How Common Medications Affect Heat Tolerance

Millions of Americans may miss heat-related illness warning signs unless they know how their medications could interact with the weather.

Illustration by The Epoch Times, Shutterstock

Extreme heat is risky on its own—but the risk is compounded for millions of Americans taking commonly prescribed and over-the-counter medications.

Many people don’t connect the dots when an adverse reaction is taking place; instead, they assume hot weather simply feels harder to tolerate. “I’m not sure that awareness is high enough yet—that some of the medications people may be taking might make them more susceptible to heat-related illness,” Dr. Jan Carney, professor, public health researcher, and president of the American College of Physicians, told The Epoch Times.

Knowing how medication can alter physiology—by causing dehydration, disrupting body temperature, or triggering too much or too little sweating—can go a long way toward preventing heat-related medical emergencies. The end goal isn’t to avoid going outdoors but to be prepared on days of high heat and humidity.

How Common Medications Up Heat Stroke Risk

The highest risk of heat stroke comes from drug combinations, particularly heart failure or blood pressure medications such as angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blocker (ARB), or angiotensin receptor-neprilysin inhibitors taken alongside diuretics, which increase urine output. In hot weather, the combination can increase the risk of dehydration, dizziness, kidney injury, and heat-related illness.

The Centers for Disease Control and Prevention has identified several ways medications increase heat sensitivity:

• Reduced Thirst: Diuretics, ACE inhibitors, ARBs, opiates, benzodiazepines, antipsychotics, antidepressants, anticonvulsants can reduce thirst. The mechanism varies by drug but often involves hormonal, brain, or binding changes that blunt our ability to perceive thirst.
• Disrupted Temperature Control (via the Hypothalamus): Antipsychotics, stimulants, and anticholinergics can disrupt the body’s temperature control. Stimulants rev up metabolism and respiration, which increase internal body temperature; antipsychotics dilate blood vessels and trick the body into thinking it’s warmer than it is; and anticholinergics use neurotransmitters to block receptors that tell the body to sweat.
• Impaired sweating: Temperature control disruption makes it hard for the body to cool itself from the effects of SSRIs, other antidepressant medications, certain antipsychotics, and anticholinergics.
• Electrolyte Imbalances: Imbalances may occur from diuretics, beta blockers, and calcium channel blockers due to changes in kidney function and from antacids and laxatives that alter the gut’s ability to absorb minerals.
• Changes in Circulation and Oxygen Delivery: Heat-related dizziness and fainting from non-steroidal anti-inflammatory drugs affect kidney function and fluid retention; diuretics cause fluid and blood loss; beta blockers overtax the heart, leaving little capacity for pumping blood that cools the skin; and laxatives alter blood volume and deplete electrolytes.

“There are a lot of medications that contribute to this. Many, many people take these types of medications, but I definitely don’t think everyone knows that they’re at increased risk,” Stacey D’Angelo, a Toronto pharmacist and founder of Your Simple Health, told The Epoch Times.

The risk isn’t limited to older adults. Children and teens commonly take medications that raise heat sensitivity, including antihistamines, which cause drowsiness; stimulants such as methylphenidate for attention-deficit/hyperactivity disorder; tricyclic antidepressants; selective serotonin reuptake inhibitors; and diuretics—yet this risk is often overlooked by parents and caregivers.

Other Contributing Factors

Medication isn’t the only variable. Young children, pregnant women, anyone with heart disease or asthma, and older adults all face exacerbated risks, Carney said.

“We also have to think about your occupation, how much time you are spending outside, and your zip code,” she added. “Where you live becomes really, really important in terms of the heat.”

Heat waves are increasingly more frequent, longer, and more intense than they were in the 1960s—rising from averages of two to six events per year, lasting four days instead of three, and running half a degree hotter than the local threshold. Heat-related deaths are also up, rising from 824 in 2016 to 2,325 in 2023, according to research published in JAMA.

“We have had in recent years prolonged heat waves that have had very severe health effects in terms of ER visits and also deaths in the Pacific Northwest, for example, in 2021,” Carney said. “We know these phenomena are happening.”

The intersection of climate, an aging population, rising medication use, and heat-related illness warrants critical attention, according to a review published in Pharmacy.

The problem is that CDC guidance is based on drug mechanisms, not solid research about how each medication—or the interaction of multiple medications—might be driving up heat-related illness.

Compounding the problem, people at the highest risk of heat-related illness tend to underestimate their own risk, according to a study in Nature Communications—a mismatch Carney says “can be sort of a false sense of security.”

The CDC has created an online heat and air quality tracker with color-coded heat risks. This tool can be especially beneficial for traveling, which can increase your risk if you are unfamiliar with the climate or haven’t checked the forecast, and for those who enjoy outdoor exercise. Strenuous exercise can raise the body temperature a few degrees. Add heat, humidity, dehydration, or too much clothing to outdoor exercise, and you have a perfect storm for high heat illness risk.

Additional risk factors include drinking alcohol and obesity.

Recognizing the Warning Signs

Heat-related illness often has subtle warnings—a pesky muscle cramp, a stomach that feels a bit off, fatigue, or excessive sweating that might at first seem normal for a hot day.

“Those are kind of early signs to stop, go into a cool place, make sure you are well hydrated, and take it from there,” Carney said.

Sometimes those signs come only minutes before a heat stroke—or not at all. Acting fast is essential. When the body’s temperature rises to 106 degrees Fahrenheit within minutes and cannot cool down, it can cause heat stroke. The most serious heat-related illness, heat stroke can cause permanent disability or death.

“It can happen to anyone when we can’t cool down our bodies through the natural mechanisms,” D’Angelo said.

Other warning signs of heat stroke include hot and dry skin, confusion, slurred speech, profuse sweating, loss of consciousness, and seizures. Delayed treatment—which should include getting in the shade and getting the skin wet, in an ice bath or cool tub of water if available—can cause brain and organ damage and death.

How to Stay Safe Without Giving Up Summer

Medications can make heat-related illnesses harder to avoid, but they remain highly preventable.

Those at high risk who want to enjoy the benefits of being outside can go outdoors on most days in the early morning or after dusk. “Notice how you’re feeling, and if you’re not feeling well, get into the shade or air conditioning, drink, and get medical attention if you’re not feeling right, before it gets too severe,” D’Angelo said.

Outdoor workers should inform employers of their increased risk of heat-related illness due to medication and seek accommodations if necessary, such as asking for access to a shady place to take breaks.

Don’t quit your medication without consulting a physician, as many require a deprescribing plan, D’Angelo said.

“We should not stop what we’re doing but just be prepared,” Carney added. “Knowledge is power here.”