Cramps, or muscle spasms. The most frequent clinical site is the spasm of the gastrocnemius muscle, which means calf cramps, followed by twitching of the hands and spasms of the whole body. The main manifestation is the contracture of the smooth muscles of the body. If the smooth muscles of the gastrointestinal tract spasm, it will cause abdominal pain and vomiting; if the smooth muscles of the bronchial tract spasm, it will cause asthma; if the smooth muscles of the larynx spasm, it will cause asphyxia or apnea; if the smooth muscles of the arterial vessels spasm, it will cause symptoms of increased blood pressure and insufficient blood supply. There are many causes of muscle spasms, and low calcium is one of the common causes. Calcium ions are involved in the body’s neuromuscular excitation and contraction process, and calcium deficiency tends to cause increased neuromuscular excitability and muscle spasms. Most of the symptoms such as calf cramps in pregnant women, mothers and elderly people, and hand and foot twitching in infants and children are caused by calcium deficiency. However, the causes of cramps are not limited to calcium deficiency, but there are many other causes, such as seizures, hypoglycemia, hyperthermia, cranial trauma, cerebrovascular accidents, brain infections, drug poisoning, hypertension in pregnancy, hysteria, tetanus, rabies, and food poisoning, etc. Therefore, cramps should be checked by a hospital early to exclude other diseases so as not to delay the treatment. The cramps caused by these diseases can lead to irreversible damage to the brain if they are prolonged. Cramps caused by calcium deficiency can be quickly relieved by calcium supplementation or calcium treatment.