heat stroke

Heat Stroke 101: Symptoms, Causes, First Aid & Treatment

Learn more about heat stroke, including its signs and symptoms, causes, treatment and prevention.

by L.H.

Heat stroke is a dangerous medical emergency that requires immediate attention. Read on to find out more about its symptoms, causes, first aid, and treatment. 

In the  never-ending summer of Singapore’s weather, it’s not an understatement when we say we feel the heat. But what happens when we overheat?

Heatstroke is a dangerously serious medical emergency that requires immediate medical help and attention. When left untreated, heat stroke carries a very real risk of death. In fact, you may have across high profile cases of heat stroke being reported in the media in recent years.

Here at Homage, we’ve prepared a simple and easy to understand guide about everything you need to know about heat stroke. Read on to find out more about its symptoms, causes, and what to do for first aid and treatment. 

What is Heat Stroke?

Heat stroke is a potentially fatal condition that happens when your core body temperature rises above 40 degrees Celsius, resulting in hot dry skin and central nervous system malfunctions, such as delirium, convulsions, or coma.  This typically happens because your body is unable to cool itself down through the usual natural means of sweating.

Heat stroke can be further classified under two categories: exertional or non-exertional heat stroke. 

Exertional heat stroke develops in physically fit  individuals while performing rigorous physical activities. Non-exertional heat stroke, by contrast, can develop during low-level physical activities in elderly, sedentary individuals with other existing medical conditions such as being overweight, diabetes, high blood pressure, heart disease, or alcoholism.

Heat Stroke Symptoms

Given the possible lethality of the condition, it is important that we learn to recognise the signs and symptoms of heat stroke.

Here are the classical symptoms of heat stroke

  • High core body temperature of 40 degrees Celsius and above
  • Hot, red, dry, or damp skin
  • Fast and strong pulse
  • Headache
  • Dizziness 
  • Nausea 
  • Confusion
  • Fainting

If you notice anyone or yourself displaying the above symptoms you must seek immediate medical attention.

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Heat Stroke vs Heat Exhaustion

Heat stroke is often associated with heat exhaustion, a milder form of heat-related illness that can, however, lead to heat stroke if left untreated. While heat stroke happens when your body’s core body temperature rises above 40 degrees Celsius, heat exhaustion can happen when it’s in the range of 38.3 to 40 degrees Celsius.

Heat exhaustion and heat stroke share many symptoms in common. Some symptoms of heat exhaustion include:

  • Rapid heartbeat
  • Fast breathing
  • Heavy sweating
  • Dizziness
  • Fainting
  • Nausea, vomiting, or diarrhea
  • Headache
  • Weakness
  • Muscle cramps
  • Mild, temporary confusion
  • Low blood pressure
  • Dehydration
  • Problems coordinating movement

The main difference between heat exhaustion and heat stroke, however, is that it does not cause significant neurological problems or cognitive impairment, such as delirium, agitation, unconsciousness, or coma. 

Heat Stroke Causes

Heat stroke happens when your body is unable to cool itself down and your core body temperature rises above 40 degree Celsius.

Heat stroke therefore typically results from:

Physically Strenuous Activity

Exertional heat stroke results from an increase in your core body temperature caused by physically demanding    activity under hot environmental conditions. Anyone who exercises or works under such conditions is at risk of getting exertional heatstroke, but it is more likely to happen if your body is not used to high environmental conditions.

Exposure to Hot Environmental Conditions

Non-exertional heat stroke, by contrast, happens after prolonged exposure to  hot, humid weather conditions, where your body is unable to cool itself down through sweating. Older adults and those with chronic illnesses are most at risk.

Since heat stroke primarily results from your body’s inability to cool itself down to normal body temperatures, anything that could hinder your body’s thermoregulation can also lead to heat stroke.

Other possible external causes of heat stroke include:

  • Excessive Clothing

This prevents your sweat from evaporating easily, making it difficult for your body to cool itself down. It also may also trap heat and further increase your core body temperature.

  • Alcohol Consumption

Alcohol affects your body’s thermoregulation, or ability to maintain a constant core body temperature.

  • Dehydration

Not drinking enough water to replenish the fluids lost through sweating can seriously affect your body’s ability to continue cooling itself down, leading to heat stroke.

It is best to pay attention to your own body’s condition and to take appropriate, sensible precautions to avoid getting heat stroke.

Risk Factors for Heat Stroke

It’s possible for heat stroke to affect anyone and everyone. There are, however, some risk factors that make you more vulnerable to heat stroke. 

Such risk factors include:

  • Being in hot and humid environmental conditions
  • Experiencing a heatwave, greater-than-or-equal to three days of temperatures more than 32.2°C
  • Age (older and young patients)
  • Obesity
  • Dehydration
  • Alcohol consumption
  • Drugs including but not limited to: diuretics, anticholinergics, beta- or calcium-channel blockers, antihistamines, amphetamines
  • Existing medical conditions including diabetes mellitus, infections, skin disorders, sickle cell trait, and cardiovascular disease

Potential Complications of Heat Stroke

Depending on how long it’s left untreated heat stroke can lead to serious complications of varying degrees including: 

Organ Damage and Failure

Heat stroke can cause harm to your brain and other vital organs, leading to multiple organ damage and failure.


