Heat exhaustion vs heatstroke – both are heat-related illnesses, but heatstroke is a life-threatening medical emergency. Heat exhaustion commonly causes heavy sweating, weakness, dizziness, headache, nausea and thirst. Heatstroke is much more serious and can cause confusion, altered behaviour, slurred speech, seizures or loss of consciousness. If you suspect heatstroke, call Triple Zero (000) for an ambulance and start cooling the person immediately. (NSW Health)
Sydney’s hot weather can put people at risk in many settings. It might be a construction worker doing physical work in direct sun, a child playing school sport, someone exercising outdoors or a family spending a long summer day at the beach. The important thing is knowing when someone is struggling with the heat — and recognising when their condition may have become an emergency.
Key Takeaways
- Heat exhaustion and heatstroke are not the same: heatstroke is a life-threatening emergency.
- Confusion, altered behaviour, seizures or unconsciousness are serious warning signs of possible heatstroke.
- Call 000 immediately for suspected heatstroke and start cooling the person while help is coming.
- A person with heatstroke may still be sweating, so don’t rely on dry skin as the deciding sign.
- First aid training provides practical skills for responding if a heat-affected person deteriorates or becomes unresponsive.
What Is the Difference Between Heat Exhaustion vs Heatstroke?
The simplest distinction is severity.
Heat exhaustion is the body’s response to losing water and salt in hot conditions, commonly through excessive sweating or strenuous physical activity. The person may feel very unwell, but prompt recognition, rest and cooling can help prevent the situation from becoming more serious. NSW Health lists symptoms including heavy sweating, headache, dizziness, nausea or vomiting, muscle cramps, weakness, thirst and a rapid pulse.
Heatstroke, on the other hand, is the most severe form of heat-related illness. The body’s ability to control its temperature is overwhelmed, and the condition can rapidly become life-threatening. Healthdirect identifies changed behaviour, confusion, poor coordination, slurred speech, seizures and loss of consciousness among the warning signs. (Healthdirect)
That difference matters because a person who initially looks exhausted from the heat may deteriorate.
Heat exhaustion should therefore never simply be dismissed as someone being “a bit hot”. Stay with the person, cool them and keep watching their condition.
Heat Exhaustion Treatment: What Should You Do?
If someone appears to have heat exhaustion, get them out of the heat and into a cooler indoor area or shade. Stop strenuous activity and encourage them to rest.
Remove or loosen unnecessary, tight or heavy clothing and begin cooling them. Depending on what is available, this might involve air conditioning, a fan, cool water, a cool shower or cold packs.
If the person is conscious and able to swallow normally, give them cool fluids. Healthdirect recommends water, an electrolyte sports drink or oral rehydration solution and advises avoiding alcohol and caffeine. The person should stay near somebody who can keep an eye on them until they have recovered.
Pay attention to what happens next.
If the person becomes confused, has a seizure, feels faint, cannot drink or otherwise deteriorates, the situation requires urgent escalation. Healthdirect advises calling 000 for an ambulance in these circumstances.
Heatstroke First Aid: Call 000 and Start Cooling
Suspected heatstroke requires a different level of urgency.
Call Triple Zero (000) immediately and ask for an ambulance.
Don’t wait to see whether the person improves before making the call. Heatstroke can quickly threaten life, and cooling should begin while emergency medical help is on its way. NSW Health, Healthdirect and the Australian and New Zealand Committee on Resuscitation (ANZCOR) all support prompt cooling in heat-related emergencies.
Move the person away from the heat and into shade or a cooler area. Remove or loosen excess clothing and begin cooling them using the best method reasonably available.
Stay with them and continually monitor their condition.
If they are fully conscious and able to swallow safely, small amounts of cool or cold water may be given. ANZCOR specifies that fluids should be given only when the person is fully conscious and able to swallow. (ANZCOR)
If consciousness deteriorates, your priorities change. Continue to assess the person and be prepared to provide basic life support.
How Do You Cool Someone With Heatstroke?
You don’t need sophisticated medical equipment to begin cooling someone.
NSW Health recommends starting to cool the person in any way available. Options include spraying them with cool water, using a cool damp sponge or cloth, wetting their skin and clothing, or using a cool shower or bath where appropriate. It also recommends wrapped ice or cold packs applied to areas such as the neck, groin and armpits.
Healthdirect similarly advises removing excess clothing and using cool water, wet towels or clothing and fanning damp skin. (Healthdirect)
The central principle is straightforward: call for emergency help and start cooling rather than waiting passively for the ambulance.
ANZCOR recommends that first aiders send for an ambulance early in heat-induced illness and cool the person by the best means available while waiting for more advanced care.
At the same time, don’t become so focused on cooling that you stop watching the casualty. Their responsiveness and breathing remain critical.
What If the Person Becomes Unconscious?
A heat-related emergency can deteriorate quickly.
If the person becomes unresponsive, follow the DRSABCD action plan and check whether they are breathing normally. An unconscious person who is breathing normally should be appropriately positioned and monitored. If they are unresponsive and not breathing normally, commence CPR and use an AED as soon as one is available.
Healthdirect specifically advises that an unconscious person with heatstroke may need CPR.
This is one reason practical first aid knowledge matters. Reading about heatstroke can teach you the warning signs, but an emergency becomes considerably more demanding when the person in front of you suddenly stops responding.
Recognised training with First Aid Course Sydney by FirstAidPro gives participants the opportunity to practise emergency assessment, CPR, AED use and other first aid responses before those skills are needed in a real incident.
