Have you ever felt weak, dizzy, or suddenly unwell in the heat while taking a prescription medication? It's easy to blame the temperature or a skipped breakfast. But sometimes the real culprit is sitting right in your medicine cabinet.
Your body has its own built-in cooling systems — sweating, adjusting blood flow to the skin, and keeping fluids in balance. The problem is, these mechanisms don't always work the way they should when certain medications get in the way. According to a summary from the science outlet The Conversation, several types of drugs can increase the risk of heat-related illness, especially in older adults and people living with chronic conditions.
Antidepressants
Some of the most commonly involved medications are antidepressants — particularly selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs). These drugs affect the hypothalamus, the part of the brain responsible for regulating body temperature, and can disrupt or block the signals that would normally trigger sweating.
The result? You may find it harder to sweat — or, in some cases, you might sweat far too much — and in hot weather, either extreme puts extra strain on your body.
Antipsychotics
Antipsychotics, used to treat schizophrenia or bipolar disorder, carry a different kind of risk. Because these medications block the effects of dopamine, the brain has a harder time recognizing when you're overheating or thirsty.
That can lead to reduced sweating, low blood pressure, and impaired heat release — exactly the conditions that set the stage for heatstroke.
Heart medications
People living with cardiovascular problems are also more vulnerable to feeling unwell in summer. Beta-blockers, prescribed for conditions like heart failure or high blood pressure, slow the heart rate, while diuretics increase urine output — together raising the risk of dehydration.
And dehydration on its own can amplify a medication's side effects, such as a drop in blood pressure or dizziness.
Insulin
For people with diabetes, heat brings even more risks. Warm temperatures cause blood vessels to dilate, which means insulin is absorbed more quickly — and that can trigger a sudden drop in blood sugar.
Hypoglycemia — low blood sugar — comes with symptoms like sweating, dizziness, confusion, and trembling, which are easy to mistake for signs of sun exposure. It's also worth knowing that heat itself can damage insulin: leave it in a hot car or fail to keep it cool, and it can lose its effectiveness.
How to protect yourself
The first step in avoiding summer illness is to always store your medications exactly as instructed. Insulin, for example, needs to be kept refrigerated — and the same may apply to other heat-sensitive products, such as inhalers or an EpiPen.
Staying properly hydrated is just as important. In summer, pay extra attention to drinking enough water — unless, of course, your doctor advises otherwise. Dehydration can intensify medication side effects, and with certain drugs — like lithium or anti-inflammatories — it can even become dangerous.
It also helps to avoid the hottest part of the day whenever possible and stay in the shade or somewhere cool. If you notice dizziness, nausea, confusion, or excessive sweating, rest immediately, cool yourself down, and replace fluids.
And finally: never stop taking your medication without medical advice. If you're worried about how the heat might affect you alongside your treatment, talk to your doctor or pharmacist.
Which medications are most affected by heat?
Antidepressants (especially SSRIs and tricyclics), antipsychotics, beta-blockers, diuretics, and insulin are among the most commonly involved. Each can interfere with how your body regulates temperature or fluid balance.
Why does heat feel worse when I'm on certain medications?
Some drugs disrupt sweating, blood flow, or the brain's ability to sense overheating and thirst. This makes it harder for your body to cool itself, so the heat affects you more strongly.
How can I protect myself during hot weather?
Store medications as instructed, keep heat-sensitive ones like insulin cool, stay well hydrated, avoid the hottest hours of the day, and rest in a cool place if you start feeling unwell.
Should I stop my medication in summer?
No. Never stop taking a prescribed medication without speaking to a professional first. If you have concerns about the heat, discuss them with your doctor or pharmacist.
