London, Ont., police warned of a “potentially toxic supply of illegal substances” distributed in the downtown core on March 11, and emergency services there responded to 39 overdose calls in 24 hours, they said.
It appears it was a new, deadly concoction that naloxone, used to combat potentially deadly opioid overdoses, fails to counter.
Hayley Thompson is the project manager at Toronto’s Drug Checking Service. She analyzes drug samples and informs users and the greater community on what is currently laced in the drugs on the illegal “unregulated” market.
Thompson said the main non-opioid drugs cut into the fentanyl supply currently are veterinary tranquillizers, medetomidine and benzodiazepines, which do not respond to naloxone.
Matt Johnson, a supervisor at the Overdose Prevention Site at Street Health Toronto, said in the early days of fentanyl, overdoses would escalate quickly, and people would recover quickly.
They said that after administering naloxone, the most common brand of which is Narcan, people would be back to normal within about 10 to 15 minutes.
Johnson said there is no antidote to the new mixture and all they have to offer is oxygen and time.
People are out for hours when overdosing on tranquillizers, they said, and sites like theirs are not set up for long-term monitoring.
Johnson said that tranquillizers slow breathing and the person’s pulse.
“We aren’t and never will be set up to deal with cardiac issues. And so, when we get those low pulse rates, we have to call 911. So, we’ve been relying on 911 a lot more,” they said.
The withdrawal effects of tranquillizers are severe, Johnson said, the main concern being dramatically increased blood pressure.
They said their first case of naloxone not reviving a client was in 2019, and it was not until late 2025 or early 2026 that they started seeing animal tranquillizers in most of the drug supply. Johnson said that as of late February into early March, benzodiazepines, which had been missing from the drug supply for a while, had been reintroduced.
They said “benzos” compounded with medetomidine greatly increase the odds of complications in overdoses.
“Most overdoses are showing signs of veterinary tranquillizers for sure, and so it’s made our overdose response more complicated,” Johnson said.
They said they find it unfair to be the messengers telling their clients that defunding will cut lifesaving services and that no alternative is being offered.
Barbara Fornssler, an assistant professor at the School of Public Health at the University of Saskatchewan, said criminalizing substances often creates a more harmful, unregulated market.
She said the demand for substances does not go down when “we crack down on the unregulated market.”
Fornssler said she fully believes recovery is possible for severe drug addicts. Fornssler said there are many possible supports which have proven effective.
“You can absolutely recover physiologically and emotionally and socially from even what we would classify as the most deeply dependent,” she said. With the stipulation of having access to necessary supports, Fornssler said.
“You know, if somebody doesn't have a safe place to sleep at night, it's really hard to stop using a stimulant that might keep you up overnight so you can keep yourself safe, right?” she said.
Fornssler said she hopes her students are empathetic to drug users and understand that drug abuse is a public health issue, not a criminal issue.
“It’s the war on drugs that brought us here, and the war on drugs will not get us out of it,” she said.
