Heat exhaustion occurs when the body cannot lose heat fast enough. If not treated quickly, it can lead to heatstroke which is a much more dangerous condition.

The signs of heat exhaustion include:

• feeling faint,
• dizziness,
• rapid heartbeat,
• nausea,
• headache,
• low blood pressure,
• tiredness,
• confusion,
• loss of appetite, and
• general discomfort

Sometimes, heat exhaustion can also result in visual hallucinations and vomiting. The symptoms can often occur suddenly after excessive sweating and not drinking enough.

If you or someone else has the signs of heat exhaustion, take the following actions:

• move out of the sun to a cool, shady spot or air-conditioned room,
• lay the person down on their back and elevate their feet slightly,
• loosen or remove clothing,
• get the person to drink cold water (not iced) to replace lost fluids, and
• monitor the person closely and if they show signs of confusion or fainting, or if they have a fever, call 911 to get medical assistance.

Heat exhaustion can lead to heatstroke. Heatstroke occurs when the body's normal cooling system ceases to function. If left untreated, a person with heatstroke can slip into a coma and die.

The signs of heatstroke include:

• an elevated temperature,
• hot, dry skin (not sweaty),
• rapid heartbeat,
• increased or lowered blood pressure,
• confusion and restlessness,
• headache, and
• unconsciousness.

Anyone can get heatstroke but the elderly are particularly at risk. Fainting is often the first sign of heatstroke in older people. Other groups who are at risk are those who are obese, people with lupus and those born with an impaired ability to sweat.

If you suspect heatstroke, you should:

• move out of the sun to a cool, shady spot or air-conditioned room,
• cool the person by covering them with damp sheets or spraying them with water,
• cool the person using a fan, and
• call 911 or take the person to the hospital immediately where their core body temperature will be lowered to a safe level.

The seriousness of heatstroke should not be underestimated. You can die from the condition as a result of heart failure, kidney failure or brain damage caused by excess body heat. It's therefore crucial that medical assistance is sought immediately.