Heatstroke: Symptoms and treatment
Heatstroke is the most serious form of
heat-related illness and is a medical emergency. If you suspect that
someone has heatstroke - which some people refer to as sunstroke
.Heatstroke can kill or cause damage to the brain and other internal
organs. Although heatstroke is most common in babies, the elderly and
those with long-term medical conditions, it also takes a toll on healthy
young physically active people such as athletes.
Heatstroke often occurs as a progression from milder heat-related
illnesses such as heat cramps, heat syncope ( fainting) and heat
exhaustion. However, it can strike even if you have no previous signs of
Heatstroke results from prolonged exposure to high temperatures -
usually in combination with dehydration - which leads to failure of the
body's temperature control system. The medical definition of heatstroke
is a core body temperature greater than 41°C, with complications
involving the central nervous system that occur after exposure to high
temperatures. Other common symptoms include nausea, rapid heartbeat,
muscle cramps, seizures, confusion, disorientation, cessation of heavy
sweating and sometimes loss of consciousness or coma.
Risk factors for heatstroke
Heatstroke is most likely to affect older people who live in flats or
homes lacking good airflow and with inadequately shaded south-facing
windows. Other high-risk groups include babies and young children, and
people of any age who don't drink enough water, have chronic diseases,
have mental disabilities or who drink excessive amounts of alcohol.
People who spend a lot of time being physically active in hot weather
are also at greater risk.
The risk of heat-related illness dramatically increases when the heat
index climbs to 26°C or more. So it's important - especially during
heatwaves - to pay attention to the maximum temperature reported in your
local weather forecasts and to remember that it will be hotter in the
sun than in the shade.
If you live in an urban area, you may be especially prone to develop
heatstroke during a prolonged heatwave, particularly if there are
stagnant atmospheric conditions and poor air quality. In what is known
as the "heat island effect," asphalt and concrete store heat during the
day and only gradually release it at night, resulting in higher
Other risk factors associated with heat-related
Age. Infants and children up to age four, and adults over 75 years old,
are particularly vulnerable because they adjust to heat more slowly than
Health conditions. These include heart, lung or kidney disease, being
obese or underweight, having high blood pressure, diabetes, mental
illness, sickle cell trait, alcoholism, sunburn and any conditions that
Medications. These include antihistamines, diet pills, diuretics,
sedatives, tranquillizers, stimulants, seizure medications
(anticonvulsants), heart and blood pressure medications such as
beta-blockers and vasoconstrictors, and medications for psychiatric
illnesses such as antidepressants and antipsychotics. Illegal drugs such
as cocaine and methamphetamine also are associated with increased risk
People with diabetes - who are at increased risk of emergency hospital
visits, hospitalisation and death from heat-related illness - may be
especially likely to underestimate their risk during heat waves.
Consult with your doctor or healthcare provider to see if your health
conditions and medications are likely to affect your ability to cope
with extreme heat and humidity.
When the temperature is high it's best to stay indoors in a cool room.
If you must go outdoors, you can prevent heatstroke by taking these
Wear lightweight, light-coloured, loose-fitting clothing and a
Use a sunscreen with a sun protection factor (SPF) of 30 or more.
Drink extra fluids. To prevent dehydration, it's generally recommended
to drink at least eight glasses of water, fruit juice or vegetable juice
per day. Because heat-related illness also can result from salt
depletion, it may be advisable to substitute an electrolyte-rich sports
drink for water during periods of extreme heat and humidity.
Take additional precautions when exercising or working outdoors. The
general recommendation is to drink 750ml (1.25 pints) of fluid two hours
before exercise and consider adding another 225ml (8floz) of water or
sports drink right before exercise. During exercise, you should consume
another 225ml (8floz) of water every 20 minutes, even if you don't feel
Reschedule or cancel outdoor activity. If possible, shift your time
outdoors to the coolest times of the day, either early morning or after
Other strategies for preventing heatstroke
Monitoring the colour of your urine. Darker urine is a sign of
dehydration. Make sure you drink enough fluids to maintain very light-coloured
Measuring your weight before and after physical activity. Monitoring
lost water weight can help you determine how much fluid you need to
Avoid fluids containing caffeine or alcohol. Both substances can make
you lose fluids and worsen heat-related illness. Also, do not take salt
tablets unless your doctor has told you to do so. The easiest and safest
way to replace salt and other electrolytes during heat waves is to drink
sports drinks or fruit juice.
Check with your doctor before increasing liquid intake if you have
epilepsy or heart, kidney or liver disease, are on fluid-restricted
diets, or have a problem with fluid retention.
If you live in a flat or house without fans, try to spend at least two
hours each day - preferably during the hottest part of the day - in an
air-conditioned environment. Avoid rooms with south-facing windows,
which get the most sunlight. At home, draw your curtains or blinds
during the hottest part of the day. If you can, open windows at night on
two sides of your building to create cross-ventilation.
Symptoms of heatstroke
The hallmark symptom of heatstroke is a core body temperature above
41°C. But fainting may be the first sign.
Other symptoms may include:
Dizziness and light-headedness
Lack of sweating despite the heat
Red, hot and dry skin
Muscle weakness or cramps
Nausea and vomiting
Rapid heartbeat, which may be either strong or weak
Rapid, shallow breathing
Behavioural changes such as confusion, disorientation or staggering
First aid for heatstroke
If you suspect that someone has a heatstroke, call 999 immediately or
bring the person to a hospital. Any delay in seeking medical help can be
While waiting for the paramedics to arrive, initiate first aid. Move the
person to an air-conditioned environment - or at least a cool, shady
area - and remove any unnecessary clothing.
If possible, take the person's core body temperature and initiate first
aid to cool it to below 40°C. If no thermometers are available, don't
hesitate to initiate first aid.
You may also try these cooling strategies:
Fan air over the patient while wetting his or her skin with water from a
sponge or garden hose.
Apply ice packs to the patient's armpits, groin, neck and back. Because
these areas are rich with blood vessels close to the skin, cooling them
may reduce body temperature.
Immerse the patient in a shower or tub of cool water, or an ice bath.
If emergency response is delayed, call the hospital Accident & Emergency
department for additional instructions.
After you've recovered from heatstroke, you'll probably be more
sensitive to high temperatures during the following week. It's best to
avoid hot weather and heavy exercise until your doctor tells you that
it's safe to resume your normal activities.