A cramp is an unpleasant sensation caused by contraction, usually of a muscle. It can be caused by cold or overexertion. Illness or poisoning can also cause cramps, particularly in the stomach, which is referred to as colic if it fits particular characteristics.

Menstruation also is highly likely to cause cramps of varying severity in the abdomen. Most of this is attributable to the passing of coagulated blood through the cervix.

Electrolyte disturbance may cause cramping and tetany of muscles, particularly hypokalemia (a lack of potassium) and hypocalcemia (a lack of calcium).