Heat Illness Prevention


Heat illness is a broad term for heat-related injuries and illnesses. This fact sheet provides information on a variety of heat-related illnesses, signs and symptoms of each, and precautions that should be taken to prevent heat illnesses.


What Is Heat Illness?

Heat illness is a broad term for several heat-related injuries and illnesses. The following are some of the more common heat illnesses:

  • Heat rash, also known as prickly heat, usually occurs when sweat from the body is not readily removed from the surface of the skin by evaporation. Heat rash can be a relatively mild irritant or, if it becomes infected, can be so uncomfortable that it can affect sleep and performance of duties.
  • Heat cramps are painful spasms of the muscles. These cramps are caused by a lack of electrolytes within the body.
  • Heat exhaustion is caused by lack of hydrating fluids that need to be replaced during heavy exertion. Heat exhaustion can cause an increase in core body temperature and can lead to heatstroke.
  • Heatstroke is the most serious heat-related problem and is life threatening. The body of a heatstroke victim no longer has the ability to regulate core body temperature. This condition requires immediate medical assistance.

When Heat Illness Is an Issue

  • Persons are at increased risk of heat illness during heavy exertion or when working in uncomfortable temperatures.
  • Heat illness can occur indoors or outdoors but tends to be more common outdoors.
  • Persons new to a warm climate or returning to one are particularly at risk for heat illness. They should take time to acclimatize before strenuous activity, if possible.

Initial Symptoms of Heat Illness

  • Heat cramps are usually the first stage of heat-related illness.
  • Additional symptoms of heat illness include heavy sweating, tiredness, weakness, dizziness, headache, nausea, and fainting.
  • Victims may experience only one of these symptoms or many.
  • If you suspect you have some of these symptoms, do not ignore them. Treat them immediately.

Preventing Heat Illness

  • It is best to prevent heat illness so that it does not occur.
  • During hot weather, drink more liquid than thirst indicates. Increase fluid intake, regardless of activity level. Urine should be clear or lightly colored.
  • Provide drinking water in convenient, visible locations to drink often and as needed. One quart per hour per person is the minimum.
  • Keep sufficient first-aid supplies available to treat dehydration and heatstroke. Supplies for intravenous rehydration should also be on hand when emergency medical services are not immediately available.
  • Use shaded areas for rest periods. The warmer the temperature and the harder the exertion, the more frequent the rest periods should be. Preventive rest periods should be made available whenever someone feels in need.
  • Try to accomplish the hardest activities in the cooler temperatures of the day.
  • Wear the right protective clothing for the activity.
  • Never ignore heat illness–related symptoms.
  • Remember that infants and children, people 65 years of age and older, people who are overweight, and people who are ill or on certain medications are at the greatest risk for heat-related illness.