Toronto, ON (May 7, 2026) — After an emergency department visit for an opioid overdose, 9 per cent of individuals died and 21 per cent experienced a repeat opioid overdose in the following year, according to a new study from ICES and the Centre for Addiction and Mental Health (CAMH).
The risks were particularly high within seven and thirty days after being discharged from an emergency department. The mortality estimates were higher than in previous studies, which found non-fatal opioid overdoses to be approximately 6 per cent.
“Most older studies were conducted before the introduction of fentanyl into the unregulated drug supply,” says lead author Dr. Robert Kleinman, a scientist with the Institute for Mental Health Policy Research at CAMH and an assistant professor in the Department of Psychiatry at the University of Toronto. “The current fentanyl supply is highly toxic and associated with a greater risk of overdose or death.”
The researchers evaluated one-year mortality among 28,488 opioid overdose survivors in Ontario, Canada, using linked administrative data held at ICES. Individuals aged 15 to 105 years were included if they visited the emergency department between 2017 and 2023 for a non-fatal opioid overdose.
Within seven days of discharge, 0.6 per cent of individuals died and 2 per cent experienced a repeat opioid overdose. Within 30 days, 2 per cent of individuals died and 6 per cent experienced another overdose. People with additional prior overdose experiences were at an increased risk of death.
“These elevated risks after leaving the hospital highlight the importance of ensuring that interventions such as opioid agonist treatments and take-home naloxone are available and accessible for opioid overdose survivors,” says Dr. Kleinman.
One limitation is that non-fatal opioid overdoses that didn’t result in an emergency department visit were not captured in the study. This means that rates of opioid overdoses during the subsequent year were likely underestimated, and further research is needed to explore overdoses within the community.
“The elevated mortality risk observed in this study is highly concerning. The development of evidence-based care pathways for when individuals with opioid use disorders show up to an Emergency Department with an overdose or in withdrawal may help to both reduce the high mortality rate and help people access treatment,” says Dr. Paul Kurdyak, a senior scientist with ICES and CAMH.
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About ICES
ICES is an independent, not-for-profit health research and data analytics institute that uses population-based health information to produce knowledge on a broad range of healthcare issues. ICES leads cutting-edge studies and analyses evaluating healthcare policy, delivery, and population outcomes. Our knowledge is highly regarded in Canada and abroad and is widely used by government, hospitals, planners, and practitioners to make decisions about healthcare delivery and to develop policy. For the latest ICES news, follow us on Facebook/Instagram or LinkedIn: @ICESOntario
About the Centre for Addiction and Mental Health (CAMH)
The Centre for Addiction and Mental Health (CAMH) is Canada's largest mental health and addiction teaching hospital and a world leading research centre in this field. CAMH combines clinical care, research, education, policy development and health promotion to help transform the lives of people affected by mental illness and addiction. CAMH is fully affiliated with the University of Toronto and is a Pan American Health Organization/World Health Organization Collaborating Centre. For more information, please visit camh.ca or follow @CAMHnews on Bluesky and LinkedIn.
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Misty Pratt
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Media@ices.on.ca
343-961-6982
CAMH Communications
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