The number of drug overdoses is rising across southern Ontario and some experts say the extreme heat could be partially to blame.
Twenty-nine overdoses, 19 involving fentanyl, were reported in Windsor-Essex during the week of June 28 to July 4, prompting the public health unit to issue a drug alert. Public health officials said there were an “elevated number” of opioid overdoses reported by emergency departments.
On June 24, the Southwestern Public Health Unit (SWPH) issued a drug alert for potential xylazine, fentanyl and benzodiazepine found in the street drug supply. While no data was available, a spokesperson for SWPH told Global News they continue to hear reports from community partners about a rise in overdoses in the community.
On July 3, Waterloo Region Public Health issued multiple drug alerts. One warned about the increasing number of street drugs containing fentanyl, while the other cautioned users about extreme heat.
People at highest risk face a list of aggravating circumstances that leave them more vulnerable. The Welcome Centre Shelter in Windsor, Ont., has noticed this summer that people experiencing homelessness, or others who don’t have access to cooling spaces, are in greater need of care.
Get breaking National news
Get breaking Canada news delivered to your inbox as it happens so you won’t miss a trending story.
“Last week in particular with the high heat advisory, it was indeed a noticeable increase,” Anastasia Adams, a harm reduction co-ordinator at the shelter for women and children, told Global News. “The higher temperatures impact an individual’s thermoregulation, can increase risk of dehydration and without access to a cooler space those in active substance use are at a greater risk of overdose and/or heat-related illnesses.
“Because of this, during heat events, people who use substances should definitely be considered a priority population.”
Following the extreme heat wave last week, the Welcome Centre opened its own cooling space to accommodate people seeking reprieve from the heat. At the cooling centre, Adams said they also offer harm reduction services.
“Access to cooling centres is essential at this time with staff who are trained to respond to drug poisonings or overdoses and are able to offer harm reduction materials and education,” she said. “Those in active substance use are often excluded from some of these services and focusing on a harm reduction, lower barrier approach is paramount.”
Heat is not the only factor driving the rise in overdoses, but it can serve as a compounding factor, Dr. Hawre Jalal, a professor in the School of Epidemiology and Public Health at the University of Ottawa, told Global News.
“People go to a slow state of metabolism and respiration … and they won’t be able to breathe,” he said about the physical consequences of using pure opioids.
“That’s what causes the overdose and leads to mortality.”
While there is no direct interaction between heat and opioids, he said heat adds stress on the body, significantly increasing the load on the cardiovascular system.
“The symptoms of the overdose and the heat might mix together,” he said. “So it becomes harder to diagnose an overdose because of that.”
When other types of drugs are mixed into the supply, the consequences can be even more extreme.
Jalal said first responders also need to evaluate if a patient needs to be treated for heat exposure when treatment for an overdose is given.
If you suspect someone is experiencing an overdose, call 911.
© 2026 Global News, a division of Corus Entertainment Inc.
