Temperature Extremes

If you are visiting a country where the temperature exceeds what you are used to at home, take extra precautions to guard against heat or cold-related illnesses.

Heat-related illnesses, in order of decreasing severity, include heat stroke, heat exhaustion, heat cramps and heat rash.

Heat stroke

Heat stroke occurs when the body is no longer able to control its temperature in extreme heat: the body temperature rises rapidly, the sweating mechanism fails, and the body is unable to cool down. Heat stroke can cause death or permanent disability if emergency treatment is not given.

Warning signs of heat stroke vary but may include:

  • an extremely high body temperature (above 39.4 °C, orally);

  • red, hot, and dry skin, because of no sweating;

  • rapid, strong pulse;

  • throbbing headache;

  • dizziness;

  • nausea;

  • confusion, and even unconsciousness.

If you notice your companion to be suffering from any of these signs, call for immediate medical assistance.

Heat exhaustion

Heat exhaustion is the body's response to the excessive loss of water and salt contained in sweat. The victim's temperature is usually normal, and sweating is still intact. If heat exhaustion is untreated, it may progress to heat stroke. Those most prone to heat exhaustion are elderly people, people with high blood pressure and people exercising in a hot environment.

Warning signs of heat exhaustion include:

heavy sweating;

  • paleness;

  • muscle cramps due to low salt level in muscles:

  • pulse fast and weak;

  • breathing fast and shallow;

  • weakness;

  • dizziness;

  • nausea or vomiting.

If you notice any of these signs, adopt cooling measures. Seek medical attention if symptoms worsen or last longer than 1 hour.

Heat cramps

Heat cramps are muscle pains or spasms - usually in the abdomen, arms, or legs - that may occur in people who sweat a lot during strenuous activity. This sweating depletes the body's salt and water. The low salt level in the muscles causes painful cramps. Heat cramps may also be a symptom of heat exhaustion.

If you notice heat cramps, stop all activity and drink cool beverages. Seek medical attention if cramps do not subside in 1 hour.

Heat rash

Heat rash is a skin irritation caused by excessive sweating during hot, humid weather. It can occur at any age but is most common in young children. Heat rash looks like a red cluster of pimples or small blisters. It is more likely to occur on the neck and upper chest, in the groin, under the breasts, and in elbow creases.

On the other side of extreme temperature is coldness. If your plans include outdoor activities in a chilly environment, take extra precautions to protect against cold-related illnesses. Cold-related illnesses include conditions like hypothermia, frostbite and chilblains.


When exposed to extreme cold temperatures, the body begins to lose heat faster than it can be produced. Prolonged exposure to cold will eventually use up your body's stored energy. The result is hypothermia, or abnormally low body temperature. A body temperature that is too low affects the brain, making the victim unable to think clearly or move well. This makes hypothermia particularly dangerous because a person may not know it is happening and will not be able to take preventive measures.

Hypothermia occurs when the body core temperature drops to 35 °C. or lower, often in a very cold environment. It can occur even at cool temperatures if a person becomes chilled from rain, sweat, or submersion in cold water.

Warnings signs of hypothermia:

  • shivering/fumbling hands;

  • exhaustion;

  • confusion/drowsiness;

  • memory loss/slurred speech.


  • bright red, cold skin;

  • very low energy.

If you notice your companion exhibiting any of these signs, take the person's temperature. If it is below 35°C., seek medical attention immediately. Meanwhile, begin warming the person. After the body temperature has increased, keep the person dry and wrapped up in a warm blanket, including the head and neck.

A person with severe hypothermia may be unconscious and may not seem to have a pulse or to be breathing. In this case, handle the victim gently, and seek emergency assistance immediately. Even if the victim appears dead, cardio-pulmonary resuscitation (CPR) should be provided. CPR should continue while the victim is being warmed, until the victim responds or medical aid becomes available. In some cases, hypothermia victims who appeared to be dead could be successfully resuscitated.


Frostbite is an injury to the body that is caused by freezing. Frostbite causes a loss of feeling and color in affected areas. It most often affects the nose, ears, cheeks, chin, fingers, or toes. Frostbite can permanently damage the body, and severe cases can lead to amputation. The risk of frostbite is increased in people with reduced blood circulation and among people who are not dressed properly for extremely cold temperatures.

  • Warning signs of frostbite:

  • a white or grayish-yellow skin area;

  • skin that feels unusually firm or waxy;

  • numbness;

  • A victim is often unaware of frostbite until someone else points it out because the frozen tissues are numb.

If you detect symptoms of frostbite, seek medical care. Immerse the affected part in warm but not hot water. Take body temperature to see if it is less than 35 °C. If so, treat immediately as hypothermia.


Chilblains is a syndrome of redness and painful blue plaques or nodules associated with burning numbness and intense itching after an exposure to "dry" cold. The skin lesion typically occurs 12 to 14 hours after exposure to cold. Treatment is supportive.



Last revision date: 10 October 2012