Summer Medicine: Your Pill Bottle Has Heat Warnings

There is a drawer in my Valletta apartment — I pass it every morning — where I keep things I haven't decided what to do with yet. A ring. A postcard from Geneva. And, from years of moving between climates, a habit of reading the small print on medication packaging that most people throw away without looking.

July in Valletta is not a metaphor. It is thirty-seven degrees on the stone streets and the light comes off the harbour like something physical, something that pushes back. I think about this every summer when the European heat alerts begin to move across my screen, because heat is not just uncomfortable — it is pharmacological. What you take changes how your body responds to temperature, and almost nobody tells you this at the pharmacy counter.

The GLP-1 conversation has been everywhere this year — Ozempic, Wegovy, Mounjaro — and most of it has focused on weight and blood sugar and cardiovascular benefit, which are real and documented. What gets less airtime is the more immediate concern for anyone living through a Mediterranean or British summer on these medications: they suppress thirst. Not dramatically, not in a way you'd necessarily notice, but enough that your body's early-warning system for dehydration becomes quieter than it should be. You feel fine until you don't. By the time you're thirsty on a GLP-1 in heat like this, you're already behind.

It's not only GLP-1s. Diuretics, antihistamines, certain antidepressants, beta-blockers — all of them alter thermoregulation in different ways, either by reducing sweating, affecting blood flow to the skin, or blunting the neurological signals that tell you to slow down and find shade. The body's cooling system is more sophisticated than we treat it, and it is also more easily interrupted.

None of this is reason for alarm. It is reason for attention, which is a different thing entirely. If you are on any regular medication — particularly anything for blood pressure, mood, allergies, or metabolic health — a five-minute conversation with your pharmacist or GP before a heatwave is not overcaution. It is basic maintenance, the kind of thing that doesn't make headlines but keeps people out of emergency rooms.

Drink water before you are thirsty. This sounds obvious until you understand that thirst is a lagging indicator, not a leading one — by the time the signal arrives, the deficit is already there.

One thing to do: Pull out whatever medication you take regularly and search the name alongside "heat" or "thermoregulation." Read what comes up. Then drink a glass of water.