Oct 26, 2017

What is it?

Originally developed in 1974 and manufactured as Wildnil, a tranquilizer for large animals, carfentanil is a synthetic opioid produced from morphine. Not suitable or intended for human use, Carfentanil is 1,000 times more potent than morphine and 100 times more potent than fentanyl.1

Carfentanil is used to enhance the potency of other drugs like heroin and fentanyl, but as it is colourless and odorless and appears in such small quantities, it is nearly impossible to detect.

An amount of carfentanil the size of a granule of salt is enough to prove fatal for human consumption.

“It’s one of the most frightening drugs I can imagine in circulation. It’s only a matter of time before it is detected in every province in Canada.”

– Dr. David Juurlink, Head of Clinical Pharmacology and Toxicology, Sunnybrook Health Sciences Centre2

Why is it so dangerous?

Carfentanil rapidly binds to opioid receptors in the brain, and within minutes, leads to overdose symptoms like sudden drowsiness, slowed or depressed breathing, disorientation, sedation, pinpoint pupils, and clammy skin. Without immediate intervention (including a dose of naloxone to reverse opioid effects), carfentanil can be fatal. While carfentanil by itself is unlikely to cause addiction, its presence in more ubiquitous drugs like heroin and fentanyl exposes unsuspecting users to its lethal risks.3

“[It is estimated that] fentanyl and carfentanil will kill at least 2,000 people in a year, and that the number will only go up without drastic action.”

Dr. David Juurlink

Is Carfentanil in Canada?

After being detected in US street drugs in July of 2016, carfentanil quickly became a grave concern for law enforcement as well as health professionals. Since then, it has made its way north. Street drugs seized in Ontario last December tested positive for carfentanil for the first time,4 and this October, 42 kilograms of carfentanil were found in the home of a 33 year old Oshawa man5. Canada is currently facing an opioid crisis, with at least 2,458 Canadians deaths from opioid-related overdoses in 2016.6


How did carfentanil become such a risk?

In the early 2000s, opioids such as morphine, OxyContin, and fentanyl were regularly prescribed for pain treatment because they weren’t thought to be greatly addictive. That perception changed only a few years later when it became clear that these drugs were highly addictive, but by then millions of pills had already been sold which led to higher rates of experimentation outside of prescription use and subsequently, multitudes of addicts desperately searching for alternatives when their prescribed or unprescribed drugs ran out. To compensate for opioid withdrawal, users often seek out heroin and fentanyl on the street, and since dealers have started to add carfentanil to heighten the potency of those drugs, overdose rates have climbed to unprecedented numbers.7

“It’s a very different process detecting carfentanil in post-mortem blood, where the concentrations are literally a billion or a trillion times lower.”

-Dr. Graham Jones, Chief Toxicologist, Alberta’s Medical Examiner’s Office.8

What’s being done about it?

Experts are urging the federal government to combat the influx of opioids, and especially carfentanil, by providing safe consumption sites that are supervised and which offer counselling and anti-withdrawal drugs like methadone and Suboxone. They are also suggesting that naloxone, which reverses the effects of carfentanil and fentanyl and is so far found only in pharmacies and clinics, should be placed in easily-accessed public places such as nightclubs and public bathrooms.9

Labs across the country are developing tests to confirm cases of carfentanil-related overdose, and performing post-mortem tests on past cases to determine whether carfentanil overdoses were misdiagnosed as fentanyl-related. It’s a difficult process, though, since carfentanil appears in such small doses, “where the concentrations are literally a billion or a trillion times lower.”10

The federal government is also taking on initiatives to combat the opioid crisis, including allowing the importation of drugs to combat the crisis that have not yet been approved for sale in Canada, enabling access to pharmaceutical grade heroin (diacetylmorphine) through a Special Access Programme, increasing access to naloxone, and creating regulations to control fentanyl precursors.11


  1. National Center for Biotechnology Information. PubChem Compound Database; CID=62156, (accessed Oct. 19, 2017).
  3. “What Is Carfentanil?” Recovery First Treatment Center, (accessed Oct. 19, 2017)
  4. Miller, Adam. “Ontario Street Drugs Test Positive for Carfentanil for 1st Time: Health Canada.”Global News, 7 Dec. 2016,
  5. “Police Seize 42 Kilograms of Deadly Opioid Carfentanil from Pickering Home.”, 16 Oct. 2017,
  6. News, CBC. “At Least 2,458 Canadians Died from Opioid-Related Overdoses in 2016: Report.” CBCnews, CBC/Radio Canada, 6 June 2017,
  7. Ireland, Nicole. “Fentanyl Drug Crisis ‘Spreading like a Cancer’ across Canada, Expert Says.”CBCnews, CBC/Radio Canada, 24 Dec. 2016,
  9. Ireland, Nicole. “Fentanyl Drug Crisis ‘Spreading like a Cancer’ across Canada, Expert Says.”CBCnews, CBC/Radio Canada, 24 Dec. 2016,
  10. Stewart, Briar. “Elephant Tranquilizer Now so Common as Recreational Drug, Alberta Is Testing for It in Autopsy.” CBCnews, CBC/Radio Canada, 14 Dec. 2016,
  11. Canada, Health. “Federal Action on Opioids.”, 23 Aug. 2017,