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Data indicating carfentanil increase in Ontario

Posted on Wednesday August 28, 2019

Ministry of Health
Office of Chief Medical Officer of Health,
Public Health
393 University Avenue, 21st Floor
Toronto ON M5G 2M2
Telephone: (416) 212-3831
Facsimile: (416) 325-8412

June 26, 2019

Dear colleagues,

I am writing to share some important information with you regarding carfentanil in Ontario. While carfentanil has been detected in Ontario previously, recent toxicology data suggest an increase in carfentanil presence in Ontario in the past few months.

Data indicating carfentanil increase in Ontario

There has been a sharp increase in the number of urine broad spectrum toxicology screen samples from LifeLabs that have tested positive for carfentanil in Ontario, from a range of 0-100 per month in 2017/2018 to over 700 in each of April and May 2019. This increase in carfentanil-positive samples occurred across many Ontario regions. Of note, there has been no change in testing practice or technology over this period. These data are not comprehensive for Ontario, as other community and hospital labs do similar testing. In addition, these data represent only samples from people accessing testing in these settings, and may not be generalizable to other people who use drugs. We do not know whether people were using carfentanil intentionally or unintentionally.

In addition, the Chief Coroner for Ontario Dr. Dirk Huyer has informed us that preliminary mortality data show an increase in carfentanil-related deaths in Ontario in the first four months of 2019. Specifically, carfentanil directly contributed to 142 deaths between January 1st and April 29th, 2019, which is already 50% more than the total number of deaths in which carfentanil directly contributed in all of 2018, which was 95 deaths. Increases in opioid toxicity deaths in which carfentanil directly contributed occurred in many public health unit (PHU) jurisdictions, although specific numbers for each PHU are not available as many investigations are ongoing. Further, the number of carfentanilrelated deaths will likely increase as further data become available on deaths over this period, since a large proportion of the death investigations for this period are ongoing.

Information on carfentanil

As you may know, carfentanil is a synthetic fentanyl analogue. Data on carfentanil potency are limited, but best evidence suggests that carfentanil is significantly more potent than fentanyl.
Intentional or unintentional carfentanil use could therefore be associated with increased risk of overdose and death compared with use of fentanyl or other opioids.

Prevention and harm reduction opportunities

In this context, I recommend that you share information widely within your jurisdictions to raise awareness of carfentanil in the drug supply, especially with those working on overdose prevention and response and with people who use drugs. Here are some potential key messages:

1. Evidence suggests that there has recently been an increase in carfentanil in Ontario. Carfentanil is a very toxic opioid and people who use carfentanil may be at high risk of overdose.
2. We recommend that people who use drugs take the following measures to reduce their risk of overdose and death:
• Access opioid agonist treatments such as buprenorphine/naloxone (trade name, Suboxone) or methadone.
• Don’t use drugs alone. If this is not possible, ask a friend to check in on you.
• If using drugs with a friend, do not use at the exact same time.
• Carry naloxone and know how to respond to an opioid overdose (
• Use drugs in a supervised setting such as a Consumption and Treatment Service (CTS), where available.
3. Call 911 and administer naloxone to anyone you think is experiencing an opioid overdose. Be prepared to use multiple doses of naloxone, as needed.

If you have questions regarding the data on deaths, you can contact Dr. Huyer at If you have other questions regarding these data or the implications of the data, you can contact Dr. Fiona Kouyoumdjian at


Original signed by

David C. Williams, MD, MHSc, FRCPC
Chief Medical Officer of Health

Cc: Dr. Dirk Huyer, Chief Coroner for Ontario
Dr. Fiona Kouyoumdjian, Associate Chief Medical Officer of Health, Ministry of Health
Dr. Barbara Yaffe, Associate Chief Medical Officer of Health, Ministry of Health
Dr. Peter Donnelly, President and Chief Executive Officer, Public Health Ontario
Dr. Brian Schwartz, Vice President, Public Health Ontario

Helpful resources:
Review of carfentanil pharmacology: