Heat Cramps

Medically Reviewed by Tyler Wheeler, MD on February 28, 2024
Written by WebMD Editorial Contributors
2 min read

Heat cramps are painful, brief muscle cramps. Muscles may spasm or jerk involuntarily. Heat cramps can occur during exercise or work in a hot environment or begin a few hours later.

Heat cramps usually involve muscles that are fatigued by heavy work, such as calves, thighs, and shoulders.

  • You are most at risk if you are doing work or activities in a hot environment -- usually during the first few days of an activity you're not used to.
  • You are also at risk if you sweat a great deal during exercise and drink large amounts of water or other fluids that lack salt.

 

The exact cause of heat cramps is unknown. They are probably related to electrolyte problems. Electrolytes include various essential minerals, such as sodium, potassium, calcium, and magnesium. They are involved in chemical reactions in your muscles. An imbalance can cause problems.

Sweat contains a large amount of sodium, and drinking fluids with inadequate sodium content may result in a serious low-sodium condition called hyponatremia. Some factories have virtually eliminated heat cramps in their workers by supplying salt-enriched fluids.

Muscle spasms that are:

  • Painful
  • Involuntary
  • Brief
  • Intermittent
  • Usually self-limited (go away on their own)

Heat cramps can be quite painful. Consider seeking medical attention if the symptoms do not go away with rest and after restoring fluid and electrolytes.

Call your doctor if these conditions develop:

  • If you are unable to drink sufficient fluids because you have nausea or are vomiting, you may need IV rehydration with normal saline.
  • Heat cramps may accompany heat exhaustion.
  • If you have more severe symptoms of heat illness, including dizziness, fatigue, vomiting, headache, fast heartbeat, shortness of breath, or a high temperature (greater than 104 degrees), get immediate medical care.

The doctor will check you for more severe heat illness and possibly provide you with IV fluid rehydration.

Heat cramps usually go away on their own, but you can try one of these home remedies:

  • Rest in a cool place and drink a sports drink, which has electrolytes and salt, or drink cool water.
  • Make your own salt solution by mixing 1/4 to 1/2 teaspoon table salt dissolved in a quart of water.

Salt tablets by themselves should not be used. They can cause stomach upset and don't adequately replace fluid volume lost.

If you work in a hot environment, you may experience heat cramps during the first few days on the job. Once you get used to the environment, and make sure you have adequate fluid replacement, you are less likely to have problems.