Who Is Most at Risk During Sydney's Hot Weather?
Heat-related illness can affect anyone, but risk increases in particular circumstances.
Sydney’s outdoor workers are an obvious example. Construction work can combine direct sun, strenuous physical activity, radiant heat, heavy equipment and protective clothing. SafeWork NSW also identifies gardeners, landscapers, agricultural workers, emergency workers and people working in hot indoor environments among occupations where heat exposure may be significant. (SafeWork NSW)
The same principles extend beyond work.
Strenuous sport or exercise on a hot day can generate considerable internal heat. Children participating in outdoor activities, people spending hours at the beach and anyone undertaking prolonged physical activity in Sydney’s summer conditions need to be watched for signs of heat-related illness.
Individual vulnerability varies too. Pregnancy, age, physical fitness, certain health conditions, medications, alcohol and lack of acclimatisation can affect a person’s ability to cope with heat.
Heat Risk Isn't Just About the Temperature
A 35°C day doesn’t affect every person or every environment in exactly the same way.
SafeWork NSW emphasises that heat exposure depends on more than air temperature. Humidity, airflow, radiant heat from the sun or surrounding surfaces, clothing and PPE, the intensity of physical work and individual factors all influence risk.
High humidity is particularly relevant because it reduces the effectiveness of sweating as a cooling mechanism.
This is also why there isn’t a single NSW workplace temperature at which all work automatically has to stop. SafeWork NSW states that the WHS Regulation does not specify one precise stop-work temperature because the risk of heat-related illness depends on multiple factors.
For a construction crew working physically demanding jobs in direct sun, for example, simply checking the temperature on a phone doesn’t provide a complete assessment of heat risk.
Preventing Heat Exhaustion Before It Becomes an Emergency
Prevention starts before someone feels sick.
Staying appropriately hydrated, planning strenuous activities around hot conditions, using cooler or shaded areas for rest and taking sensible breaks can all reduce heat exposure. People should also look out for each other because someone developing heat illness may not immediately recognise how impaired they have become.
For Sydney workplaces, heat should be managed as a work health and safety hazard rather than leaving individual workers to cope with it themselves.
SafeWork NSW recommends the standard risk-management approach: identify the hazard, assess the risks, control those risks and review the controls. Measures may include changing when or where work is performed, managing workloads, improving airflow or cooling, worker rotation and providing suitable rest arrangements.
Training workers to recognise heat illness is also important. A colleague who suddenly becomes clumsy, confused or unusually irritable on a hot worksite shouldn’t simply be told to “push through”.
Why First Aid Training Matters in Hot Weather
Heat exhaustion and heatstroke demonstrate why good first aid is about more than memorising symptoms. You need to recognise when a situation is becoming serious, know when to call 000, begin appropriate first aid and respond if the casualty’s condition suddenly deteriorates.
Those decisions become easier when you’ve practised them.
Completing a recognised First Aid course in Sydney with First Aid Course Sydney by FirstAidPro can build practical skills for responding to emergencies at work, at home and in the community. Training covers essential first aid responses, including casualty assessment, CPR and AED use, so you’re better prepared when someone needs immediate help.
Sydney’s hot weather is part of life. Heatstroke doesn’t have to be treated as an inevitable consequence of it.
Remember the crucial distinction: heat exhaustion requires prompt attention and cooling; suspected heatstroke requires an immediate call to 000, active cooling and continued first aid until professional help takes over.
Related Reading
- NSW Health — Heat-related illness: signs, symptoms and first aid
- Healthdirect Australia — Heatstroke
- ANZCOR — Guideline 9.3.4: Heat Induced Illness (Hyperthermia)
- SafeWork NSW — Working in Extreme Heat
- SafeWork NSW — Managing Extreme Heat at Your Workplace
FAQs
What is the main difference between heat exhaustion and heatstroke?
Heat exhaustion commonly causes symptoms such as heavy sweating, weakness, dizziness, headache, nausea, thirst and muscle cramps. Heatstroke is much more severe and may involve a very high body temperature and neurological changes such as confusion, poor coordination, slurred speech, seizures or loss of consciousness. Heatstroke is a life-threatening emergency requiring an immediate 000 call.
What are the first signs of heatstroke?
Signs can include a rapid rise in body temperature, intense thirst, rapid breathing and pulse, nausea or vomiting and changes in behaviour or coordination. Confusion, slurred speech, seizures and loss of consciousness are particularly concerning signs. A person with heatstroke can be sweaty or have hot, dry skin.
Should you give water to someone with heatstroke?
If the person is fully conscious and can swallow safely, ANZCOR recommends giving cool or cold water to drink. Do not attempt to give fluids to someone who is unconscious or cannot swallow safely.
How do you cool someone with heatstroke?
Call 000 first, move the person somewhere cooler and remove or loosen excess clothing. Start cooling using whatever suitable means are available, such as cool-water spraying or sponging, wetting the skin and clothing, fanning damp skin, a cool shower or bath where appropriate, or cold packs. Continue monitoring the person while waiting for the ambulance.
Can heat exhaustion turn into heatstroke?
Yes. Healthdirect advises that heat exhaustion can develop into heatstroke. Someone with heat exhaustion should therefore be moved somewhere cool, rested, cooled, given suitable fluids when they can drink safely and monitored for deterioration. If signs of heatstroke develop, call 000 immediately.
