Heat stress occurs when our body is unable to cool itself enough to maintain a healthy temperature. Heat-related illness can range from mild conditions such as a rash or cramps to very serious conditions such as heat stroke, which is a condition in which your body becomes dehydrated and overheated, with the body temperature rising above 40.5C.


The body is usually able to dispense heat by radiation of heat through the skin or by evaporation of sweat. The human body generates about 100 watts from internal metabolic processes, but this can escalate to 1,000 watts during heavy exercise. Keeping a constant temperature of around 37°C is vital. To lose heat and maintain core temperature, blood vessels in the skin expand and bring body heat to the skin surface. Perspiration floods out of sweat glands and evaporates from the skin to cool the body.

However, when it's unable to cool itself heat stress can result. It often happens over a fairly short period of time and can be life-threatening if proper medical attention isn't received. Heat-related illnesses can be brought on through being in enclosed, hot places such as rock concerts or sporting events. Strenuous physical activity in a hot environment is also associated with heat-related illnesses as is working in confined areas or any other conditions that raise the body temperature.



It is important to know the signs and symptoms of heat exposure and how you should respond. Symptoms vary according to the type of heat-related illness. Some heat-related illness and common symptoms include:

Deterioration in existing medical conditions – this is the most common health problem of heat stress.

Heat rash (or Prickly Heat) – this is a skin irritation caused by excessive sweating. It looks like a red cluster of pimples or small blisters. It is most likely to occur on the neck and upper chest, in the groin, under the breasts and in the elbow creases.

Heat cramps – these include muscle pains or spasms, usually in the abdomen, arms or legs. They may occur after strenuous activity in a hot environment, when the body gets depleted of salt and water. They may also be a symptom of heat exhaustion.

Dizziness and fainting – heat-related dizziness and fainting results from reduced blood flow to the brain. Heat causes an increase in blood flow to the skin and pooling of blood in the legs, which can lead to a sudden drop in blood pressure. There can be a feeling of light-headedness before fainting occurs.

Heat exhaustion – this is a serious condition that can develop into heat stroke. It occurs when excessive sweating in a hot environment reduces the blood volume. Warning signs may include paleness and sweating, rapid heart rate, muscle cramps (usually in the abdomen, arms or legs), headache, nausea and vomiting, dizziness or fainting.

Heat strokethis is a medical emergency and requires urgent attention. Heat stroke occurs when the core body temperature rises above 40.5C and the body’s internal systems start to shut down. Many organs in the body suffer damage and the body temperature must be reduced quickly.


Heat stroke may appear similar to heat exhaustion, but the skin may be dry with no sweating and the person’s mental condition worsens. They may stagger, appear confused, fit, collapse and become unconscious. Warning signs of heat stroke vary but may include:

* Extremely high body temperature
* Rapid pulse
* Difficulty breathing
* Confusion/hallucination
* Hot red and flushed dry skin (no sweat)
* Nausea
* Severe headache
* Dry swollen tongue
* Possible loss of consciousness



Anyone can suffer from heat-related illnesses, but those most at risk are:

* Babies and young children
* People over 65 years, particularly those living alone or without air conditioning
* Athletes
* People who work outside
* Obese individuals
* People who have existing medical conditions, especially heart disease, high blood pressure or lung disease
* Pregnant or breastfeeding women




Suggestion to help prevent heat-related illnesses:

* Drink plenty of water or other cool, non-alcoholic fluids, such as electrolyte replacement solutions (Hydralyte and Gastrolyte). You need to drink more during hot weather, regardless of how active you are. Do not wait until you are thirsty to drink.  

* Stay out of the sun as much as you can and rest often 

* If you must be outdoors, remember to protect yourself from the sun by covering exposed skin with lightweight  clothes and wearing lightweight, using sunscreen, wearing a hat, seek shade and slide on sunglasses.

* Wear light weight clothing, such as bamboo underwear.

* Limit physical activity and if you can, restrict activity to cooler parts of the day.  

* Never leave children or pets in a parked car, even if the windows are left open a fraction.

 * Keep up your energy levels by eating regular, light meals.

 * Check on older, sick or frail people who may need help coping with the heat (at least twice a day).



Treatment options vary according to the type of heat-related illness. Apply first aid and seek medical assistance immediately if you, or someone you are with, shows any sign of heat exhaustion or heat stroke.

Heat rash – Move the person to a cooler, less humid environment, keep the affected area dry and try using unperfumed talcum powder to increase comfort (avoid using ointments or creams as they keep the skin warm and moist and may make the condition worse).


Heat cramps – Stop activity and sit quietly in a cool place, increase fluid intake, rest a few hours before returning to activity and seek medical help if there is no improvement.


Dizziness and fainting – Get the person to a cool area and lay them down. If fully conscious, increase fluid intake.


Heat exhaustion – Get the person to a cool area and lay them down, remove outer clothing, wet skin with cool water or wet cloths, increase fluid intake if they are fully conscious, and seek medical advice.



Heat stroke is an emergency which requires immediate attention. Every minute’s delay in cooling a person with heat stroke increases the likelihood of permanent injury or death. Apply first aid and seek medical assistance immediately if you, or someone you are with, shows any sign of heat exhaustion or heat stroke.

* Call 000 for an ambulance
* While waiting for emergency medical help get the person to a cool shady area and lay them down.
* Remove excess clothing and wet their skin with water or wrap in wet cloths, fanning continuously.
* Do not give the person fluids to drink.
* Position an unconscious person on their side and clear their airway.
* Monitor their body temperature where possible and continue cooling efforts until the body temperature drops below 38°C.
* Wait for the ambulance to urgently transport the person to hospital, where more intensive cooling and support can be given.
* If medical attention is delayed, seek further instructions from ambulance or hospital emergency staff.