Common causes of severe leg cramps include muscle strain, pregnancy, exposure to cold, mineral deficiencies, dehydration, certain medications and underlying medical conditions, according to WebMD. Additionally, leg cramps are sometimes caused by poor blood circulation in the legs and malfunctioning nerves, particularly in the neck or back.
Leg cramps can occur as a result of various conditions related to use of the muscles, including overexertion while exercising, not properly stretching before exercising, muscle fatigue due to overuse, and injury, relays WebMD. Muscle cramps are sometimes caused by deficiencies in certain minerals, such as magnesium or potassium, in the blood. Calcium deficiency is common in pregnant women, especially in the later months of the pregnancy.
Underlying medical conditions, such as peripheral arterial disease, kidney disease, thyroid disease and multiple sclerosis, frequently cause leg cramps, according to WebMD.
Another possible cause for leg cramps is lumbar stenosis, which is compression of nerves in the spine. Persons with arteriosclerosis of the extremities suffer from narrowing of the arteries that supply blood to the lower legs and often experience leg cramps while exercising, reports Mayo Clinic.
Muscle cramps are also a side effect of some medications. Diuretics, certain asthma medications, statins for cholesterol, antipsychotics, birth control pills and steroids can cause cramping, according to WebMD.