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Understanding Heat Stroke: What You Need to Know
Heat stroke happens when the body's core temperature rises to dangerous levels and the normal systems that cool us down—sweating and increased blood flow to the skin—stop working. The result is that the body overheats, which can affect the brain and other organs.
Common causes include being exposed to high temperatures for a prolonged period of time. This can be particularly dangerous if there is high humidity, or a person is working or exercising in hot conditions without resting or drinking enough. It might also include rapid heat exposure for people who aren’t acclimatised.
Some medical conditions and certain medications can also affect the body's ability to thermoregulate.
Key symptoms of heat stroke to be aware of are:
- A very high body temperature (often above normal fever levels),
- Hot, dry skin and a flushed (red) face,
- Confusion or change in mental state,
- Slurred speech,
- Seizures,
- Dizziness,
- Headaches,
- Nausea (feeling sick),
- and loss of consciousness.
If you spot any of these signs, treat the situation as an emergency—heat stroke can progress rapidly.
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Who is at Risk? Identifying Vulnerable Groups
Heat stroke can affect anyone, but certain people are more vulnerable and need extra care when temperatures rise.
- Elderly individuals: Age-related changes in thirst perception, circulation and sweat production increase risk. Mobility issues and social isolation can make it harder to cool down.
- Children and infants: Young children do not regulate temperature as efficiently because the part of the brain which helps with temperature regulation does not mature until they are around 5. They can dehydrate quickly, especially in hot cars or poorly ventilated rooms.
- People with medical conditions: Certain medical conditions make people more vulnerable - things like heart disease, diabetes, respiratory conditions and neurological disorders can heighten risk.
- Some medications (for example, diuretics, antihypertensives, and some antidepressants) affect sweating or hydration. Always read the guidance and talk to your prescriber if you need any further information.
Knowing who’s at risk helps you plan. Some tips might be to check on elderly neighbours during heatwaves to make sure they are looking after themselves. If you are leaving the car, you should never leave children unattended in vehicles for any reason. Temperatures inside cars rise very quickly and can be really dangerous. Ensure workplaces have heat policies and monitoring for staff.
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Preventative Measures: Staying Safe in the Heat
Prevention is where most effort should go. Simple practical steps reduce the likelihood of someone developing heat stroke, and help to keep people comfortable and productive.
Hydration is vital. Always carry water on you when you are out and about. Ensure your young people take enough water with them to school. Drink regularly throughout the day—don’t rely on thirst alone.
If you are going to be taking part in high levels of activity, low-sugar electrolyte drinks can help to replace salts lost in sweat. Avoid drinking excessive alcohol and caffeine during heatwaves; both can increase dehydration.
- Clothing: Wear loose-fitting, light-coloured clothes made of breathable fabrics such as cotton or technical wicking materials. Wide-brimmed hats and UV sunglasses help protect from direct sun.
- Environmental awareness: Monitor weather warnings so you are aware of upcoming high temperatures (Met Office heat-health alerts in the UK), understand humidity’s impact. Stay in shaded areas during the heat of the day. If you are going to be in enclosed spaces, use fans, ventilation or air conditioning where possible.
- Schedule wisely: Try to confine outdoor work or exercise to cooler parts of the day—early morning or late evening. Introduce gradual acclimatisation for workers and athletes: shorter, less intense sessions for the first week of high heat.
- Rest breaks: Try to rest often and seek shade if the sun is strong. For manual labour, rotate tasks so no one person is continuously exposed to heat.
For businesses, a simple heat-risk checklist can be effective: assess tasks that involve heat exposure, provide water and shaded rest areas, train staff to recognise symptoms, and create a plan for rapid response. It’s good practice to brief teams at the start of a heatwave and record anyone who’s particularly vulnerable.
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What to Do When Someone is Experiencing Heat Stroke
Heat stroke is an emergency. If you suspect someone has heat stroke, act quickly and calmly. Immediate steps can reduce the risk of serious harm.
- Call 999 immediately for an ambulance if someone shows signs of heat stroke—confusion, loss of consciousness, seizures, or very high body temperature. Prompt professional care is essential.
- Move them to a cooler place—shade, an air-conditioned room or at least out of direct sun. Lay them down and loosen tight clothing.
- Cool the person down using whatever is available: remove excess clothing, sponge or spray with cool (not icy) water, use wet towels or sheets, and fan vigorously. Place cold packs or ice wrapped in cloth at the groin, armpits and neck to aid cooling.
- If the person is conscious and able to swallow, give sips of water. Don’t force fluids if they’re drowsy or vomiting. Do not give alcohol or very cold drinks in large gulps. If unconscious, do NOT give anything by mouth.
- Monitor breathing and consciousness. Be ready to start CPR if they stop breathing—call the ambulance services for guidance while you wait.
For exertional heat stroke (for example athletes or workers who collapse during activity), rapid cooling—ideally whole-body cold-water immersion—is recommended where available and safe. However, this should only be carried out by people who can do so safely without delaying emergency services.
Do not assume someone is merely sunburned or dehydrated if they appear disoriented. When in doubt, treat as heat stroke and get professional help.
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Key Differences
- Heat exhaustion shows heavy sweating
- Heat exhaustion is often below high levels
- Heat exhaustion is treatable with rest
- Heat exhaustion needs rest and fluids
Consequences of Misidentification- Heat stroke can lead to confusion
- Heat stroke has dangerously high temperature
- Heat stroke is a medical emergency
- Heat stroke requires immediate cooling
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Conclusion: Stay Ready, Stay Cool
Heat stroke is preventable and manageable if you know the risks and act quickly. Always keep water available during times of high heat. Plan activities around the heat so you avoid unnecessary exposure to heat at the hottest part of the day. Try to check on vulnerable people in your community, and train staff or household members to recognise symptoms.
If the worst happens and you suspect heat stroke, call 999, move the person to a cooler place, start cooling measures and monitor their condition until help arrives. Quick action saves lives.
If you’re responsible for a team or workplace, consider first-aid training tailored to heat-related emergencies. Safety First offers practical, hands-on courses that cover recognition, immediate response and workplace preparation—get in touch to arrange a session that suits your organisation’s needs.
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