Heat exhaustion and heatstroke: signs, first aid and prevention

Hot weather can make the body struggle to cool down. This article explains heat exhaustion and heatstroke, the warning signs, first aid, who is most at risk and how to stay safe in the heat. It draws on the NHS, MedlinePlus and the World Health Organization (WHO).

1. Introduction

The body normally cools itself by sweating. MedlinePlus explains that in very hot, humid weather sweating may not be enough, so body temperature can rise to dangerous levels and cause a heat illness ^[2]. WHO says heat stress is a leading cause of weather-related deaths, and that heatstroke is a medical emergency with a high case fatality rate ^[3].

WHO estimates that heat caused about 489 000 deaths a year worldwide between 2000 and 2019, and says deaths and hospital stays can happen on the same day or in the days after a hot spell. It adds that practical, often low-cost steps can save lives ^[3]. Knowing the signs and acting early helps protect you and the people around you.

2. Types of heat illness

MedlinePlus lists four main forms ^[2]:

• Heat rash: skin irritation from heavy sweating, more common in young children.
• Heat cramps: muscle pains or spasms, usually in the abdomen, arms or legs, during heavy exercise.
• Heat exhaustion: can follow several days in high temperatures without enough fluids. If not treated it can turn into heatstroke.
• Heatstroke: a life-threatening illness in which body temperature can rise above 41 degrees Celsius (106 degrees Fahrenheit) within minutes.

3. Signs and symptoms

The NHS lists these symptoms of heat exhaustion ^[1]:

• Tiredness, dizziness and headache
• Feeling or being sick
• Heavy sweating with pale, clammy skin
• Cramps in the arms, legs and stomach
• A high temperature and being very thirsty
• Feeling irritable

The NHS says these signs are often the same in adults and children ^[1]. Heatstroke signs include a very high temperature, hot skin without sweating, fast breathing and heartbeat, confusion and restlessness, seizures (fits) and loss of consciousness ^[1].

4. Who is most at risk

MedlinePlus says older adults, young children, and people who are sick or overweight are most at risk, and that some medicines and alcohol can raise the risk ^[2]. WHO adds that outdoor and manual workers and athletes are exposed through their work, and that people with poor housing or little access to cooling can be affected more ^[3]. WHO says heat can make heart, lung, mental health and diabetes-related conditions worse and can cause sudden kidney injury. It also notes that older adults, infants, young children, people with heart, lung or kidney conditions and people living alone are especially vulnerable ^[3]. The NHS asks people to check on children, older people and those with long-term conditions during hot weather ^[1].

5. First aid and treatment

For heat exhaustion, the NHS gives these steps ^[1]:

1. Move the person to a cool place.
2. Remove unnecessary clothing such as a jacket or socks.
3. Give plenty of water to drink. An isotonic sports drink or oral rehydration powder mixed with water can help replace salt lost through sweating.
4. Cool the skin by spraying or sponging with cool water and fanning. Cold packs wrapped in cloth under the armpits or on the neck also help.
5. Stay with them until they are better.

They should start to cool down and feel better within 30 minutes ^[1]. If they are still unwell after 30 minutes, the NHS says to call emergency help because this may be heatstroke. While waiting for help in heatstroke, the NHS advises wrapping the person in a cool, wet sheet or fanning and sponging with cold water. If they lose consciousness, place them in the recovery position, check breathing and tell the ambulance service ^[1].

6. Prevention and self-care

The NHS and WHO suggest these everyday steps ^{[1, 3]}:

• Drink fluids regularly. WHO suggests about one cup of water per hour and at least 2 to 3 litres a day.
• Wear light, loose clothing and use cool showers or a damp cloth on the skin.
• Avoid the sun between 11am and 3pm and avoid extreme exercise.
• Limit alcohol.
• Spend 2 to 3 hours a day in a cool place and use shade.
• Close curtains or shutters by day, and open windows after dark when it is cooler outside.
• Use electric fans only when temperatures are below 40 degrees Celsius, as WHO says fans can heat the body above that.

For children, WHO advises never leaving a child or animal in a parked vehicle even briefly, keeping them in the shade, and dressing them in light, loose clothing and wide-brimmed hats ^[3].

7. When to see a doctor

Heat exhaustion usually does not need emergency help if the person cools down within 30 minutes ^[1]. Get medical advice if you are struggling to treat it, or if symptoms are not improving. Call for emergency help if the person is still unwell after 30 minutes of resting in a cool place, being cooled and drinking, or has a very high temperature, hot skin that is not sweating, a fast heartbeat, fast breathing, confusion, a seizure or loss of consciousness ^[1]. Do not drive yourself to hospital ^[1]. In an emergency, call your local emergency number (112 in India, 911 in the United States).

8. Conclusion

Heat illness ranges from rash and cramps to heatstroke, which is an emergency. Cooling down early, drinking fluids, avoiding the hottest hours and checking on people at higher risk are practical ways to stay safe.