The Waterloo Region Integrated Drugs Strategy (WRIDS) didn’t say where in the province the substance was seized but said the product has not been found in the region.
A similar substance was also seized in Ohio that contained heroin and fentanyl, WRIDS said.
Carfentanil is said to be 100 times more potent than morphine and, like fentanyl, it cannot be detected by sight, smell or taste.
WRIDS is urging drug users to take every precaution, including carrying naloxone and never using alone.
Information on where residents can get a free naloxone kit can be found online.