A muscle cramp is a strong, painful contraction or tightening of a muscle that comes on suddenly and lasts from a few seconds to several minutes. It often occurs in the legs. A muscle cramp is also called a charley horse.

Nighttime leg cramps are usually sudden spasms, or tightening, of muscles in the calf. The muscle cramps can sometimes happen in the thigh or the foot. They often occur just as you are falling asleep or waking up.

The cause of muscle cramps isn’t always known. Muscle cramps may be brought on by many conditions or activities, such as:

• Exercising, injury, or overuse of muscles.
• Pregnancy. Cramps may occur because of decreased amounts of minerals, such as calcium and magnesium, especially in the later months of pregnancy.
• Exposure to cold temperatures, especially to cold water.
• Other medical conditions, such as blood flow problems (peripheral arterial disease), kidney disease, thyroid disease, and multiple sclerosis.
• Standing on a hard surface for a long time, sitting for a long time, or putting your legs in awkward positions while you sleep.
• Not having enough potassium, calcium, and other minerals in your blood.
• Being dehydrated, which means that your body has lost too much fluid.
• Taking certain medicines, such as antipsychotics, birth control pills, diuretics, statins, and steroids.

You may need to try several different ways to stop a muscle cramp before you find what works best for you. Here are some things you can try:

• Stretch and massage the muscle.
• Take a warm shower or bath to relax the muscle. A heating pad placed on the muscle can also help.
• Try using an ice or cold pack. Always keep a cloth between your skin and the ice pack.
• Take an over-the-counter pain medicine, such as acetaminophen(Tylenol), ibuprofen (Advil, Motrin), or naproxen (Aleve). Be safe with medicines. Read and follow all instructions on the label.
• If your doctor prescribes medicines for muscle cramps, take them exactly as prescribed. Call your doctor if you have any problems with your medicine.
• Drink plenty of fluids. Sports drinks, such as Gatorade, will often help leg cramps.

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