Wastewater monitoring shows first detection of two new substances of concern in the NWT
Press Release
NORTHWEST TERRITORIES (July 21, 2025) –The Chief Public Health Officer advises the public that two new substances of concern have been detected in in Yellowknife’s wastewater (See Wastewater Monitoring in Yellowknife, below) – isotonitazene and xylazine. The substances were identified in the most recent National Wastewater Drug Surveillance (NWDS) report for the Yellowknife site, which used data from May 2025.
This is the first time these substances have been detected anywhere in the NWT. Both substances can cause harmful effects in humans based on potency. Neither can be detected with a fentanyl test strip. The report also showed that fentanyl analogue – synthetic opioids structurally related to fentanyl that have similar effects was also present at detectable levels for only the second time since wastewater monitoring began in July 2024.
About Isotonitazene
Isotonitazene is a synthetic opioid of the benzimidazole class (also called nitazenes), and acts similarly to fentanyl. Isotonitazene is estimated to be more potent than fentanyl, but data is limited. Overdose can be reversed with Naloxone. Nitazenes are chemically distinct from fentanyl and cannot be detected with a fentanyl test strip.
Nitazenes were first synthesized in the 1950s as research chemicals, but have never been adopted for clinical use due to unpredictable pharmacokinetics and the availability of safer alternatives. They have been increasingly detected in Canada since 2024. In April 2025, RCMP in Fort Saint John, BC, reported three deaths attributed to counterfeit “Oxycet” tablets laced with isotonitazene.
About Xylazine
Xylazine is a potent sedative often used to alter illegal opioids, including fentanyl. It is an α2-adrenergic agonist, not an opioid, which means that naloxone cannot directly reverse its effects. It also cannot be detected by a fentanyl test strip.
Xylazine is used as a tranquilizer in veterinary medicine and is sometimes diverted from stocks into the illegal drug supply. Clusters of overdoses in jurisdictions across Canada since early 2024 have been attributed to xylazine mixed with fentanyl.
Health risks
There are no visible warning signs that street drugs contain nitazenes or xylazine. You cannot detect them by sight, smell, or taste. Importantly, these drugs cannot be detected by fentanyl test strips – a negative test does not mean your drugs are safe!
Isotonitazene is an opioid: an overdose will look the same as one caused by fentanyl or other opioids. There is no way to differentiate nitazene poisoning from any other opioid without advanced testing.
Xylazine typically worsens opioid overdose and will also present similarly to a normal overdose. Some unique features of overdoses involving xylazine include:
- Naloxone may be less effective, and sedation may persist even if breathing is restored
- Possibility of severe skin ulcers at the site of injection
What to do if you suspect an overdose
If you suspect an overdose, call 911 or your local health centre. Signs and symptoms of opioid overdose can include the following:
- difficulty walking, talking or staying awake
- dizziness and confusion
- very small pupils
- unresponsiveness (unable to wake up, even when shaken or shouted at)
- signs of hypoxia
- slow, weak or no breathing
- blue, purple or grey lips or nails
- cold and clammy skin
- choking, gurgling or snoring sounds
Click here for more information about Opioid Overdose Prevention.
NOTE: While Naloxone, an opioid reversing agent, will not stop effects of xylazine, it should still be used as it will reverse the effects when opioids are also consumed. It is important to know that xylazine may cause sedation that will last even after naloxone has restored normal breathing. Additional doses may not be required but emergency responders (9-1-1) should still be called to help.
What this means for NWT residents
We cannot tell how these drugs are appearing on the street just from information gathered from wastewater. They are most commonly used as additives to alter illegal opioids, but users of all drugs are urged to take extra precaution.
Wastewater monitoring in Yellowknife
In July 2024 the CPHO entered a Memorandum of Understanding with the City of Yellowknife to pilot monthly testing of Yellowknife’s wastewater for controlled substances. Results are released to the public every 6 months via the Canadian Drug and Substance Watch (CDSW) website(link is external). The CPHO continues to work with healthcare providers, first responders, coroners, RCMP and other frontline workers to achieve better information in the NWT.
- The processing time between sampling and reporting is at least 6 weeks, meaning that we have just received and are referring to the May 2025 data.
- Wastewater is complicated to measure – samples will not reflect all drugs in Yellowknife or the NWT.
- The data provided by the National Wastewater Drug Surveillance is qualitative, not quantitative, so we can only determine the presence of a substance, not the amount.
- A substance is identified when its concentration is above the limit of detection of the measurement instrument (in this case, a mass spectrometer). A substance may be present but at levels too low to detect.
- Detecting a substance for the first time does not guarantee it was not here before – only that it is here now.
Legal Protection
The Good Samaritan Drug Overdose Act (link is external)protects people involved in an overdose from being charged for possession of a controlled substance. This law encourages anyone to call for help if they witness or experience an overdose.
People who use drugs should use them with others present, start with small amounts, and should have naloxone nearby and know how to use it. Don’t mix drugs with other drugs, or with alcohol. Mixing substances increases the risk of overdose.
More Information:
- Drugs in the NWT
- Opioid Overdose Signs and Symptoms
- Where to get Naloxone in the NWT
- CCENDU xylazine fact sheet(link is external)
- CCENDU nitazene fact sheet(link is external)
For media requests, please contact:
Andrew Wind
Manager, Communications
Health and Social Services
HSSMedia@gov.nt.ca(link sends e-mail)
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