Heat Exhaustion vs Heatstroke: Signs, First Aid and When to Get Help

Every Australian summer, people get this wrong in the same direction. Someone goes quiet at a barbecue, or stops making sense halfway through a run, and everyone assumes they need a drink and a sit down. Heat exhaustion usually does respond to that. Heatstroke does not, and the gap between the two can be twenty minutes. If someone has overheated and is not bouncing back, an after-hours GP consultation or a telehealth appointment can help you work out the next step - but if they are confused, skip all of that and call 000.

The one difference that actually matters

The line between heat exhaustion and heatstroke is the brain.

In heat exhaustion the person feels dreadful but is still themselves. They know where they are and answer you properly. In heatstroke the body has stopped controlling its temperature and the brain starts to suffer - they become confused, irritable, vague, or stop making sense. That change is the warning, and the only one worth relying on.

One myth is worth killing here. Plenty of people were taught that heatstroke means hot dry skin and no sweating. That holds for the kind that creeps up on an elderly person indoors during a heatwave. But when it comes on through exertion - a tradesperson on a roof, a teenager at cricket - they are often still drenched in sweat. Sweaty skin does not rule it out. If they are not thinking straight, treat it as heatstroke.

Heat exhaustion: what it looks like

Heat exhaustion is the body struggling but still coping. Better Health Channel lists the usual signs:

• Heavy sweating, with pale skin
• Weakness, faintness or dizziness
• Headache, nausea or vomiting
• Muscle cramps
• Intense thirst, and passing less urine than usual
• Irritability

The person is miserable but lucid. Treated properly, most improve within half an hour.

Heatstroke: what it looks like

Heatstroke is a different condition, not a worse version of the same one. Core temperature climbs past the point the body can manage, and organs start to be affected.

Alongside the brain signs above, you may see rapid breathing, a dry tongue, muscle twitching and skin that is red and hot. The person may have had heat exhaustion symptoms shortly before, or seemed fine and then deteriorated fast.

Untreated heatstroke damages the brain, kidneys, liver and heart, and can be fatal. Not a wait-and-see situation.

First aid for heat exhaustion

Move them somewhere cool and shaded, or into air conditioning. Lie them down, legs slightly raised. Loosen or remove excess clothing. Cool them with a damp cloth, a cool water spray, or an ice pack wrapped in a damp towel against the neck, armpits or groin, and fan them. Give frequent sips of cool water, provided they are not vomiting. St John Ambulance sets out the same sequence in its first aid guidance for heat-induced illness.

If they are not noticeably better within thirty minutes, or start vomiting and cannot keep fluids down, get medical advice - a bulk billed telehealth appointment is a reasonable way to do that after hours. If their mental state changes at any point, stop and call 000.

First aid for heatstroke

Call 000 first, then cool them while you wait. Get them into shade or air conditioning, lie them down, loosen clothing, and cool aggressively - wet the skin, fan them, wrapped ice packs on the neck, armpits and groin. A cool shower works if they are alert enough to manage it safely.

Two things not to do. Do not give fluids to anyone confused, drowsy or semi-conscious, because they can choke - water only if they are fully awake and swallowing normally. And do not leave them alone. If they lose consciousness, roll them onto their left side in the recovery position, check breathing, and start CPR if they stop breathing.

Who is most at risk

Adults over 65, babies and young children, and pregnant women all handle heat less well. So do people with chronic conditions, people on certain medications, and anyone without a practical way to keep cool at home.

Then the group nobody expects: fit, healthy people exerting themselves. Outdoor workers and athletes make up a large share of cases, precisely because they push on. Children overheat faster than adults, and the Sydney Children's Hospitals Network factsheet on heat illness in children is worth reading before summer if you have young kids.

Never leave a child or pet in a parked car, not even briefly with the windows down. The inside can reach double the outside temperature within minutes.

Staying ahead of it

Drink through the day rather than waiting until you are thirsty - thirst lags behind what the body already needs. Go easy on alcohol. Shift physical work to early morning or evening. Wear loose, light clothing. Find somewhere cool if home gets unbearable; a library counts. And check on older neighbours during a heatwave, because the people most at risk are the least likely to ask.

Where 13CURE fits

Heatstroke needs an ambulance. Heat exhaustion that is settling needs rest, cool and fluids. The middle ground - heat exhaustion dragging on, someone elderly after a rough afternoon, a child who seems off after a hot day - is where an after-hours doctor earns their keep. Bookings run Monday to Friday 6pm to 8am, Saturdays from 12pm, and 24 hours Sundays and public holidays. Consultations are bulk billed for eligible Medicare and DVA cardholders - the bulk billing GP page covers eligibility, and a home doctor visit may be available depending on location, listed on the areas we cover page.