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Horse tranquilizer Xylazine found in Sudbury opioid supply

New toxic ingredient leaving users in severe cognitive distress and causing wounds and necrotic skin lesions

A new and toxic ingredient in unregulated opioids in Sudbury is wreaking havoc within the vulnerable population, causing wounds and leaving users in an almost catatonic state. 

Xylazine (pronounced zy-la-zine) is a tranquilizer for large animals, like horses and cows, not for use in humans. It was recently the subject of a series of drug warnings from the Public Health Sudbury and Districts (PHSD).

“As you are aware, the Community Drug Strategy released a Drug Alert on Feb. 15, a Practice Advisory Alert on Feb. 21 and a Drug Warning on March 29 related to the toxic substances circulating in Sudbury and districts,” reads the warning. “We continue to receive ongoing reports from frontline workers regarding unexpected reactions from the use of toxic substances such as increased and prolonged sedation, as well as the development of abscesses or wounds in areas other than injection sites.”

Scarlett Ward is a registered social services worker and harm reduction case manager at the supervised consumption site. She said she had suspicions about the presence of xylazine in the local drug supply after witnessing changes in client behavior after they have injected at the consumption site.

Her suspicions are based on how people in recent months physically react to the drugs they are injecting, reactions she has never seen before in drug-users that have her concerned, said Ward.

“The supply has become very toxic; it's become really scary for folks,” Ward said, noting that while clients' vital signs are good — their oxygen levels and heart rate — the cognitive impairment caused by Xylazine is putting them at high risk. They are unable to make decisions, are subject to violence or harm, and in some cases, unable to move or be cognizant of their surroundings.

“Sometimes they're in a sort of blackout state, where they're truly not aware of what they're doing,” she said. 

They have had to offer extra time and space to some clients who are unable to leave the site safely due to the effect of the drug. Ward said these effects are present even in people who have been using long term. 

“We've seen community members who are seasoned drug users with very high tolerances who become very confused,” Ward said. “They’re not sure where they are, or what they are doing.”

According to the Canadian Centre on Substance Use and Addiction, Xylazine was first reported in unregulated drug supply in 2012. Occasionally used intentionally, it increases the longevity of synthetic opioids, like fentanyl, which are not known for long lasting effects. Xylazine is often known as ‘tranq’ and is used with opioids to enhance and lengthen the high, making it feel more like pure heroin. 

But in the wake of border closings at the height of the pandemic, the import of substances ground to a halt. More diluents, also known as cutting agents (ingredients added as filler material) showed up in testing, including caffeine. Then, an increase in adulterants. 

Adulterants, like Xylazine, are pharmacologically active ingredients that enhance or mimic the desired substance. The adulterants now common in unregulated substances include benzodiazepines, as well as nitazenes, a synthetic opioid first developed in the 1950s. Nicknamed Frankenstein opioids, nitazenes are up to 40 times stronger than fentanyl. Fentanyl is already 50 times more powerful than heroin.

Like opioids, these adulterants (benzodiazepine, nitazenes and xylazine) will lower blood pressure, heart rate and breathing, and mixing the two drugs can put additional strain on the central nervous system, further suppressing breathing and heart function. Unlike opioids, however, xylazine and similar medications are unresponsive to Naloxone, an overdose-response medication used for opioids. 

“Narcan or Naloxone only works with opiate receptors in the brain, so it's not addressing xylazine or benzodiazepines,” said Ward.

Marie Pollock, co-founder of STOPS (Sudbury Temporary Overdose Prevention Society) and harm reduction advocate, tests the substances in Sudbury on behalf of the vulnerable population. She takes samples from people who use substances and sends it to testing facilities in British Columbia or Toronto. 

She has seen many adulterants in the supply lately. Her testing in March revealed that of 123 substance samples checked, 69 per cent of fentanyl samples (purchased under the assumption that it was fentanyl) contained a nitazene and 21 per cent contained xylazine. 

Of the fentanyl samples she sent, 13 per cent were associated with an overdose. All of these samples contained fentanyl in combination with benzodiazepine-related drugs or xylazine and over half contained a high-potency nitazene opioid, which do respond to Naloxone and Narcan, but not as well as true opioids. 

Health Canada operates drug-testing labs across the county that analyze unregulated substances seized by law enforcement. In 2020, xylazine was found in nine samples tested. By 2021, a sharp increase with a total of 414 identifications. In 2022, that skyrocketed to 1,011 samples. That means 62.7 per cent of samples in Ontario contained xylazine, the highest in Canada. (British Columbia found Xylazine in 21.2 per cent of samples). 

In addition to causing toxic poisoning deaths in substance users — Sudbury lost 130 people to toxic poisoning in 2022 —  xylazine is causing a worrisome medical issue. It’s causing gaping wounds, necrotic tissue and open sores all over users bodies, not just in areas where the substance is injected. The wounds are also present on people who smoke substances and do not inject at all. 

Ward said because of the time of year, people are wearing layers of clothing when they visit the consumption site, so if anyone is suffering xylazine-related wounds, staff have not noticed them yet. She suspects that as the weather warms and people wear clothing that exposes more skin, the wounds will be visible. 

“Unfortunately, as time passes and the supply likely becomes more saturated with xylazine, I think we'll be seeing more of that for sure.”

Of the wounds, Ward said they are atypical to what they normally see at the consumption site. 

“It's not abscesses at an injection site, which we're usually so familiar with,” said Ward. “It’s at random, typically on the limbs, like on the arms and legs, and the acuity and the intensity of the wounds are quite unique to xylazine.”

Registered members of the consumption site are able to access testing strips for fentanyl and benzodiazepine, but currently there are no Health Canada approved methods for spot testing xylazine. 

Members are also able to access the services of a nurse practitioner who visits the site once a week. To register, clients are asked to provide a ‘code name’ that they will use while in service. They’re asked about health and medication history, substance and use preferences and any other support they need. There is also a ‘member agreement which outlines some basic behaviour expectations for members and staff, and a rights and responsibilities document that is reviewed with members at the time of their initial intake.

The Community Drug strategy advises that each person who uses substances follow advice including:

  • Don’t use alone. There is the safe consumption site located at Energy Court close to downtown Sudbury. At the supervised consumption site, Narcan is used only as a last resort as they are more able to use medical intervention. There is also a toll-free number you can call if you need to use alone: The National Overdose Response Service Line 1-888-688-NORS (6677)
  • Ask around, know your supply
  • Avoid alcohol when using drugs
  • Use caution, start low and go slow
  • Carry a naloxone kit

If you suspect someone is experiencing toxic poisoning, including from adulterants like benzodiazepine and xylazine: 

  • Call 911
  • Give Naloxone according to instructions included
  • If not breathing, give rescue breaths
  • Give chest compressions. Push hard, push fast. 
  • Place the person on their side if breathing on their own
  • Stay until help arrives as the overdose symptoms may come back

Jenny Lamothe covers vulnerable and marginalized communities for .


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Jenny Lamothe

About the Author: Jenny Lamothe

Jenny Lamothe is a reporter with She covers the diverse communities of Sudbury, especially the vulnerable or marginalized.
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