As temperatures soar again this week, health experts are warning that the heat can have an adverse effect on people taking certain medications or street drugs.
A yellow-level heat warning is in effect, and Tuesday is expected to be the hottest day in southern Ontario, with temperatures reaching the mid-30s C and the humidex making it feel more like the mid-40s.
Dr. Samir Gupta, a respirologist at the University of Toronto, says some common prescription medications — such as for high blood pressure, heart disease and mental health disorders — can increase a person’s vulnerability to heat and impact how the body cools itself.
“People are living longer, and that means they’re living with more and more chronic conditions, and that means they’re on more and more medications to manage those conditions, and unfortunately, some of the most common chronic diseases require medications that have an impact on the body’s ability to tolerate heat,” Gupta told CBC Saskatchewan’s The Morning Edition.
“Don’t forget that sweating is our most effective way of getting rid of heat. The problem is that many of these different medications have what’s called an anticholinergic effect, which is when they inhibit the signals used by our nervous system to tell our sweat glands to produce sweat.”
Gupta said anti-depressants can interfere with the brain’s ability to regulate heat, and some anti-depressants increase sweating, raising the risk of dehydration.
Anthistamines, commonly used at this time of year for allergies, can inhibit sweating, while beta blockers and Aspirin can impair the ability of blood vessels to dilate — to radiate heat outward and cool down the body.
Diuretics help keep body fluids at a lower level, so if you’re on them, “when it’s hot and you start sweating on top of that, you become very susceptible to dehydration.”
“Other blood pressure pills can actually reduce your thirst sensations.”
Any blood pressure medication can pose a risk when it’s hot out because becoming dehydrated from sweating will cause blood pressure to drop.
Gupta also recommends keeping medications stored in a cool and dry place.
“Most medications are not designed to be kept in a hot environment,” he said.
If the temperature inside a living space begins to rise, or if medications get left in a hot vehicle, “they can be degraded by that heat and stop working properly,” Gupta said.
He noted insulin should be kept at temperatures below 30 C, and Epipens can deliver less epinephrine when they become too warm, so should be stored at temperatures below 25 C.
“One thing to keep in mind as well is that heat waves can trigger power outages because of the strain on the grid, and some of my patients are on, for example, nebulizers that require power for their inhaled medications — some have an oxygen concentrator,” he said.
“These are life-sustaining treatments, so these patients absolutely need a backup plan in case of a power outage.”
At the start of July, Waterloo region’s overdose monitoring system issued a community drug alert after 44 suspected overdoses and one death between June 28 and July 2.
Part of that alert warned, “People who use drugs have an increased risk of death and overdose/ drug poisoning during very hot weather.”
Windsor-Essex County Health Unit’s opioid and substance use notification system also reported an elevated number of overdoses between June 28 and July 4: 29 opioid overdoses were reported, 19 of which involved fentanyl.
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Julie Kalbfleisch is a spokesperson for Sanguen Health Centre, which helps people experiencing homelessness across Waterloo region with a drug testing program and a community health van.
“We know that heat can actually cause a more adverse reaction with certain drugs, and because people don’t always know exactly what they’re taking, that increases the risk as well,” she told CBC K-W’s The Morning Edition.
Through the drug-checking program, Sanguen is seeing “some very concerning substances,” including unregulated drugs or medications meant for veterinarian use, including tranquillizers, Kalbfleisch said.
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She said anyone witnessing someone possibly in distress outdoors should ask if they’re OK, and look for signs, including:
It may be someone is just asleep, she said. Or it may be something more serious.
“Shout to them to see if you can get them to wake up. Raise your voice gradually,” she said.
“You may want to gently shake their shoulders. You can do stuff like a trapezius squeeze or a fingernail pinch, even a collarbone rub. And then say verbally that you’re going to administer naloxone and call 911.”
Both street drugs and prescribed medications can pose a risk when in the sun. Gupta said they can cause photosensitivity — making someone more sensitive to the sun and at risk of sunburn.
Prescribed medications including for cholesterol, some antibiotics, diuretics, or over-the counter anti-inflammatory medications like ibuprofen could also pose an issue.
He said people should avoid the sun or use as much protection as possible.
“We do not want you to stop your medications,” he said about dealing with the possible side-effects of medication and heat.
“In some cases, your doctor might tell you to decrease the dose or maybe even the frequency during a heat wave, but the most important thing is to be able to recognize the signs and symptoms that heat might be interacting with your meds … so that you are aware when this is happening and can take those extra precautions to protect from heat exhaustion and heat stroke.”
