What is the difference between heat exhaustion and heat stroke?

Being in the hot summer sun can be fun, but it can also be risky if you are not cautious. Heat-related illnesses include heat exhaustion and heat stroke, which occur when the body cannot control its temperature in extreme heat. Heat stroke is particularly dangerous—it’s a medical emergency that requires prompt action. Below, we explain the differences, causes, risks, and prevention strategies for these two conditions.

Heat exhaustion vs. heat stroke: What’s the difference? 

• Heat exhaustion: A state in which the body’s temperature is elevated but not to the point of irreversible harm. The body is trying to cool down, and you are overheating and exhausted.
• Heat stroke: A serious condition in which the body’s temperature regulation fails, and internal temperature rises to dangerous levels. It can damage organs or even kill if not treated quickly.

Symptoms of heat exhaustion

• Heavy sweating
• Clammy, sweaty skin despite the heat
• Dizziness or fainting
• Nausea or vomiting
• Fatigue or weakness
• Muscle cramps
• Rapid, weak pulse
• Headache

These symptoms are a sign that you need to cool down before your condition worsens.

Symptoms of heat stroke

Heat stroke features more severe symptoms, including:

• Elevated body temperature (104°F or higher)
• Skin that is hot and dry or occasionally sweating profusely
• Changes in mental status (confusion, agitation, or unconsciousness)
• Rapid, strong pulse
• Seizures
• Nausea and vomiting
• Shallow breathing

These are signs of a medical emergency—do not delay getting professional help. Also read: Heat related illness: Prevention and tips

Causes of heat exhaustion

Heat exhaustion usually occurs when a person spends too long in high heat without adequate hydration. Contributing factors include:

• Difficult physical work in high temperatures
• Inadequate water intake
• Wearing heavy or tight clothing that traps heat
• Excessive humidity, which diminishes the body’s ability to sweat and cool off

Causes of heat stroke

Heat stroke may result from untreated heat exhaustion or from:

• Extremely hot weather (such as during heat waves)
• Prolonged sweating in high heat
• Certain medications (e.g., diuretics, antihistamines) that affect heat regulation
• Alcohol consumption, which dehydrates the body
• Chronic health conditions (e.g., heart disease, obesity) that impair heat regulation

Risks of heat exhaustion

While less deadly than heat stroke, heat exhaustion can lead to complications without treatment:

• Dehydration, which can exacerbate other heat-related illnesses
• Heat stroke if body temperature is not lowered promptly

Risks of heat stroke

Heat stroke is far more serious and can cause:

• Damage to organs, particularly the brain, heart, and kidneys
• Convulsions or loss of consciousness
• Death, if untreated

Heat stroke poses higher risks for children, the elderly, and those with chronic health problems.

Preventing heat exhaustion

• Hydrate: Sip water even when you’re not thirsty.
• Wear light, loose, and light-coloured clothing to stay cool.
• Take breaks: Move to the shade or an air-conditioned space during outdoor activities.
• Avoid the hottest hours: Usually between 11 a.m. and 3 p.m.
• Use fans or air conditioning to reduce heat exposure.

Preventing heat stroke

• Heed heat advisories: Avoid exertion during hot weather.
• Cool off promptly: Use water or air conditioning if symptoms appear.
• Acclimate gradually: Avoid sudden intense activities in hot climates.
• Use sunscreen: Sunburn disrupts sweating, making it harder to cool down.

Also read: What does a heat rash look like? Signs & home treatment 

Treating heat exhaustion

If you or someone you know has heat exhaustion:

1. Get cooler: Move to the shade, an air-conditioned room, or use a fan.
2. Drink: Choose water or electrolyte drinks; avoid caffeine or alcohol.
3. Cool off: Use cool, damp cloths or take a cool shower.
4. Rest: Avoid physical activity until symptoms improve.

Most cases resolve within an hour with these interventions.

Treating heat stroke

Heat stroke is a medical emergency that requires immediate attention. While waiting for help:

1. Call 000: This condition is life-threatening.
2. Cool the person down: Remove extra clothing and place ice packs on armpits, neck, and groin.
3. Immerse in cool water: If available, this is the fastest way to reduce core temperature.
4. Assess for shock: Monitor breathing and be prepared to perform CPR if necessary.

Heat exhaustion vs. heat stroke

Category	Heat Exhaustion	Heat Stroke
Symptoms	Heavy sweating, clammy skin, dizziness, nausea, fatigue, muscle cramps, rapid weak pulse, headache	High body temperature (104°F+), hot dry skin or profuse sweating, confusion, unconsciousness, strong rapid pulse, seizures, shallow breathing
Causes	Prolonged exposure to heat, dehydration, heavy clothing, high humidity	Untreated heat exhaustion, extreme heat, sweating in high temperatures, medications, alcohol, chronic conditions
Risks	Dehydration, progression to heat stroke	Organ damage (brain, heart, kidneys), seizures, death
Prevention	Stay hydrated, wear light clothing, take breaks, avoid peak heat hours, use cooling methods	Follow heat advisories, cool down quickly, acclimate gradually, use sunscreen
Treatment	Move to a cool area, hydrate, use cool cloths/showers, rest	Remove excess clothing, apply ice packs, immerse in cool water, monitor breathing
When to see a doctor	If symptoms persist over an hour, worsen, or vomiting prevents hydration	Medical emergency – call emergency number (000) immediately
How telehealth can help	Assess symptoms, provide cooling and hydration advice, offer follow-up care	Not for emergencies, but useful for post-recovery guidance

 

When to see a doctor?

• Heat exhaustion: Seek medical help if symptoms last more than an hour, worsen despite cooling efforts, or if vomiting prevents fluid intake.
• Heat stroke: Call 000 immediately. Do not wait for symptoms to improve.

How telehealth can help

Telehealth can assist in managing non-emergency heat-related illnesses:

• Symptom discussion: Providers can help determine if urgent care is needed.
• Personalised advice: Guidance on hydration, cooling methods, and safe medication.
• Follow-ups: Monitor recovery progress remotely.

Telehealth is not a substitute for emergency care in cases of heat stroke but is effective for follow-up and ongoing advice.

Conclusion

Heat-related illnesses are serious but avoidable. Stay hydrated, dress appropriately, and seek shade or air conditioning during extreme heat. Act promptly if symptoms arise, and don’t hesitate to seek medical help when necessary. Stay cool and safe!

24/7 Telehealth appointments with Hola Health

Telehealth provides a fast and convenient way to access medical advice for heat-related illnesses without needing to visit a clinic. With a 24/7 online GP consultation in just 15 minutes, you can:

• Discuss symptoms with an AHPRA-registered online doctor or healthcare practitioner through a secure telehealth appointment.
• Receive expert guidance and instant scripts online for managing heat exhaustion, staying hydrated, and recognising warning signs of heat stroke.
• Get medical certificates online if you need time off work due to heat-related illness.
• Access referrals for blood tests, pathology, or radiology if further evaluation is needed.

Telehealth is ideal for busy professionals, parents, and those in rural areas needing quick access to trusted medical care. If you're experiencing symptoms of heat exhaustion, consult an Australian doctor or medical practitioner anytime, anywhere via telehealth. For heat stroke, seek emergency medical help immediately.