A heat wave can be dangerous for anyone, but some everyday prescription and over-the-counter medications can make it harder for the body to handle high heat, increasing the risk of dehydration, dizziness, fainting, and heat illness.
Below are several medication classes that are especially important to consider during hot, humid weather.
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Do not stop any medication on your own. If you’re concerned, call your doctor or pharmacist and ask whether you need a “hot day plan.”
Why heat and medications can be a risky mix
Your body is always producing heat. In hot weather, it has to get rid of that heat by:
- Sweating (to cool the skin)
- Shifting blood flow to the skin
- Adjusting heart rate and blood pressure to keep circulation steady
Some medications can interfere with one or more of those processes.
Others can increase dehydration, making it harder to cool down and affecting kidney function.
Diuretics (“water pills”)
Diuretics are commonly used to control blood pressure or reduce swelling. A well-known example is Lasix.
In extreme heat, diuretics can:
- Increase urination, leading to dehydration
- Contribute to electrolyte imbalances
- Raise the risk of dizziness, fainting, and falls
Blood pressure and heart medications
Beta blockers
Beta blockers—such as Lopressor—can reduce your ability to increase your heart rate in response to heat stress.
They also lower blood pressure, which can make some people more prone to lightheadedness or fainting in the heat.
ACE inhibitors and ARBs
ACE inhibitors like Zestril and ARBs like Cozaar are also widely used to treat high blood pressure.
During a heat wave, these medications can:
- Contribute to dehydration, especially if you aren’t drinking enough fluids
- Affect kidney function
- Reduce thirst, so you may be less likely to hydrate
Risk can be higher when these drugs are combined with a diuretic.
Mental health medications
Some mental health medications can affect sweating and the body’s temperature control.
Antipsychotics
Antipsychotic medications like Seroquel can interfere with temperature regulation and sweating.
SSRIs
SSRIs—like Zoloft—may increase sweating, which can increase the risk of dehydration.
Tricyclic antidepressants (TCAs)
TCAs—like Elavil—may decrease sweating, making it harder to cool down.
Stimulant medications used to treat ADHD
Stimulants, such as Ritalin, increase metabolic activity and can raise a person’s heat production.
That can make it easier to overheat during outdoor activity, especially if hydration and breaks aren’t adequate.
Allergy and “PM” sleep medicines
Over-the-counter medications can matter too, especially older antihistamines like diphenhydramine, best known by the trade name Benadryl.
These medications can:
- Reduce sweating
- Cause drowsiness, which can make it harder to recognize early heat illness symptoms
- Increase the risk of overheating
Diabetes and heat: extra risks for blood sugar control
Diabetes—and the medications used to treat it—deserve special attention during extreme heat.
In a heat wave:
- Dehydration and heavy sweating can raise blood glucose levels and make it harder for the kidneys to clear excess sugar.
- High temperatures can alter subcutaneous insulin absorption and the rate at which the body uses glucose, leading to unpredictable highs and lows.
- People with diabetic autonomic neuropathy may have impaired heat regulation, increasing the risk of heat exhaustion and heat stroke.
Some medications can add to the risk:
- SGLT2 inhibitors (example: Jardiance) may worsen dehydration.
Also, heat can affect devices and storage:
- Extreme heat can impair glucose monitoring devices.
- Insulin can lose potency if it’s left in heat or not stored according to directions.
GLP-1 drugs for diabetes and weight loss
GLP-1 drugs—like Ozempic—can increase the risk of heat problems for some people. That may be related to reduced thirst, slower digestion, which can contribute to dehydration, and changes in how the body regulates temperature.
Warning signs to watch for
Call a healthcare provider if you’re concerned, and seek emergency help if symptoms escalate.
Common warning signs of heat stress include:
- Dizziness or lightheadedness
- Fatigue or weakness
- Intense thirst
- Reduced urination
- Nausea
Emergency signs can include confusion, fainting, severe headache, or hot, dry skin. If you suspect heat stroke, call 911 immediately.
Quick safety tips during a heat wave
- Don’t stop medications without medical guidance.
- Ask your doctor or pharmacist about a “hot day plan.”
- Hydrate early and often (follow your provider’s guidance if you have fluid restrictions).
- Avoid peak heat; take frequent breaks in shade or air conditioning.
- Store medications properly—don’t leave them in a hot car, delivery box, or sunny window.