of naloxone, that medetomidine piece is still there, you have to let it dissipate on its own," he said. "It's much more prevalent than it was before…that could increase (the number of) deaths and we're seeing patients with bad withdrawals."

Those withdrawals are marked by dangerous reactions such as skyrocketing blood pressure.

The threat coincides with the June 30 closure of the supervised consumption component at the Sheldon M. Chumir Health Centre, which had been operating for nearly a decade. Replacing it is a Recovery Response Team based at the facility, operating 24/7 and offering withdrawal management and recovery supports.

Ghosh expressed concern about the timing. "It's still too early to say from a medical perspective what the impact of the closure is but because the drug supply is always shifting, we could see a spike of overdoses," he said. "Was the Chumir site perfect? No, but instead of closing it maybe find a different way."

Cecilia Fraser, who helps run an outreach program for the city's vulnerable population, echoed that concern. "The supply of opioids is getting more dangerous, naloxone doesn't do anything and without that physical space to go to, people are back to going to the alleys and parks," she said. "With the closure of the site, we're kind of playing it by ear."

Fraser also noted that the end of free access to drug paraphernalia will likely lead to more communicable diseases and deaths. "People are fashioning pipes out of whatever they can find," she said.