Leg cramps are common. The cause is not known in most cases. However, some medications and diseases sometimes cause leg cramps. Regular calf stretching exercises may prevent leg cramps. Quinine tablets may be advised as a last resort if you have cramps regularly.

What are leg cramps?
A leg cramp is a pain that comes from a leg muscle. It is due to a muscle spasm, which occurs when a muscle contracts too hard. It usually occurs in a calf muscle, below and behind a knee. The small muscles of the feet are sometimes affected.

A cramp pain typically lasts a few minutes. In some cases it lasts just seconds; however, in some cases it lasts up to 10 minutes. The severity of the pain varies. The muscle may remain tender for up to 24 hours after a leg cramp. Leg cramps usually occur when you are resting - most commonly at night when in bed. (They are often called night cramps.) They may wake you. It can become a distressing condition if your sleep is regularly disturbed.

Who has leg cramps?
Many people have an occasional leg cramp. However, they occur frequently in some people. They are more common in older people. About 1 in 3 people over the age of 60 and about half of people over the age of 80 have regular leg cramps. About 4 in 10 people who have leg cramps have at least three per week. They occur every day in some people.

What causes leg cramps?
Unknown cause (idiopathic leg cramps)
In most cases the cause is not known. One theory is that cramps occur when a muscle that is already in a shortened position is stimulated to contract. As the muscle is already shortened, to contract further may cause the muscle to go into spasm. This commonly happens at night in bed, as the natural position we lie in is with the knees slightly bent (flexed) and with feet pointing slightly downwards. In this position the calf muscle is relatively shortened and may be prone to cramps. This theory explains why stretching exercises may cure the problem.