Recent headlines have warned about dangerous record-breaking heat waves in the United States and around the world. Many people may not realize that they are at far greater risk for heat-related illness than others. If you are taking medicines, this kind of heat could increase your risk for heat stroke!
Heat Wave Problems:
That’s especially true if you received a prescription in the fall, winter or spring. Healthcare providers may not be thinking about hot weather in November or March. But some of the medicines they prescribe or dispense can make hot weather especially hazardous.
Not surprisingly, researchers have found that more patients are hospitalized with heat-related problems during heat waves (PLOS One, Dec. 10, 2020). Older people with chronic conditions such as diabetes, hypertension, dementia, lung or kidney disease are most vulnerable. The medications that such individuals must take can put a strain on the body’s ability to dissipate heat or restore its fluid and electrolyte balance.
You Do Not Have an Idiot Light on Your Forehead!
If your body were an automobile, you wouldn’t get far when the water in your radiator boiled away. Ignore the warning light, and you could easily blow the engine.
We were recently on a boat that started to overheat. The impeller that brings in cool water had started to fail, and the alarm sounded as the engine got into the danger zone. It could not be ignored. The captain shut down the motor and called the tow service to get back to the boat landing.
Unlike most boats and cars, humans do not come with alarms that sound off or light up when they overheat. People may not recognize the symptoms of heat exhaustion or heat stroke.
Symptoms of Heat Exhaustion:
First, let’s clear up the differences between heat exhaustion and heat stroke. Heat exhaustion occurs as a result of a loss of fluid. This may occur as a result of not drinking enough to replace sweating losses. The person becomes weak and may feel nauseated, anxious and lightheaded.
When a crowd gathers and stands around for some event in hot weather–a military parade, a baseball game–a concert or a political speed–some folks are overcome by heat exhaustion and they faint. Typically, people with heat exhaustion experience heavy sweating and cool, clammy skin. They often feel dizzy with a rapid heart rate.
Others may have a slow pulse and their skin gets pale and their blood pressure is low. Some individuals report fatigue, nausea, headache and muscle cramps. Rehydrating with electrolyte solutions or sports drinks is crucial along with rest. A victim of heat exhaustion should get to a cool location where they can rest and drink an electrolyte-rich solution such as a sports drink.
Overlooking the warning signs of heat exhaustion could lead to a complications. Don’t ignore the signs of trouble!
Symptoms of Heat Stroke:
Heat stroke, on the other hand, happens when the body’s normal means of losing heat shut down or can’t cope with extreme temperature. Heat stroke is an emergency and requires immediate medical attention. It is characterized by high body temperature, hot skin, fast pulse, headache, dizziness, disorientation, nausea and confusion. The person may pass out. Drinking fluids is potentially dangerous for someone with heat stroke.
The onset of symptoms may be sudden. Heat stroke can result in brain damage or even death. Children and pets have died from heat stroke when they were left in a closed car. We just said it, but we cannot emphasize this enough:
HEAT STROKE REQUIRES IMMEDIATE EMERGENCY MEDICAL ATTENTION!
OTHER SYMPTOMS OF HEAT STROKE:
- Odd behavior, agitation, confusion, hallucinations
- Skin that is red or dry, elevated temperature
- Breathing problems
- Seizures
- Loss of consciousness
Medications That Make You Susceptible to Heat Stroke:
Some medications can make you more susceptible to heat-related illnesses. Like the boat with the broken impeller, a car without a functioning radiator will overheat quickly in hot weather. Humans control heat build-up through sweat evaporating from the skin. As a consequence, medicines that interfere with sweating raise the risk for overheating.
Drugs that slow sweating are especially dangerous. They disable the body’s “radiator” and make cooling more difficult. You would be amazed at how many medications have this effect, though it is not something that is commonly mentioned by prescribers or dispensers. Anticholinergic agents such as those used for overactive bladder or Parkinson disease reduce sweating. Another anticholinergic medication is the antihistamine diphenhydramine. It is found in the brand name drug Benadryl and in PM pain relievers. Anticholinergic drugs may put people at risk for heat exhaustion or heat stroke.
