Muscle spasms often occur when a muscle is overused or injured. Things that might bring on a muscle spasm include:

• Exercising when you have not had enough fluids (you're dehydrated).
• Having low levels of minerals such as potassium or calcium.

Some spasms occur because the nerve that connects to a muscle is irritated. One example is when a herniated disk irritates the spinal nerves and causes pain and spasm in the back muscles.

Spasms in the calf often occur while kicking during swimming or running. They can also happen at night when you are in bed. Upper leg spasms are more common with running or jumping activities. Spasm in the neck (cervical spine) can be a sign of stress.

When a muscle goes into spasm it feels very tight. It is sometimes described as a knot. The pain can be severe.

To diagnose a spasm, your health care provider will look for tight or hard muscles that are very tender to the touch. There are no imaging studies or blood tests for this condition. If the spasm is caused by nerve irritation, such as in the back, an MRI may be helpful to find the cause of the problem.

Stop your activity and try stretching and massaging the affected muscle at the first sign of a spasm.

Heat will relax the muscle at first. Ice may be helpful after the first spasm and when the pain has improved.

If the muscle is still sore after heat and ice, you can use nonsteroidal anti-inflammatory medicines (such as ibuprofen or naproxen) to help with pain. In more severe cases, your provider can prescribe antispasm medicines.

After you get treated, your provider should look for the cause of the spasm so that it doesn't happen again. If an irritated nerve is involved, you might need physical therapy or even surgery.

Drinking water or sports drinks when exercising can help ease cramps due to dehydration. If drinking water alone is not enough, salt tablets or sports drinks may help replace minerals in your body.

Muscle spasms will get better with rest and time. The outlook is excellent for most people. Learning how to exercise properly with the right training and enough fluid intake can prevent spasms from occurring regularly.

You might need other treatments if an irritated nerve caused the spasm. Results from these treatments can vary.

Call your provider if:

• You have a muscle spasm with severe pain.
• You have weakness with your muscle spasm.
• You have a muscle spasm that does not stop and it spreads to other parts of the body.

Even if your spasms are not severe, your provider can help you change your exercise program to reduce the risk of spasms in the future.

Things you can do to lessen the chance of muscle cramps include:

• Stretch to improve your flexibility.
• Change your workouts so that you are exercising within your ability.
• Drink plenty of fluids while exercising and increase your potassium intake. Orange juice and bananas are great sources of potassium.

Muscle spasm

Geiderman JM, Torbati S. General principles of orthopedic injuries. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 41.

Wang D, Eliasberg CD, Rodeo SA. Physiology and pathophysiology of musculoskeletal tissues. In: Miller MD, Thompson SR. eds. DeLee, Drez, and Miller's Orthopaedic Sports Medicine. 5th ed. Philadelphia, PA: Elsevier; 2020:chap 1.

Updated by: Linda J. Vorvick, MD, Clinical Professor, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.