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Heat-Related Illnesses

Know the Symptoms of Heat-Related Illnesses

!Heat Cramps


  • Heavy sweating
  • Painful muscle cramps or spasms


  • Stop activity for a few hours
  • Move to a cooler location
  • Drink water, clear juice, or a sports beverage
  • Gently stretch and massage affected areas.
  • Seek medical attention if cramps do not subside within one hour

!! Fainting (Heat Syncope)


  • Fainting
  • Dizziness


  • Move to a cool, shady area
  • Drink water, clear juice, or a sports beverage

!!! Heat Exhaustion


  • Heavy sweating
  • Weakness
  • Fatigue
  • Headache
  • Dizziness
  • Nausea or vomiting
  • Fainting
  • Irritability
  • Thirst
  • Decreased urine output


  • Move to an air-conditioned environment
  • Lie down
  • Loosen clothing or change into lightweight clothing
  • Sip cool, non-alcoholic beverages
  • Take a cool shower or bath, or apply cool, wet cloths to as much of the body as possible
  • Seek medical attention if symptoms worsen or last longer than one hour, or if the victim has heart problems or high blood pressure

!!!! Heat Stroke


  • Very high body temperature
  • Altered mental state
  • Throbbing headache
  • Confusion
  • Nausea
  • Dizziness
  • Hot, dry skin or profuse sweating
  • Unconsciousness


  • Call 911 immediately and follow the operator’s directions — THIS IS A MEDICAL EMERGENCY!
  • Reduce the person’s body temperature using cooling methods such as wrapping the person in cool clothes, applying ice packs to their neck or armpits, or fanning them
  • After administering cooling methods, move the person to a cooler place
  • Do NOT give liquids to a person who is unconscious from a heat stroke
  • If there is vomiting, turn the victim on his or her side to keep the airway open

Extreme heat events in Canada are already occurring and are expected to become more common, more severe, and longer-lasting as our climate changes.

What is an extreme heat event?

Four environmental factors work together to make it hot enough to put health at risk.

  • High temperature
  • High relative humidity (moisture in the air)
  • Radiant heat (from the sun)
  • Wind speed (lack of air movement)

Heat affects everybody.

A normal body temperature for adults is around 37°C or 98.6°F. When you are sick, you may get a fever with symptoms such as headache, sweating, or fatigue.

Much like a fever, extreme heat stresses your body’s ability to maintain its normal temperature and can result in similar symptoms.

Very high body temperatures may damage the brain and other vital organs. Heat illnesses are preventable and knowing the risks and how to protect yourself will keep you safe over the summer.

Who is most at risk?

  • Infants and young children
  • Pregnant women
  • Older adults
  • Those with certain health conditions including heart diseases and mental illness.
  • People who are under the influence of drugs or alcohol
  • Those who work outside
  • People who are homeless and low-income earners
  • People who have mobility constraints or who are bedridden

What Should I Do During An Extreme Heat Event?


  • Visit those at high risk for heat illnesses during extreme heat events. Frequently visit neighbours, friends and older family members, especially those who are chronically ill, to make sure that they are cool and hydrated.
  • Use air conditioners or spend time in air-conditioned places, such as malls, or libraries. Even a few hours spent in air-conditioning can help your body stay cooler when you go back to the heat.
  • Use an electric fan to provide comfort when the temperature is below 35°C (95°F). Fans can help sweat evaporate from your body, which helps cool it down. They are less effective against heat related illness when the temperature is higher.
  • Keep your house cooler by keeping the curtains or blinds closed and keeping the lights off.
  • Stay hydrated by drinking water or beverages without caffeine, sugar, or alcohol throughout the day, especially before you feel thirsty. Increase your fluid intake, regardless of your activity level.
  • Take a cool shower or bath to help cool off.
  • Minimize direct exposure to the sun. If you must go out, wear a wide-brimmed hat and sunglasses.
  • Put on sunscreen of SPF 15 or higher 20 minutes before going outside. Most effective are labelled as “broad spectrum” or “UVA/UVB”. Reapply according to package instructions.
  • Wear loose-fitting, light-coloured clothing.
  • Know the symptoms of heat-related illness and the appropriate responses.
  • Check the local news for health and safety updates regarding the weather. Plan or reschedule outdoor activities during cooler parts of the day.


  • Leave children, pets or persons with mobility problems alone in cars for any amount of time.
  • Drink alcohol to stay cool. Alcoholic drinks may lead to dehydration.
  • Use the stove or oven to cook. It will make your house hotter.
  • Wear heavy, dark clothing. Dark colours absorb heat from the sun.
  • Exercise outdoors during the hottest hours of the day (usually 10 a.m. to 5 p.m.). If you must be outdoors, try to rest often in shady areas, indoors, or use a sun umbrella.

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