Pills seized near Hartland contained the opioid furanylfentanyl but were labelled as Percocet, RCMP said Tuesday.
Health Canada was able to confirm the makeup of the pills through a lab analysis, according an RCMP news release.
Police said they wanted to warn people who are consuming illegal prescription drugs that they can be seriously harmed if the drugs are mislabelled.
Furanylfentanyl is an analog of the deadly opioid fentanyl.
The light blue pills found by the RCMP were about one centimetre in diameter and had the words "Percocet 5" written on them.
Percocet is an analgesic containing a mixture of oxycodone and acetaminophen.
Sgt. J.P. MacDougall of the Woodstock RCMP said the pills are mislabelled to hide the fact they're contraband.
"Because they used that name, people think they know what they are taking," MacDougall said. "We see it fairly commonly."
He said the potency of furanylfentanyl is on a case-by-case basis.
"You never know what you're consuming," he said.
They pills were seized as part of an unrelated investigation, and MacDougall said he couldn't say how many pills there were or their value because the case is before the courts.