A wave of drug overdoses in Waterloo Region has prompted a warning from health officials.

According to the Waterloo Region Integrated Drugs Strategy (WRIDS) group, six overdoses have been reported in Kitchener and Cambridge this week.

Heroin is suspected in five of those cases, and Fentanyl in the sixth, although toxicology reports have not yet come in.

WRIDS co-ordinator Paul A. Gregory says he’s concerned about bootleg Fentanyl showing up on the region’s streets.

Fentanyl is a potent prescription painkiller, which can be mixed with heroin, cocaine, crystal meth or other substances to produce a more powerful recreational narcotic.

Authorities say that anyone using drugs should exercise “extreme caution” to prevent potential overdoses, and never use drugs while alone or without knowing what they are.