Every summer I notice the same thing. People arrive at the clinic tired
headachy a little off. They assume it's stress or poor sleep or too much screen time. And sometimes those things are true. But quite often the real explanation is simpler and more urgent they're overheated, and they don't know it.
Heat exhaustion is easy to miss because its early signs are vague. A dull headache. Feeling irritable or slightly dizzy. Nausea. Urinating less than usual. These are the body's first signals that the thermoregulatory system is struggling. And in a warm apartment without air conditioning, or after an afternoon in the sun, they can come on faster than most people expect.
What I want to share this week is what actually happens in the body during heat stress and what the 2025 data tells us about how serious the situation in Europe is becoming.
Which pattern do you notice most in your own body?
This is no longer a minor seasonal inconvenience
This is no longer a minor seasonal inconvenience
A study published by researchers from the London School of Hygiene and Tropical Medicine in September 2025 found that climate change drove an estimated 16,500 additional deaths across 854 European cities during the summer of 2025 alone. Climate change was responsible for around 68% of the 24,400 estimated heat-related deaths that summer. People aged 65 and over made up 85% of those deaths.
The WHO puts the longer-term picture into context between 2000 and 2019, approximately 489,000 heat-related deaths occurred globally each year, with 36% in Europe. Heat-related mortality in people over 65 increased by approximately
85% between 2000–2004 and 2017–2021. These are not distant projections this is already happening.
Europe is the fastest-warming continent on the planet. And as the proportion of people over 65 in the EU rises — from 21.6% today toward 32.5% by 2100 the intersection of an aging population and intensifying summers is one of the most pressing public health challenges we face.
85%Increase in heat-related mortality in people over 65 between 2000–2004 and 2017–2021. Source: WHO, 2026.
The Pattern Underneath Every Pattern
What happens inside the body and when it becomes dangerous
Heat exhaustion and heatstroke are points on the same continuum. In heat exhaustion the body is struggling but still compensating sweating heavily, heart rate rising, blood pressure dropping. The symptoms are nonspecific: malaise, headache, nausea, weakness. Critically, sweating may stop, which is a dangerous sign that things are escalating.
Heatstroke is a different category entirely. It's defined by a core body temperature above 40°C combined with central nervous system dysfunction confusion, disorientation, slurred speech, seizures, or loss of consciousness. At this point the body's thermostat has failed. This is a medical emergency. Without immediate cooling it can progress to multi-organ failure the liver, kidneys, and heart can all be affected and death.
The single most important intervention in heatstroke is immediate cooling not waiting for the ambulance. Cold water immersion or evaporative cooling should start the moment heatstroke is suspected. Every minute matters delays in cooling directly worsen outcomes.
For cooling at home a shower at 17–20°C is effective not ice cold which can cause blood vessels to contract and actually slow cooling. A wet towel on the neck and armpits works well. A fan combined with water misting is highly effective. Get to a cool room immediately.
The single most important intervention in heatstroke is immediate cooling not waiting for the ambulance. Cold water immersion or evaporative cooling should start the moment heatstroke is suspected. Every minute matters delays in cooling directly worsen outcomes.
The groups that need the most attention
Small children cannot regulate their temperature as efficiently as adults and can't always communicate that they're struggling. In a hot car, a pram in direct sun, or a warm room with poor ventilation, their core temperature can rise frighteningly fast.
Older adults particularly those over 65 have reduced sweating capacity and a diminished sense of thirst. They may not feel hot until they're already significantly dehydrated. Those with heart disease, kidney disease, or diabetes are at higher risk because these conditions affect circulation and fluid balance. And people with dementia or cognitive impairment often can't recognise or communicate that they're overheating they need someone checking on them.
Medications are an underappreciated risk factor. Diuretics, beta-blockers, certain blood pressure medications, and some antidepressants can impair the body's ability to regulate heat or increase fluid loss. If you or someone you care for takes these, the risk during a heatwave is meaningfully higher. Talk to a doctor before summer about whether any medications need to be reviewed.
Practical steps before during and after
Drink before you feel thirsty. By the time thirst kicks in you're already behind. Aim for consistent intake through the day pale yellow urine is the best simple indicator that you're adequately hydrated. Avoid alcohol and excess caffeine in high heat both are dehydrating.
Keep the home cool by closing windows and drawing curtains during the hottest part of the day typically between 11am and 4pm. Open windows in the evening when outside air becomes cooler than indoor air. Lightweight loose clothing and a hat outdoors make a real difference.
Eat lighter meals. When we eat large meals, blood circulation shifts from the skin where it helps with cooling toward the digestive system. Smaller more easily digested meals keep more circulation available for temperature regulation.
Check on vulnerable people. An elderly neighbour, a relative with dementia, a friend on multiple medications a brief check-in during a heatwave can be life-saving. They may not reach out themselves.
If someone is confused has stopped sweating despite the heat has hot dry skin or is losing consciousness call emergency services immediately and begin cooling without waiting.
If someone is confused, has stopped sweating despite the heat, has hot dry skin, or is losing consciousness call emergency services immediately and begin cooling without waiting.
One more thing from clinic
Every summer I see the same pattern. People arrive tired, headachy and dehydrated and their neck and back symptoms are often worse. Most don't connect it to the heat.
Heat stress can contribute to fatigue, headache and muscle soreness, especially in older adults and those who become dehydrated.
That's why, as a chiropractor, heat is very much my topic too.
If you're looking for electrolyte support, I've reviewed several options for patients and you can find my current recommendations here.
If you want electrolyte support I have looked into for patients use my link for 20% off
Advertisement. Not medical advice, consult your doctor before starting any supplement.
"There is a certain peace that comes with knowing less and choosing better."
Until the next signal,
Dr Erik Rudberg
Chiropractor
Most people wait for pain. The attentive ones notice the signal.
