Heatwaves are becoming more frequent, intense, and prolonged in Europe, creating a predictable clinical stressor for multimorbid patients and increasing pressure on Internal Medicine services. Current disease-specific guidelines provide limited practical guidance on how to prevent heat-related admissions and decompensations in patients exposed to polypharmacy, frailty, chronic kidney disease, heart failure, diabetes, cognitive impairment, or social vulnerability. This Editorial proposes the concept of thermopharmacological frailty, a dynamic state in which environmental heat modifies the risk–benefit balance of chronic medication by impairing thermoregulation, hydration, renal perfusion, cardiovascular compensation, cognition, and metabolic stability.
