Medication and Heat Illness: How Drugs Affect Your Body in High Temperatures

When it gets hot, your body works harder to cool down—but if you're taking certain medication, a substance taken to treat, prevent, or manage a health condition, that process can go wrong. Heat illness isn’t just about sweating too much; it’s about your body losing its ability to regulate temperature, and many common drugs interfere with that. Whether it’s a blood pressure pill, an antidepressant, or even an over-the-counter allergy med, some medications block your sweat, raise your core temperature, or make you dehydrated without you realizing it. This isn’t rare—it happens every summer, and it’s often preventable.

People on diuretics, drugs that increase urine output to reduce fluid buildup are at higher risk because they lose more water and salt, making it harder to stay cool. Anticholinergics, medications that block acetylcholine to reduce muscle spasms or secretions, found in some bladder and motion sickness drugs, shut down sweat glands entirely. Even antidepressants, drugs used to treat mood disorders like depression and anxiety, can mess with your body’s thermostat. A study from the CDC found that over 1,000 heat-related hospital visits each year in the U.S. are linked to people taking these kinds of drugs. You might not feel dizzy or thirsty until it’s too late. That’s why knowing your meds’ side effects isn’t just smart—it’s lifesaving.

It’s not just about the drug itself. Combining meds with heat, alcohol, or physical activity multiplies the danger. Someone on a blood pressure med might feel fine walking the dog in the morning, but if they’re also drinking a beer and wearing dark clothes, their body can’t compensate. The same goes for older adults on multiple prescriptions—they’re often more sensitive to heat and less aware of early warning signs like confusion, nausea, or a racing pulse. The good news? You don’t have to stop your meds. You just need to know how to adjust. Drink water before you feel thirsty. Avoid the sun between 10 a.m. and 4 p.m. Wear light clothes. Check with your pharmacist or doctor if your meds are on the high-risk list. And if you’re caring for someone older or on chronic meds, watch for subtle changes. Heat illness doesn’t always come with a warning siren. Sometimes, it just creeps in quietly.

Below, you’ll find real-world guides on how specific drugs interact with your body’s heat response, what to watch for, and how to protect yourself without giving up your treatment plan. These aren’t theory pieces—they’re practical checks from people who’ve been there, and the data behind them.