Antidepressants and Heat Stroke:
Antidepressants such as amitriptyline (Elavil), desipramine (Pertofrane and Norpramin), doxepin (Sinequan), imipramine (Tofranil) and nortriptyline (Pamelor) are especially dangerous in this regard. Such drugs have anticholinergic activity. That means they interfere with sweating.
A lot of people are prescribed amitriptyline for nerve pain (peripheral neuropathy). The likelihood that someone would be warned NOT to cut the grass or engage in vigorous athletic activities in the heat of the summer is low.
Antipsychotics and Heat Stroke:
Antipsychotic medicines prescribed to treat psychiatric conditions such as schizophrenia, bipolar disorder or major depression can also interfere with the body’s ability to regulate core temperature. Such drugs can also make people vulnerable to overheating. Examples include aripiprazole (Abilify), ziprasidone (Geodon) and quetiapine (Seroquel). Many also have anticholinergic activity. An analysis of heat stroke or heat exhaustion over two decades found that the antiepileptic medicine topiramate was strongly associated with such hospitalizations (European Journal of Clinical Pharmacology, April 3, 2023).
Antihistamines and Heat Stroke:
Over-the-counter antihistamines and motion sickness medicine can also make people more vulnerable to the heat. An athlete taking diphenhydramine (Benadryl ) or clemastine (Tavist) to relieve congestion or sinusitis might end up in the hospital because the body can’t get rid of the excess heat generated by exercise.
Antipsychotic medications are especially problematic. Such drugs are now being added to antidepressant regimens, but adequate warnings about heat stroke may be missing from the discussion about complications.
Bladder Drugs and Heat Stroke:
Many medications that are prescribed for “overactive bladder” also have anticholinergic activity. Drugs such as tolterodine (Detrol), oxybutynin (Ditropan), darifenacin (Enablex) or solifenacin (VESIcare) could pose risks for people without air conditioning or for those who overdo it outside.
One reader commented on this class of medications:
“I am so thankful you have told us about the dangerous connection of anticholinergics to heat stroke symptoms. In the coastal Northwest we are not used to 100-degree heat that goes on for days. At night, when the outside air cools, that heat is released and temperatures inside the house rise instead of cooling off. Our body temperatures can rise just when we expect relief. Avoiding anticholinergics is very important.”
Anticholinergic Drugs:
Anticholinergic drugs in general may pose a problem when it gets warm. There are scores of such medications and prescribers may not even realize that the medicine they have prescribed for an overactive bladder problem can have strong anticholinergic activity and thereby make a patient more susceptible to heat stroke.
You can find an extensive list of such drugs at this link and in our Guide to Drugs & Older People or in Top Screwups Doctors Make and How to Avoid them. When you get done reviewing the list you will likely know more about anticholinergic drugs that your health professional. By the way, such medications can also give you fuzzy brain. That is to say, the very same drying effect that makes people more susceptible to the heat can also scramble the synapses and cause confusion or memory problems.
Cardiovascular Drugs and Heat Stroke:
Losing fluids and electrolytes can also complicate the body’s efforts to stay cool. That is why certain high blood pressure pills such as diuretics can lead to trouble. When that happens, the body may become more susceptible to high temperatures.
In addition to sweating, the body also deals with heat by dilating blood vessels to help heat escape. Medications that block this ability may also increase the chance of heat-related harm. That might include beta blockers such as atenolol, metoprolol, nadolol or propranolol, because they lower heart rate and decrease blood flow to the skin, where it can be dissipated. This involvement of cardiovascular drugs might explain why heart attacks are also more likely during hot weather.
Please don’t forget that alcohol is also a diuretic and makes heat exposure more dangerous.
What Should You Do?
Needless to say, no one should stop taking their medications just because the thermometer is rising. However, if you are taking prescription medications, we urge you to discuss the potential risks with your pharmacist or prescriber. They should be able to advise you how to stay adequately hydrated and cool enough, even if it means you need to visit a place with air conditioning.
You may want to learn more about the problems of medication contributing to heat stroke during hot weather. Our Show 1348: How Heat Challenges Human Health offers a great deal of information.
The next time someone asks the stupid question, “hot enough for you?” that’s your cue to find out if your pills are making you more sensitive to heat damage. If you know someone who might be susceptible to higher temperatures because of medications, please share this article with them. It just might save their life.
