Heat Exhaustion Heatstroke

Overview

Heat exhaustion and heatstroke are heat illnesses. They happen when the body gets too hot and cannot cool itself well. Heat exhaustion is the milder form. Heatstroke is a medical emergency and needs help right away.

Heat illness is common in hot weather, during heatwaves, and during heavy exercise or outdoor work. It can also happen indoors in very hot rooms.

Anyone can be affected. People at higher risk include older adults, babies and young children, outdoor workers, athletes, people who are dehydrated, and people with long-term health conditions. Some medicines can also raise risk, so ask a pharmacist or healthcare provider if you are unsure.

Symptoms

Common symptoms

• Heavy sweating
• Cool, clammy skin
• Weakness or tiredness
• Dizziness or lightheadedness
• Headache
• Nausea or vomiting
• Muscle cramps
• Fast or weak heartbeat
• Feeling very thirsty
• Confusion or trouble thinking clearly can be a warning sign of worsening illness

Symptoms in children

• Fussiness or irritability
• Sleepiness or trouble waking
• Poor feeding or drinking
• Vomiting
• Fewer wet nappies or less urine
• Hot skin
• Confusion or unusual behavior
• Fainting or seizure — call emergency services

Symptoms in older adults

• Confusion or memory problems
• Dizziness or fainting
• Weakness
• Dry skin or less sweating than expected
• Fast pulse
• Feeling very tired
• Nausea
• Body temperature may not always seem very high, so do not rely on temperature alone

Causes

Main causes

• Being in hot weather or a hot room for too long
• Heavy exercise or physical work in heat
• Not drinking enough fluids
• Wearing too much clothing in hot conditions
• Being dehydrated before heat exposure
• Sudden exposure to heat without time to get used to it

Risk factors

• Being an older adult
• Being a baby or young child
• Having a long-term health condition, especially heart, kidney, or lung problems
• Taking some medicines that affect sweating or fluid balance
• Being overweight or very unfit
• Drinking too much alcohol
• Working or exercising outdoors
• Living in housing that is hard to keep cool
• Being alone during hot weather

When to see a doctor

See a doctor urgently if:

• Symptoms of heat exhaustion that do not improve after cooling
• Vomiting or unable to keep fluids down
• Dizziness, weakness, or fainting
• Confusion or unusual behavior — call emergency services
• A baby, young child, or older adult with heat symptoms

Book a routine appointment if:

• You have had heat illness before and want advice on preventing it
• You take medicines and want to know if they raise your heat risk
• You have a long-term health condition and need a hot-weather plan
• You feel anxious or unwell after a heat illness

Diagnosis

A healthcare provider will ask about heat exposure, symptoms, fluids, medicines, and health conditions. They will check temperature, pulse, blood pressure, breathing, and mental state. Heatstroke is usually recognized quickly from the signs and the situation.

Tests that may be done

• Temperature check
• Blood pressure and pulse check
• Breathing and oxygen check
• Blood tests to look for dehydration and organ strain
• Urine tests to check hydration and kidney function
• Heart tracing if needed

What to expect at your appointment

For heat exhaustion, the focus is on cooling and checking that you are safe. For heatstroke, you may be treated in an emergency department or hospital so your body can be cooled and your vital organs monitored.

Treatment

Heat exhaustion is treated by cooling the body and replacing fluids. Heatstroke is a medical emergency and needs fast cooling and hospital care. Do not try to treat heatstroke at home.

Self-care at home

• Move to a cool, shaded, or air-conditioned place
• Lie down and loosen or remove extra clothing
• Cool the skin with cool water, wet cloths, a fan, or a cool shower if the person is fully alert
• Sip water or a mild oral rehydration drink if the person is awake and not vomiting
• Rest and avoid more heat for the rest of the day
• Check on the person often
• Do not give drinks to someone who is confused, drowsy, or unconscious

Medical treatments

In hospital, care teams cool the body quickly using methods such as cool water, ice packs, fans, and cool fluids given through a vein. They monitor breathing, heart rate, blood pressure, and organ function. Treatment is supportive and aimed at bringing the body temperature down safely. Specific medicines are chosen by the care team when needed, but they are not the main treatment for heat illness.

When is surgery considered?

Surgery is not used to treat heat exhaustion or heatstroke. Care focuses on cooling the body and supporting vital organs.

Living with this condition

After a heat illness, take it easy for a few days. Avoid hot places and heavy exercise until you feel fully well. Check the weather and plan outdoor tasks for cooler times of day.

Lifestyle tips

• Drink fluids regularly, even before you feel thirsty
• Wear light, loose clothing
• Use shade, fans, air conditioning, or cool rooms
• Take breaks during work or exercise in heat
• Avoid heavy alcohol in hot weather
• Check on friends, family, and neighbors who are at higher risk

Diet and exercise

Eat regular meals and drink water before, during, and after exercise. If you sweat a lot for a long time, a sports drink or oral rehydration solution can help replace salts, but water is usually enough for everyday activity. Build up slowly if you are new to heat or exercise.

Mental health and emotional wellbeing

It is normal to feel worried or shaken after a heat illness. Heat can also make people feel irritable, anxious, or low. If these feelings continue or affect your daily life, talk to a healthcare provider or a trusted support service.

Prevention

Yes, most heat illness can be prevented. The key is to stay cool, drink enough, and avoid overdoing it in heat.

Vaccines

There is no vaccine for heat exhaustion or heatstroke.

Screening programmes

There is no routine screening test. During hot weather, check on people at higher risk, such as older adults, babies, and people who live alone.

Complications

If left untreated

• Heat exhaustion can worsen to heatstroke
• Heatstroke can damage the brain, heart, kidneys, and other organs
• Heatstroke can cause seizures, coma, or death if not treated quickly
• Some people have lasting tiredness or sensitivity to heat after a severe heat illness

Long-term outlook

Most people with heat exhaustion recover well with prompt cooling and fluids. People with heatstroke need emergency care, and many recover, especially when cooling starts quickly. Taking prevention steps seriously makes a big difference.

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