Almost everyone has a “charlie horse” at some point in his or her life. These are muscle spasms in which a group of muscles involuntarily contracts. This causes pain and inability to use the involved muscles.

Stretching them out typically stops the cramp promptly. But soreness may persist for up to a few days.

Often charlie horses develop for no identifiable reason. They can happen while sleeping. Or they may develop due to staying in one position for a long period (as in writer’s cramp).

A variety of conditions are associated with muscle cramps. They include:

• Exercise, especially with dehydration
• Pregnancy
• Kidney disease (especially common among dialysis patients)
• Low potassium (for instance, due to a diuretic drug)
• Low calcium
• Low magnesium
• Hyperventilation (breathing too fast)
• Underactive thyroid
• Certain medicine
• Muscle disease

If your cramps are unexplained, severe, prolonged or frequent, you should see your doctor.

Can you prevent these cramps? It may depend on whether you and your doctor can find a cause. Examples include:

• If you’re getting cramps during exercise: Avoiding dehydration during exercise, replacing lost electrolytes during longer or high intensity exercise, and stretching may help.
• If you have recently started a new medicine that could cause muscle cramps, such as a diuretic: Switching to a different medicine or adjusting the dose may work.
• If you have an underactive thyroid: Taking thyroid pills would likely relieve the cramps.
• If your potassium, calcium or magnesium levels were low: Correcting the reason and taking appropriate supplements may help ease the cramps.