A cramp is a sudden, involuntary muscle contraction or overshortening; while generally temporary and non-damaging, they can cause significant pain and a paralysis-like immobility of the affected muscle. Muscle cramps are common and are often associated with pregnancy, physical exercise or overexertion, age, or may be a sign of a motor neuron disorders. Cramps may occur in a skeletal muscle or smooth muscle. Skeletal muscle cramps may be caused by muscle fatigue or a lack of electrolytes such as sodium, potassium, or magnesium. Some skeletal muscle cramps do not have a known cause. Cramps of smooth muscle may be due to menstruation or gastroenteritis. Motor neuron disorders, metabolic disorders, some medications, and haemodialysis may also cause muscle cramps.
