Sudden muscle spasms in which a muscle or group of muscles becomes hard, painful, and tight often occur during physical exercise. Another common cause is sitting or lying in an awkward position.
Certain medications may also cause cramps, and cramps may sometimes be a symptom of an underlying disorder.
Often, however, there is no apparent cause.
Stretching or massaging the affected muscle usually relieves cramps.
For severe or recurrent cramps, a doctor may prescribe a muscle relaxer or quinine (an antimalarial drug that can also relieve cramp) and investigate possible causes.