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staying cool: managing heat sensitivity while living with chronic disease and medication

with the dog days of summer here, it's more important than ever to understand your health as it relates to the heat and what you can do to avoid heat-related illness.

certain chronic diseases and medications increase heat intolerance, putting some people at a higher risk for heat-related events. getty images
summer has officially begun, and with it comes the promise of heat waves nationwide. according to environmental and climate change canada (eccc), the entire country is expected to experience hotter-than-seasonal temperatures this summer season.
with that, many people with chronic disorders and those who require specific medications are subjected to feel as though the ac can’t be cranked high enough.
as it turns out, various diseases and medications can affect thermoregulation in the body, making the heat feel a little less comfortable than you’re used to. for those affected by this, the risk of heat-related illness, such as heat exhaustion and heat stroke, is much higher, making it crucial to put a special emphasis on staying cool in the dog days of summer.

thermoregulation and extreme heat

the human body maintains a set temperature between 36 and 37 degrees celsius to function at its best. at these temperatures, no extra energy is needed to maintain core temperature. however, when the weather becomes hotter, the body has to pull out all the stops to cool itself down.

if the weather hits temperatures between 40 and 50 degrees celsius, the body’s ability to get rid of excessive heat , a process known as thermoregulation, becomes compromised, as does the optimal function of bodily processes.

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thermoregulation is the term used to describe how body temperature is regulated. the area of the brain tasked with keeping thermoregulation working as it should is the hypothalamus.
when exposed to extreme heat, the hypothalamus does this in three ways: by driving the body to sweat when it begins overheating, dilating blood vessels in the skin, arms, face, and feet to help move heat out of the body, and causing discomfort in high heat that drives a person to seek out shade or a cold beverage.
unfortunately, the process of thermoregulation is often impaired in people living with certain chronic diseases, as well as those who take specific medications.

heat tolerance with chronic disease and medication use

people living with chronic diseases can be especially intolerant to extreme heat. conditions that affect how a person experiences heat and drive poor thermoregulation include:
  • neurological diseases, including parkinson’s and multiple sclerosis
  • brain or spinal cord injuries
  • tumours
  • endocrine disorders, such as hyperthyroidism
  • diabetes
  • obesity
  • cardiovascular disease
these conditions can lead to a higher risk of developing adverse reactions to extreme temperatures, including excessive sweating or being unable to sweat enough in the heat, exhaustion and fatigue in warm weather, changes in mood, and nausea, vomiting, or dizziness.

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people who take certain medications are also at risk of developing the symptoms of heat exhaustion or heatstroke when exposed to extreme heat. in some cases, the medication itself causes an issue with thermoregulation in the brain because of its effect on the hypothalamus, as is the case with antidepressants and antipsychotics.
in others, medications can change how the body perceives heat, making it less able to respond to overheating adequately.
the drugs most likely to cause an issue with extreme heat include:
  • diuretics: these drugs increase urine production, which causes excessive fluid loss. that can lead to a decrease in sweat production and dehydration.
  • beta-blockers: these drugs slow down heart rate, hindering blood circulation that cools down the body.
  • stimulants: by increasing the metabolic rate, stimulants impair cooling mechanisms in the body.
  • antihypertensives: by causing a decrease in blood pressure and reduced feelings of thirst, antihypertensives can lead to increased heat intolerance.
  • anticholinergic medications: these drugs block signalling in the brain that drives sweat production, resulting in less sweating and more overheating.
  • angiotensin-converting enzyme (ace) inhibitors: these drugs reduce a person’s ability to feel thirst, even while dehydrated, leading to potential overheating.
  • antiseizure medications: certain antiseizure drugs can cause increased sweating and urination, leading to dehydration and overheating.

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it’s also possible that people who need more than one medication may reduce their heat tolerance even further, depending on how many drugs they take. for example, if someone takes antidepressants and beta-blockers, it can double their heat sensitivity, increasing the risk for severe heat-related illness.

heat-related illnesses

there are several heat-related illnesses to be aware of. the most worrisome three are heat syncope, heat exhaustion, and heat stroke.
heat syncope is a type of fainting driven by exposure to extreme temperatures. people who experience heat syncope will likely develop sudden dizziness and light-headedness before losing consciousness. this type of heat-related illness is especially harmful because it can lead to falls, injuries, and accidents while driving.
heat exhaustion occurs when a person becomes so overheated they lose excessive water and electrolytes in sweat. the general symptoms of heat exhaustion include:
  • heavy sweating
  • muscle cramps
  • extreme fatigue or weakness
  • nausea
  • vomiting
  • headaches
  • dizziness
  • a standard or slightly high body temperature
  • fast and weak pulse
  • shallow and fast breathing
  • clammy, pale, cool, or moist skin
  • fainting

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heatstroke is the worst type of heat-related illness and is often fatal if a person does not seek out emergency medical treatment. people who develop heatstroke will notice symptoms, such as a lack of sweating, mental confusion and delirium, twitching muscles, and seizures. other symptoms of heatstroke include:
  • dizziness
  • convulsions
  • rapid and weak pulse
  • throbbing headache
  • shallow breathing
  • hot and dry skin that could be red, bluish, or mottled
it’s essential to pay attention to these signs of heat-related illness, especially if you fall into the category of high risk based on a chronic disease or medication. unfortunately, not taking these medications isn’t an option for those with chronic diseases, so other measures must be taken to keep cool and avoid heat-related health events.

how to keep cool with chronic disease and medication use

to ensure you aren’t putting yourself at risk this summer, it’s best to practice cooling techniques whenever necessary. the first and most effective is to avoid the heat altogether by staying inside an air-conditioned place until the heat subsides.
however, since that may not always be possible, other options to cool yourself down are available. they can lower your risk of developing heat-related illnesses while increasing your ability to feel comfortable in hotter temperatures. they include:
  • drinking cool liquids such as water to cool off internally.
  • immerse yourself in cold water by having a cold bath or shower or going for a swim if outdoors.
  • place an ice or cold pack on areas close to surface-level veins, such as the wrists, neck, chest, and temples, to cool down the blood circulating in your body.
  • avoid movement as much as possible.
  • wear light and breathable clothing to avoid sun exposure as much as possible. you can also walk with an umbrella or take breaks in the shade as often as you need them.
  • speak to your doctor about heat-regulating supplements that can be taken alongside your current medications, such as primrose oil or black cohosh.

while staying cool in the summer isn’t always easy, especially in canada, where record-breaking temperatures seem to occur regularly, it’s vital for many people who are sensitive to heat.

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angelica bottaro
angelica bottaro

angelica bottaro is the lead editor at healthing.ca, and has been content writing for over a decade, specializing in all things health. her goal as a health journalist is to bring awareness and information to people that they can use as an additional tool toward their own optimal health.

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