Heat stress warning signs and how it impacts your body

Hot weather can cause serious health problems. Learn who is most at risk of heat stress, how to recognise it, and how to avoid overheating.

Australia’s hot weather can affect any one of us and put us at greater risk of heat stress.

In a country known for its extreme events, including bushfires, floods, storms and cyclones, heatwaves are our most dangerous environmental hazard, resulting in more deaths than all those other hazards combined.

So what is heat stress? When is it most likely to occur?

And can something as simple as drinking enough water help you avoid falling victim to it?

What is heat stress?

Heat stress happens when your body’s ability to regulate its internal temperature starts to falter because it can’t get rid of excess heat through sweating.

Hot and humid environments cause sweating to become less efficient.

Mild heat stress can result in minor conditions including heat cramps and heat rash.

But it can also lead to more serious health problems such as heat exhaustion, which is caused by an excessive loss of water and salt through heavy sweating.

And then there’s heat stroke, the most dangerous heat-related illness.

This is where the body’s ability to cool itself down fails completely, causing your internal temperature to rise rapidly to dangerous levels.

Heat stress is more likely to occur during extreme heat conditions, including heatwaves.

What are the signs of heat stress?

Different heat-related illnesses have different signs and symptoms.

Early signs

Early signs of dehydration and heat stress include heavy sweating, feeling faint or dizzy, being thirsty, and feeling lethargic.

Heat exhaustion

It’s important to know what heat exhaustion looks like as this can develop into heat stroke if it’s not addressed.

Signs and symptoms include:

  • headache
  • nausea or vomiting
  • pale skin
  • weakness
  • irritability
  • heavy sweating
  • thirst
  • weak, rapid pulse
  • muscle cramps.

First-aid for heat exhaustion includes moving out of the heat, drinking water and trying to cool down by using ice packs or damp towels, or by taking a cool shower.

If symptoms don’t improve, see a doctor.

Heat stroke

Heat stroke is a medical emergency, so it’s crucial to know the symptoms, which include:

  • headache
  • nausea
  • slurred speech
  • profuse sweating or very hot, dry skin
  • extreme thirst
  • agitation and altered mental state
  • muscle twitching or seizures
  • rapid breathing
  • very high body temperature
  • loss of consciousness.

Left untreated, heat stroke can cause permanent disability or death, so immediate medical attention is required.

Who is at risk of heat stress?

While it can affect anyone, some people are at greater risk, including older people, babies and young kids, pregnant women, people with existing medical conditions, and those who are homeless.

A new safety campaign by Sweltering Cities is designed to shine a light on the impacts of heatwaves.

“When it comes to heatwave advice, we’re told to stay out of the sun, drink water and check in on people,” Sweltering Cities executive director Emma Bacon says.

But who should we be checking in on, when should we do it, and what advice can we give?

“This campaign is all about making supporting others as easy as possible.”

The Heatwave Check-In program provides a variety of online resources to help grow understanding of heatwaves and heat stress, including who might be most at risk.

“It’s time to call Nan, text your friend who lives in a hot home, or drop in on family who might be struggling to keep little kids cool on hot days,” Emma says.

How to avoid heat stress

The following tips can help you avoid heat-related illness during hot weather:

  • Stay across weather forecasts, including the Bureau of Meteorology’s Heatwave Service for Australia.
  • Drink plenty of water, even if you aren’t thirsty.
  • Keep your house cool by closing curtains and blinds and using awnings during the day, using the oven as little as possible and, if you don’t have air conditioning, using fans and opening windows at night.
  • Keep your body cool by staying out of the sun, avoiding the outdoors between 11am and 5pm, wearing light and loose-fitting clothing, taking cool showers, and avoiding strenuous physical activity.

If you have a baby, it’s worth knowing that a common strategy used to protect against heat stress when out and about can have the opposite effect, with a University of Sydney study showing that covering a pram with a dry muslin wrap increases the pram’s temperature by almost 4°C.

In contrast, draping a damp muslin cloth and using a clip-on fan reduces the pram’s temperature by 4.7°C relative to the temperature outside.

“Four degrees can make a really substantial difference, both to the thermal comfort and reducing the risk of overheating during hot weather,” senior study researcher Dr James Smallcombe says.

The research also recommends re-wetting the muslin cloth every 20 minutes and regularly monitoring your baby for signs of heat stress.

More on living well in the heat:

Written by Karen Fittall.