Without timely adequate medical intervention, heat stroke is a fatal condition.

Heat Stroke Diagnosis

Heat stroke is usually obvious and immediately apparent to observers. 

Your doctor can, however, still order some tests to be done to confirm the diagnosis and to evaluate the extent of harm. 

These tests include:

  • Rectal Temperature Screening

Rectal temperature is the most accurate measurement of your core body temperature and can immediately confirm whether you have heat stroke.

  • Blood Test

This checks your blood sodium and potassium levels to assess if there’s damage to your central nervous system.

  • Urine Test

This evaluates if your kidneys are functioning properly.

  • Muscle Function Tests

This is to check if your muscle tissue has been damaged.

  • X Rays and Imaging Tests

This is to check if your internal organs have been damaged.

Heat Stroke First Aid

If you notice someone having a heat stroke, you must immediately call 995 for the Singapore Civil Defense Force’s Emergency Medical Services to render immediate medical attention to the patient.

You must also take immediate steps to help them cool off and remedy their high core body temperature.

If possible, provide first aid through the following steps:

  • Move the victim to a shaded, cool area and remove outer clothing.
  • Cool the victim quickly with a cold water or ice bath; wet the skin, place cold wet cloths on skin, or soak clothing with cool water.
  • Circulate the air around the victim to speed cooling.
  • Place cold wet cloths or ice on the victim’s head, neck, armpits, and groin; or soak the victim’s clothing with cool water

You must stay with the victim until emergency medical services arrive.

Heat Stroke Treatment

Heat stroke treatment is primarily centered around cooling your core body temperature back down to normal levels, preventing further organ and central nervous system damage. 

In the event of a heat stroke, doctors and medical professionals may take the following steps for treatment:


Where possible, a cold or ice water bath is extremely effective in quickly lowering your core body temperature.

Evaporation Cooling Techniques

When immersion is not immediately feasible, medical professionals may use evaporation cooling techniques to lower your core body temperature. Cold water is misted onto the victim’s body while warm air is fanned over them. As the water evaporates, heat is removed from the body, lowering the victims’ core body temperature.

Cooling Blankets and Ice Packs

The victim may also be wrapped up in a special cooling blanket with ice packs applied to their groin, neck, back, and armpit areas to help speed up the cooling process.

Heat Stroke Prevention

Given the serious consequences of heat stroke, it is imperative that we aim for prevention rather than treatment. 

Here are some preventive steps and tips to make sure that you and your loved ones are protected from heat stroke:

  • Use air conditioning during hot weather
  • Limit your outdoor activities during daytime within reason
  • Wear loose-fitting, light coloured clothing
  • Take note of medication and alcohol consumption that may make you lose fluids, or decrease sweating
  • Be sure to never leave children and other vulnerable persons in a car unattended
  • Stay hydrated at all times, especially during hot weather

When it comes to heat stroke prevention, the most important thing to remember is to always pay attention to our own comfort levels and be aware of any heat-related discomfort that we are experiencing.  

Cease physical activity and rest in cool shaded areas immediately if you feel exhausted or overexerted. Don’t ignore signs of thirst and drink water as and when appropriate.

Often, we are the first line of defense for ourselves in preventing heat stroke.

Homage provides caregiving services for your loved ones at every stage. Our trained care professionals are able to provide companionship, nursing care, night caregiving, home therapy and more, to keep your loved ones active and engaged. 

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  1. Hifumi, T., Kondo, Y., Shimizu, K., & Miyake, Y. (2018). Heat stroke. Journal of intensive care, 6, 30. https://doi.org/10.1186/s40560-018-0298-4
  2. Cdc.gov. 2021. Warning Signs and Symptoms of Heat-Related Illness | Natural Disasters and Severe Weather | CDC. [Webpage]. Retrieved 3 July, from https://www.cdc.gov/disasters/extremeheat/warning.html
  3. 2021. Exercise-Related Heat Exhaustion. [Webpage]. Retrieved 3 July, from https://www.hopkinsmedicine.org/health/conditions-and-diseases/exerciserelated-heat-exhaustion
  4. Leiva, D. and Church, B., 2021. Heat Illness. [Webpage] Retrieved 3 July, from https://www.ncbi.nlm.nih.gov/books/NBK553117/
  5. People’s Liberation Army Professional Committee of Critical Care Medicine (2016). Expert consensus on standardized diagnosis and treatment for heat stroke. Military Medical Research, 3, 1. https://doi.org/10.1186/s40779-015-0056-z
  6. Cdc.gov. 2021. Heat Stress Related Illness | NIOSH | CDC. [Webpage]. Retrieved 3 July, from https://www.cdc.gov/niosh/topics/heatstress/heatrelillness.html
  7. Hifumi, T., Kondo, Y., Shimizu, K., & Miyake, Y. (2018). Heat stroke. Journal of intensive care, 6, 30. https://doi.org/10.1186/s40560-018-0298-4
About the Writer
L.H. is a writer who guzzles coffee a little too much for his own good.
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