How hot weather can impact certain patients - and the medications they take

Published on Saturday, August 1, 2020

By: Gary Pettus, gpettus@umc.edu

In the heat of high summer, Mississippians worried about stroke and other health hazards may have an added reason to sweat.

University of Mississippi Medical Center physicians say taking certain drugs can hinder your ability to cope with hot temperatures – disturbing, considering that, among all weather events, heat waves are the No. 1 killer.

“I don’t think people realize how serious it can be if you get overheated and you’re not quickly cooled back down,” said Dr. Sonya Shipley, UMMC associate professor of family medicine (geriatrics). “You can die if you don’t get yourself seen about and allow this to progress.

“Some of the research shows your chance of dying is 50 percent. That’s crazy.”

Still, these medications in question are vital, and normally safe, for treating such conditions as high blood pressure, asthma, allergies, seizures and more. But if the medicated patient becomes too hot, these drugs can be dangerous.

Among them are diuretics, or water pills, commonly prescribed to treat hypertension and heart failure, said Dr. Myrna Alexander Nickens, associate professor of internal medicine (cardiovascular disease).

“Diuretics are very effective in lowering blood pressure,” Nickens said. “But diuretics can dehydrate you.”

They do this by making you urinate more often, which, of course, means you lose more water, Shipley said.

“Diuretics are only one type of blood pressure medicine; other types will not make you lose extra fluid. But diuretics are prescribed so much because they’re affordable and they work.”

Dehydration is also a potential side effect of at least one class of diabetes medicine, Shipley said: the SGLT2 inhibitors, which include empagliflozin, or Jardiance.

Whatever dehydrating medications you take, if your job, hobby or exercise routine requires you to be outdoors on dog day afternoons or mornings, your vulnerability is multiplied.

“If you exercise outdoors, I recommend doing it around 5 or 6 a.m. on really hot days, or after 6 p.m.,” Nickens said. “Doctors do not recommend midday exercise outside.”

Going off medication is usually no option: For instance, people with high blood pressure – that is, above 130/80 mm Hg – are already at an increased risk for heat-induced stroke, said Nickens, who suggests to her patients the purchase of a home blood pressure monitor.

“If your blood pressure is controlled, check it once a week,” she said. Otherwise, check it every day and stay in touch with a health care provider.

During sweltering weather, people who take several medications may be further imperiled, Nickens said.

“Polypharmacy is a big deal. Many elderly patients not only take more than one drug, they may also go to a lot of different physicians, who may not know about those other medications.”

The more drugs, the more chances for troublesome interactions, Shipley said. Even without interactions, some common prescriptions for elderly patients include anticholinergics – medicine for urinary incontinence, overactive bladder and other complaints, including symptoms of Parkinson’s disease. They pose an added risk of heat stroke.

Still, there are ways physicians can take some of the heat off their patients.

“I can either lower the dose or stop it altogether,” Shipley said, “and substitute something else whenever possible.”

Even when it is possible, patients have to do their part, the physicians said.

“Stay cool, stay hydrated and stay out of trouble,” Shipley said.

You can do that, of course, by drinking plenty of water; if you don’t drink enough, your body will tell you, at least eventually.

“This is not a perfect rule of thumb,” Shipley said, “but one easy thing to do is monitor how often you have to use the restroom. You should have to void every two to three hours or so. If you find that you don’t need to after four or six hours, that lets you know you are walking around dehydrated.

“So, lots of people are walking around dehydrated.”

The problem with warning signs is they may arrive too late. Typically, they include nausea, dizziness, rapid heartbeat, weakness and feeling overheated, Shipley said.

A headache may strike, or dimmed vision – “it’s like a shade is falling over you,” Nickens said. And you may fall yourself – faint, that is, if your blood pressure drops too far.

These are symptoms of a medical emergency, Shipley said.

“You want to stop what you’re doing before it gets to that point. When you feel bad, get into a cooler environment and make sure you’re getting enough fluids.”

Heat is not only a threat to patients, it’s also a menace to the health of their medications.

“Heat can change the way they work,” Nickens said. “This is true for the diuretics and the vasodilators (treatments for hypertension, heart failure and more). And it’s certainly true for insulin.”                                     

Insulin storage has been a problem for some of Shipley’s patients.

“When my diabetics tell me their medicine isn’t working, the first thing I do is find out what they’re doing with it,” Shipley said. “Some have told me they’re taking it with them to work and leaving it in the car. Do not leave your medicine in the car.

“When you first get your medicine, I recommend that you read the insert that often gets thrown into the garbage. It will tell you the proper way to store your medications.

“If you don’t store them properly, they won’t work. Storage matters. Think about it: If you have a pack of chicken and don’t store it properly, that can be bad.”

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