As temperatures climb, the risk of heat-related illnesses increases—especially for people taking certain prescription medications. Some drugs interfere with how the body cools itself, making it more difficult to cope with hot weather.
The human body relies on three main processes to regulate temperature: sweating, blood flow to the skin, and fluid balance. But certain medicines can disrupt these systems. Here are five types of prescription drugs that may increase heat sensitivity:
1. Antidepressants
Certain antidepressants, such as selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs), can make it harder to cool down.
These medications affect brain chemicals like serotonin and noradrenaline. TCAs, in particular, can block a chemical called acetylcholine, which plays a role in sweating. Less sweating means the body may not be able to release heat efficiently on hot days.
On the other hand, both SSRIs and TCAs may also increase sweating in some people—up to 14% of users report this side effect. However, excessive sweating without proper hydration can lead to dehydration, which further increases the risk of heat exhaustion or heatstroke.
SSRIs might also interfere with the hypothalamus—the brain’s temperature control center—reducing its ability to signal the body to sweat.
2. Antipsychotics
Drugs used to treat conditions like schizophrenia and bipolar disorder can also raise heat risk. Antipsychotics work by blocking dopamine, which influences serotonin and affects the hypothalamus’s ability to manage body temperature.
As a result, people taking these medications may not feel hot or thirsty, even in high heat. Their body may react by narrowing blood vessels and retaining heat. This can reduce sweating and increase the danger of overheating.
Many antipsychotics also have anticholinergic effects, which block sweating altogether.
3. Heart Medications
Several heart medications affect how the body manages heat.
Beta-blockers, used for conditions like heart failure, lower heart rate and reduce blood flow to the skin. This can prevent heat from escaping the body.
Diuretics, commonly prescribed for high blood pressure, increase urine output. This can cause dehydration and make it harder to sweat.
Other drugs like ramipril and losartan affect how the body controls blood pressure, fluid levels, and thirst. These medications can reduce the natural urge to drink water, increasing the risk of dehydration during hot weather.
When you’re dehydrated, your blood pressure can drop quickly, especially when standing up. This may lead to dizziness or fainting.
4. Stimulants
Stimulants, such as those used to treat attention-deficit/hyperactivity disorder (ADHD), affect chemicals like dopamine and noradrenaline. These drugs can raise body temperature, speed up metabolism, and affect how the body sweats.
In hot weather or during physical activity, this can increase the risk of overheating or dehydration. Some users may also feel less tired while on stimulants, which can lead them to overexert themselves without realizing the danger.
Interestingly, a few studies have found that people with ADHD who take stimulants might actually have a lower risk of heat-related illness. Researchers think this might be due to factors like lower body weight and better hydration habits—but more research is needed.
5. Insulin
For people with diabetes, insulin can be affected by heat in two ways.
First, warm weather causes blood vessels to expand, which increases blood flow where insulin is injected. This means insulin enters the bloodstream faster, potentially lowering blood sugar more quickly than expected. This can cause hypoglycemia, or low blood sugar, leading to symptoms like dizziness, sweating, confusion, or even fainting.
Second, heat can damage insulin. If stored improperly, insulin may become less effective or unsafe to use. Signs of heat-damaged insulin include a change in color or cloudiness. Insulin should always be stored in a refrigerator before use—especially in summer.
How to Stay Safe
Older adults, people with chronic illnesses, and those taking multiple medications are especially at risk during heatwaves. But there are steps you can take to reduce the danger:
Store medications properly: Keep them away from heat. Don’t leave them in hot cars or on windowsills. Insulin, inhalers, and EpiPens are especially sensitive to temperature.
Stay hydrated: Unless your doctor says otherwise, drink plenty of water during hot days. Dehydration can increase the risks of side effects for many medications.
Avoid peak heat: Try to stay indoors or in shaded, cool places during the hottest part of the day. Use fans or air conditioning when possible.
Know the warning signs: Watch for symptoms of heat illness, such as dizziness, nausea, confusion, or excessive sweating.
Talk to your doctor: Don’t stop taking medication without medical advice. If you’re struggling with the heat, ask your doctor or pharmacist if your medication might be part of the problem.
Conclusion
Many prescription drugs can make it harder for the body to stay cool. By understanding how your medication affects your heat response, and by taking simple safety measures, you can better protect your health during the hottest months of the year.
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