What you should know about taking medication during hot weather

Taking certain medications during heat waves can lead to a slightly higher risk of heat-related illness, doctors say, but it can be more dangerous to stop taking medication.

Be aware and take proactive steps, but don't stop taking prescribed medication: doctor

A photo of sun peaking through tree branches.
The sun peeks through the clouds in Calgary in June 2022. (CBC)

Taking certain medications during heat waves can lead to a slightly higher risk of heat-related illness, doctors say — but it can be more dangerous to stop taking medication.

Social media posts, like the one shown below, provide warnings that certain medications can interfere with the body's ability to regulate temperature. These posts are true to an extent, says Mark Yarema, medical director of Alberta Health Services' Poison and Drug Information Service, but the contribution of medication to most heat illnesses is "pretty minimal."

"Withdrawing from medications can also be quite devastating if not done properly," said Yarema, adding that people shouldn't stop taking their regular medication just because it's hot outside.

"It just means that if you have questions to make sure that you ask for help, so ask your physician or ask your pharmacist, and to take the common sense approaches that happen every summer in terms of heat waves."

Yarema said one of the best things people can do is simply be aware if they're taking medication that might affect them during a heat wave. He groups those medications into two categories.

Some have a direct effect on the body. For example, some antidepressants, anti-psychotic medications and allergy medications, like Benadryl, can interfere with the ability to sweat properly, while some blood pressure medications are diuretics, causing fluid loss and leading to a slightly higher risk of dehydration.

Medications in the second category have what Yarema calls an "indirect effect" during hot weather. This includes some antidepressants and anti-psychotics, but it's more likely sedatives like sleeping pills or anxiety medication.

"There's a change in the person's behaviour that affects their ability to normally take those protective actions against heat illness," said Yarema.

Antidepressants including Paxil can affect the body's ability to sweat, slightly increasing the risk of heat-related illness. (Joe Raedle/Getty )

Many of those side effects are more common during the first couple weeks taking a new medication as the body adjusts.

"Most people who take these medications, as long as they're taking them as directed and can also recognize some of the earlier signs of heat illness, such as fatigue and increased thirst and and things like that, and can take steps to get out of the sun, they'll be fine," said Yarema.

Calgary EMS spokesperson Stuart Brideaux says with most heat-related calls EMS receives, there are other factors like alcohol at play.

"Certain medications may or may not really be having the largest effect on someone's ability to to cope with the heat and sun," said Brideaux.

Medications that do affect the ability to sweat or regulate temperature just emphasize the importance of taking normal proactive steps during hot weather, according to Brideaux.

"The top three things of staying really well hydrated with just plain, straight, cold water, using sunscreen and sort of wearing or carrying your own shade [such] as a ball cap or a broad-brimmed hat, those things just go a really long way to your body's tolerance in enjoying the sun."


Sarah Moore

Online journalist/associate producer

Sarah Moore joined CBC Calgary as an online journalist in 2021. If you have a tip or story idea, send her an email at


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