As climate change accelerates extreme heatwaves are becoming more frequent and severe posing significant threats not only to human health but also to the capacity of healthcare systems to function effectively. While the direct effects of heat on conditions like heatstroke kidney damage, and cardiovascular stress are well documented, new research highlights a less visible but equally dangerous consequence hospital congestion and compromised patient care during heat-driven surges in demand.
A recent study by Aguilar-Gomez et al. (2025) examines how extreme heat disrupts healthcare systems, using data from Mexico, where healthcare resources are often stretched thin and the frequency of heatwaves is expected to rise disproportionately compared to higher-latitude countries. Their findings reveal that when temperatures exceed 34°C, emergency department visits increase by 7.5%, while hospital admissions rise by 4%.
The increased demand forces hospitals to ration care, often discharging patients earlier than usual to free up beds. Alarmingly, those discharged on extreme heat days are often in poorer health compared to patients released under normal conditions, raising concerns about post-discharge mortality and preventable deaths.
The study also finds that hospital overcrowding during heatwaves leads to higher mortality rates even among patients already hospitalised before a heatwave begins. Researchers isolated the impact of congestion by analyzing deaths among cancer patients, a group not physiologically vulnerable to heat exposure. Their findings suggest that excess mortality during extreme heat events is driven more by overcrowded and overwhelmed hospitals than by direct temperature effects.
This growing crisis underscores the urgent need for healthcare systems to adapt to the challenges posed by climate change. While discussions on climate adaptation often focus on air conditioning, urban planning, and transportation resilience, the healthcare sector remains a critical yet under-addressed area. Strengthening hospital infrastructure, expanding workforce capacity, and implementing surge management protocols during extreme heat events are crucial steps to prevent unnecessary deaths and ensure that healthcare systems remain functional in a warming world.
The stakes are particularly high for developing countries, where access to air conditioning is limited, and healthcare facilities are already overburdened. Investing in hospital resilience improving patient triage and enhancing coordination between medical facilities could play a vital role in mitigating both the direct and indirect health effects of climate change.
As policymakers and healthcare leaders prepare for an increasingly extreme climate ensuring that hospitals remain equipped to handle surging patient volumes will be essential. Without urgent action, rising temperatures will not only threaten lives directly but will also strain healthcare systems to a breaking point, exacerbating health disparities and increasing the risk of preventable deaths.