Heat Stroke and Dehydration: Signs, First Aid and Prevention

6 min read · Conditions · By the Asthra Health Care team

Heat illness in India

During the summer months, especially from March to June, temperatures in Karnataka and Andhra Pradesh can climb very high, and heat waves are becoming more frequent. The body cools itself mainly by sweating. When it is very hot or humid, or when a person loses too much fluid, this cooling system can fail.

Heat illness ranges from mild dehydration and heat cramps to heat exhaustion and, at the most serious end, heat stroke. Recognising the early signs and acting quickly prevents the more dangerous stages. High humidity makes things worse, because sweat does not evaporate well, so even moderate temperatures can be risky on humid days.

Dehydration and heat exhaustion

Dehydration happens when the body loses more water and salts than it takes in, through sweating, vomiting or loose motions. Heat exhaustion is the next step, when the body is struggling to cope with heat. The person is still usually alert and sweating.

• Thirst, dry mouth and dark yellow urine
• Passing less urine
• Headache, dizziness and tiredness
• Heavy sweating, cool clammy skin
• Muscle cramps, nausea or vomiting
• Fast pulse and feeling faint

Heat stroke: a medical emergency

Heat stroke occurs when the body temperature rises very high and the brain's temperature control fails. It can damage the brain, kidneys, liver and heart, and can be fatal. It can develop quickly, sometimes without earlier warning signs, in people working or exercising in the sun.

Key signs include very high body temperature, hot skin that may be dry or sweaty, confusion, slurred speech, strange behaviour, fits, fainting or unconsciousness. Any person in the heat who becomes confused or collapses should be treated as having heat stroke until proven otherwise. Call an ambulance (108) at once.

First aid

For heat exhaustion, move the person to a cool, shaded place, loosen tight clothing, and let them lie down with legs slightly raised. Give sips of ORS, water or buttermilk if they are alert. Cool the skin with a wet cloth and a fan. They should start to improve within about half an hour; if not, get medical help.

For heat stroke, call for emergency help and start cooling immediately while waiting. Move the person to shade, remove extra clothing, pour or spray cool water over the body and fan them continuously. Place ice packs or cold wet cloths in the armpits, neck and groin. Do not give fluids by mouth if the person is confused or unconscious.

Treatment and medicines

Mild dehydration is treated with oral rehydration solution and rest. In hospital, heat stroke is treated with rapid cooling, intravenous fluids and close monitoring of organs. Blood tests check kidney function, salts, blood sugar and muscle damage. Even after recovery, a person who had heat stroke should rest and avoid heat for some time, as advised by the doctor.

Fever medicines such as paracetamol do not lower the high temperature of heat stroke and should not be relied on. People taking water tablets (diuretics), blood pressure medicines or some psychiatric medicines are more vulnerable to heat; they should ask their doctor for advice before summer and must not stop these medicines on their own.

Who is at higher risk?

Infants and young children, elderly people, pregnant women, outdoor workers, farmers, traffic police, construction workers, athletes and people with heart disease, kidney disease, diabetes or obesity are at higher risk. Older people may not feel thirsty even when dehydrated. Never leave children or elderly people in a parked car, even for a few minutes.

Prevention and when to see a doctor

Drink water regularly through the day, even before you feel thirsty. Include buttermilk, lemon water with a pinch of salt, tender coconut water and ORS on very hot days, and limit alcohol, tea, coffee and sugary drinks. Avoid outdoor work and exercise between noon and about 3 pm. Wear loose, light-coloured cotton clothes, a hat or umbrella, and keep homes cool with shade and cross-ventilation.

Check on elderly neighbours during heat waves and follow local heat alerts. See a doctor for dehydration that does not improve with fluids, and get emergency help for signs of heat stroke. Your doctor or pharmacist can advise if your regular medicines need extra care in summer.

This article is general health information, not medical advice. Do not start, stop or combine medicines on your own — always follow your doctor's prescription and ask your pharmacist if unsure.