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Symptoms and Signs of Heat Cramps

Doctor's Notes on Heat Cramps

Heat cramps are painful, brief muscle cramps that occur during or after exercise or work in a hot environment. Heat cramps are thought to be caused by an electrolyte deficiency.

Symptoms of heat cramps are painful muscle spasms usually involving the legs, chest, or abdomen. The cramps are involuntary, brief, they come and go, and they go away on their own. Heat cramps may be an early sign of serious heat-related illness such as heat exhaustion or heat stroke. Symptoms of heat exhaustion may include sweating, weakness, fast pulse, feeling faint, muscle cramping, nausea, or vomiting. Symptoms of heat stroke include hot, red, dry skin; altered level of consciousness (not acting right), passing out, and extremely high body temperature. Heat stroke is a life-threatening medical emergency. If you suspect heat stroke, call 911 or get to a hospital immediately.

Medical Author: John P. Cunha, DO, FACOEP
Medically Reviewed on 3/11/2019

Heat Cramps Symptoms

Muscle spasms are the only sign of heat cramps. The symptoms of heat cramps are cramps that are:

  • Painful
  • Involuntary
  • Brief
  • Intermittent (they come and go)
  • Usually self-limited (they resolve on their own)

Heat Cramps Causes

The exact cause of heat cramps is unknown, but it is most likely related to electrolyte deficiencies. Various essential minerals, such as sodium, potassium, calcium, and magnesium, are known as electrolytes. They are important for many body functions, and an electrolyte imbalance can cause medical problems.

Sweat contains a large amount of sodium, and drinking fluids with inadequate sodium content after sweating profusely may result in a serious low-sodium condition called hyponatremia.

Those at most risks for heat cramps are:

  • Infants and young children
  • The elderly
  • Individuals who live by themselves or who cannot afford air conditioning in hot environments
  • Those who consume alcohol
  • Individuals who work or exercise in a hot environment
  • Those taking certain prescription medications. Some medications can impair the body's sweat and heat regulation (for example, psychiatric drugs, tranquilizers, OTC cold medications, and antihistamines).
  • People who abuse the drug Ecstasy or other synthetic drugs of abuse.

First Aid Emergencies What Heat Can Do to Your Body Slideshow

First Aid Emergencies What Heat Can Do to Your Body Slideshow

It's your natural cooling system. Your body pushes sweat out onto the surface of your skin. As the air absorbs it (evaporation), it draws heat away and cools you down. This works better in drier climates where humidity is low. You might get very tired and sometimes seriously ill if it doesn't work quickly enough.


Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.