Heat Wave Warning: Common Medications That Increase Risk of Heat-Related Illness
Key Insights
Diuretics, beta-blockers, ACE inhibitors, and ARBs can impair thermoregulation, reduce thirst, and contribute to dehydration (search) during extreme heat, raising the risk of dizziness, fainting, and kidney dysfunction.
Antidepressants (SSRIs, TCAs), antipsychotics, and stimulants disrupt sweating patterns and temperature control; lithium poses a specific risk for dehydration (search)-induced drug toxicity.
GLP-1 receptor agonists like Ozempic suppress thirst cues and delay stomach emptying, while SGLT2 inhibitors such as Jardiance may worsen dehydration (search) in people with diabetes (search).
As heat waves become increasingly common—July 2024 was the hottest month ever recorded—healthcare professionals are raising awareness about an often-overlooked risk: many commonly prescribed and over-the-counter medications can significantly impair the body's ability to cope with extreme heat. These drugs can interfere with sweating, thermoregulation, cardiac output, thirst sensation, and fluid balance, placing patients at heightened risk for dehydration (search), heat exhaustion, and potentially life-threatening heat stroke (search).
"People are all aware of the risks of overheating, dehydration (search), and sunburn. But they should all be more aware of how medications can cause intolerance to summer heat," said David Cutler, MD, board certified family medicine physician at Providence Saint John's Health Center in Santa Monica, CA.
How Medications and Heat Interact
The human body manages heat through three primary mechanisms: sweating to cool the skin, shifting blood flow to the skin, and adjusting heart rate and blood pressure to maintain steady circulation. Certain medications can disrupt one or more of these processes, while others increase dehydration (search), making it harder to cool down and potentially compromising kidney function.
According to the Centers for Disease Control and Prevention (search) (CDC), medications can contribute to heat sensitivity through reduced thirst sensation, interference with thermoregulation, impaired sweating, reduced cardiac output, electrolyte imbalance, and cognitive impairment.
Cardiovascular Medications: Diuretics, Beta-Blockers, and ACE Inhibitors
Diuretics, commonly referred to as "water pills" and exemplified by furosemide (Lasix), are frequently used to control blood pressure or reduce swelling. In extreme heat, these medications increase urination, leading to dehydration (search) and electrolyte imbalances, while also raising the risk of dizziness, fainting, and falls.
Beta-blockers such as metoprolol (Lopressor) reduce the body's ability to increase heart rate in response to heat stress. The American Heart Association notes that these medications can exaggerate the body's reaction to heat, impairing thermoregulation and elevating core body temperature.
ACE inhibitors like lisinopril (Zestril) and ARBs like losartan (Cozaar) can contribute to dehydration (search), affect kidney function, and reduce thirst sensation, making patients less likely to hydrate adequately. The risk is compounded when these drugs are combined with a diuretic.
Mental Health Medications: Antidepressants, Antipsychotics, and Stimulants
Antidepressants can disrupt typical sweating patterns, potentially leading to either hyperhidrosis (excessive sweating) or anhidrosis (reduced sweating). Research from 2022 noted that certain antidepressants can raise core body temperature to 106°F (41°C), increasing the risk of heat exhaustion and heatstroke.
SSRIs like sertraline (Zoloft) may increase sweating, raising dehydration (search) risk, while tricyclic antidepressants such as amitriptyline (Elavil) may decrease sweating, making it harder to cool down. Antipsychotic medications like quetiapine (Seroquel) can interfere with temperature regulation and sweating.
Lithium presents a particular concern: dehydration (search) can lead to drug toxicity, with warning signs including dizziness, tremors, unsteadiness, lethargy, slurred speech, and confusion. Patients experiencing these symptoms should contact a healthcare professional immediately.
Stimulant medications used to treat ADHD, such as methylphenidate (Ritalin), increase metabolic activity and can raise heat production, making it easier to overheat during outdoor activity, especially when hydration and rest breaks are inadequate.
Allergy and Sleep Medications
Over-the-counter medications also warrant caution, particularly older antihistamines like diphenhydramine (Benadryl). These drugs can reduce sweating, cause drowsiness that masks early heat illness symptoms, and increase the risk of overheating.
Diabetes (search) Medications and Heat: A Complex Interaction
Diabetes (search) itself can affect sweat glands and the body's ability to cool itself, while also increasing dehydration (search) risk. During heat waves, dehydration and heavy sweating can raise blood glucose levels and impair the kidneys' ability to clear excess sugar. High temperatures can alter subcutaneous insulin absorption and glucose utilization, leading to unpredictable highs and lows. People with diabetic autonomic neuropathy may have impaired heat regulation, further increasing the risk of heat exhaustion and heat stroke (search).
SGLT2 inhibitors such as empagliflozin (Jardiance) may worsen dehydration (search). GLP-1 receptor agonists like semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro) suppress natural thirst cues, delay stomach emptying, and can cause nausea—all of which may lead to reduced fluid intake and increased dehydration risk. These medications may also lower blood pressure in some individuals, leading to dizziness and fainting that can be compounded by warmer weather.
Metformin may make it more difficult to recognize the signs of dehydration (search) and, while rare, can increase the risk of lactic acidosis, especially in people with kidney issues, potentially due to severe dehydration.
The CDC suggests that people with diabetes (search) may need to test their blood sugar levels more often in warmer weather and may need to adjust their insulin dose, diet, and fluid intake accordingly. Extreme heat can also impair glucose monitoring devices, and insulin can lose potency if not stored according to directions.
Anticonvulsant Medications
Certain anticonvulsant medications, including zonisamide and topiramate, may reduce the amount a person sweats. Older research indicates this effect may be more pronounced in children, and people taking these medications should avoid heat and humidity as much as possible.
Warning Signs and Safety Recommendations
Common warning signs of heat stress include dizziness or lightheadedness, fatigue or weakness, intense thirst, reduced urination, and nausea. Emergency signs that warrant an immediate 911 call include confusion, fainting, severe headache, or hot, dry skin—potential indicators of heat stroke (search).
Signs of dehydration (search) may include fatigue, low urine output, dark-colored urine, dry skin or cracked lips, headache, dizziness or light-headedness, heart palpitations, low blood pressure, and altered mental status or poor concentration.
Experts emphasize that patients should never stop medications on their own. Instead, they should contact their doctor or pharmacist to discuss whether a personalized "hot day plan" is needed. Key safety measures include staying cool, drinking plenty of water, and seeking medical help promptly if symptoms of heat-related illness develop.