Ottawa Public Health officials say Fentanyl patches, altered and used illicitly, are behind several recent overdoses in the city. (Tom Gannam/Associated Press)

Public health officials said a prescription skin patch is growing in popularity amongst illicit drug users, and has caused a spate of recent overdoses in Ottawa.

Fentanyl is a potent drug, similar to morphine and stronger than OxyContin, and is used to treat chronic pain. Drug abusers have been cutting the prescription patches into four pieces, cooking them down in small silver drug pots, and injecting them.

The results have been fatal, Ottawa Public Health nurse Pamela Oickle said, when users don't know how much of the drug they're getting.

"It's of grave concern to us. We've had a number of overdose deaths due to Fentanyl patch use," said Oickle.

A health team is trying to quantify overdoses and determine how widely Fentanyl is used in the city, Oickle said, but for now nurses are turning to drug users to figure out how much of the drug people are taking.

"There is no research to determine 'OK how much is a safe amount'...how much will put you into an overdose," Oickle said.

"So we have to rely on our clients for that information."

Rob Boyd is director of the Sandy Hill Community Health Centre, one of Ottawa's needle exchange programs where drug users can access clean syringes. He said Fentanyl's popularity is rising at an alarming rate.

"This is certainly much more of a dangerous drug out in the community," Boyd said.

"It's about 80 times more potent than an (OxyContin)."

Boyd said the problem with Fentanyl is that the drug isn't evenly distributed across the patch. One section of a Fentanyl patch, cooked down, may not produce the desired high, so many users take more.

"They're not getting that effect right away like with other opiates, and they do another injection and all of a sudden they have too much on board and that's when they overdose," Boyd said.