The Renfrew County and District Health Unit is raising concerns over the illegal use of fentanyl.

The health unit is concerned that the normally regulated opioid could be sold with other drugs mixed into it.

It says even a small amount of fentanyl can be fatal and buying the drug off the street means it could be much more potent than if it were prescribed.

Naloxone is a drug which temporarily combats the effects of an opioid overdose and is available for free from any local health unit office, addiction treatment centres and some local pharmacies.

More information on fentanyl, risk management and addiction services can be found here.