Case study

10/12/25

10 December 2025

Managing heat-related health risks in acute care

Green Physician Toolkit Illustrations 12

Practical guidance to protect patients and staff during extreme heat events, embedding resilience into routine care.

The issue

  • Heat is a major and growing health risk:
  • Rising temperatures are causing increasing morbidity and mortality, particularly among vulnerable groups such as older adults and those with comorbidities.
  • In 2022, there were 2,985 deaths in England and Wales due to extreme heat.
  • There has been an 85% increase in heat-related mortality globally in 2017–21 vs 2000–04, according to the World Health Organization. Heat-related illness can be under-recognised and often mimics other conditions, which increases the risk of delayed or inappropriate treatment.

The solution

With the significant heat-related risks already present in the UK, healthcare must proactively adapt to respond effectively if these risks worsen.

Having identified the problem, the Society for Acute Medicine’s ecoSAM Working Group have developed a hot weather guide that is being used to support clinicians to manage risks and deliver safe, effective treatment during hot weather.

Examples in the guidance include medication reviews (eg diuretics, insulin), ensuring safe storage of drugs, and staff wellbeing measures such as flexible uniform policies and hydration breaks. These changes can be embedded into local trust policies to build resilience.

The impact

The benefits of managing heat-related risks in acute care are multifaceted. Although we need a long-term solution to climate change, we must mitigate risk with the impact highlighted below:

  • For patients – reduced iatrogenic harm, earlier recognition of heat illness, improved safety.
  • For staff – wellbeing support, safer working conditions, clear clinical guidance.
  • For healthcare systems – improved preparedness, reduced admissions, alignment with sustainability goals.

Conclusion

Effective heat mitigation in healthcare is both a patient safety issue and a sustainability issue. By embedding practical guidance into routine practice, we can protect patients, safeguard staff, and reduce the system-wide burden of extreme heat events.

Contributors: Dr Beth Griffith and Dr Jamie Phillips

Institutions: Mid Cheshire Hospitals NHS Foundation Trust | Society for Acute Medicine’s ecoSAM Group

Policy

policy@rcp.ac.uk

Case examples

An 82-year-old woman with heart failure with reduced ejection fraction presented feeling generally unwell during a heatwave. She reported light-headedness, nausea and marked thirst. She was found to have postural hypotension, hyponatraemia, hypokalaemia and an acute kidney injury. Diuretics were suspended, IV fluids were given with frequent clinical volume assessments, and she improved.

Impact of hot weather: Hot weather increased insensible fluid loss, causing dehydration, electrolyte disturbance, reduced renal perfusion, and potentiated the effects of her diuretics and RAAS inhibitors. Frail, older adults are particularly vulnerable due to impaired thirst response and limited physiological reserve.

What to do:

  • Encourage proactive hydration and clear sick-day rules for diuretics/RAAS blockers.
  • Educate on early symptoms of heat-related illness and when to seek help.
  • Review ‘culprit’ drugs in hot weather (diuretics, SGLT2 inhibitors, anticholinergics).
  • Identify at-risk patients and provide anticipatory guidance before heatwaves.
  • Incorporate medication heat-risk flags into routine reviews.
  • Provide community messaging and coordinate with heart-failure services during heat alerts.

A 35-year-old man with Type 1 Diabetes on an insulin pump had attended a festival during a heatwave. He reported vomiting and abdominal discomfort, which he had initially attributed to alcohol consumption but subsequently had rising glucose and became progressively drowsy. He presented with hyperglycaemia and marked ketosis, consistent with diabetic ketoacidosis (DKA).

Impact of hot weather: Heat exposure led to significant fluid losses, reducing circulating volume and impairing insulin absorption. Heat stress increased counter-regulatory hormones, driving hyperglycaemia and ketogenesis. Vomiting and reduced intake caused further insulin omission. Hyperthermia was initially mistaken for infection, delaying recognition of metabolic decompensation.

What to do:

  • Reinforce sick-day rules tailored to hot-weather.
  • Emphasise frequent checking of glucose and ketones during heatwaves.
  • Encourage carrying backup hydration, pump supplies and cooling strategies at events.
  • Recognise dehydration as a primary precipitant of DKA in heatwaves.
  • Provide targeted messaging to people with diabetes during hot weather alerts.
  • Differentiate heat illness from infective triggers to avoid diagnostic delay.

A 26-year-old psychiatric inpatient developed agitation, confusion and persistent hyperthermia (40.1°C). She was transferred to a local emergency department and was initially treated for meningitis, after leukocytosis and acute kidney injury was noted. Meningitis was subsequently excluded following a lumbar puncture. She was ultimately diagnosed with drug-induced hyperthermia, likely exacerbated by lisdexamfetamine and bupropion during a period of extreme heat. Her temperature and mental state normalised after medication withdrawal and cooling measures.

Impact of hot weather: Heat amplified the thermogenic effects of psychotropic medications and stimulants. Hyperthermia risk is higher in psychiatric inpatients due to impaired self-monitoring, possible restricted access to fluids, and reduced capacity to seek cooler environments. Serotonergic or dopaminergic agents can mask or mimic heat illness.

What to do:

  • Monitor temperature, agitation and medication side effects more closely during heatwaves.
  • Review stimulant/serotonergic agents if heat-related symptoms develop.
  • Consider psychiatric medications in patients with hyperthermia.