A cramp is a painful and strong contraction or a tightening of a muscle that occurs suddenly.

Leg cramps are common and usually harmless.

Various studies have reported that leg cramps occur in three out of four people at night; one out of five people during the day and night; and one out of 14 people during the day.

The cause of leg cramps may be unknown (idiopathic), due to an underlying condition or as a side effect of medicines.

While the cause of idiopathic leg cramps is, as mentioned above, unknown, it has been attributed to excessive strain, e.g. during exercise; abnormal nerve activity during sleep; and sudden decrease in blood supply to the affected muscles.

Muscles are connected to bone by bands of tissue called tendons. With increasing age, tendons tend to shorten and may cause leg cramps in the muscles connected to them, particularly if the tendons become too short.

There are many conditions that can cause leg cramps.

The extra weight, as well as deficiency of calcium and/or magnesium, in pregnancy can lead to strain on the leg muscles, causing cramps.

Leg cramps are common after exercise, and can sometimes occur during dehydration when salt levels in the body decrease.

They can also occur when one stands on a hard surface or sits for a long time; or when there is a deficiency in blood levels of potassium, calcium and other minerals.

Leg cramps can occur in liver, kidney, thyroid and/or peripheral arterial disease; some bacterial infections, e.g. tetanus; and when there are increased blood levels of toxic substances, e.g. lead or mercury.

Some medicines are known to cause leg camps in a small number of people.

These medicines include diuretics, which are used in the treatment of high blood pressure, heart failure and some types of kidney disease; statins and/or nicotinic acid, which are used to treat high blood cholesterol; nifedipine, which is used to treat angina; and raloxifene, which is used to prevent osteoporosis in menopausal women.

Although leg cramps can affect any part of the leg, it usually affects the calf muscles, i.e. the muscles at the back of the leg below the knees.

Although less common, it can also affect the feet and thighs.

During the cramp, the affected muscles are painful, tight and stiff.

Cramps can last a few seconds to up to ten minutes, with thigh cramps tending to last longer than the other types.

After the cramps, the leg may be painful and tender to touch for up to a few hours.

What to do

If the leg cramps occur occasionally, it is not of concern.

However, a consultation with the doctor is advisable if the cramps are frequent or so painful that it affects daily activities, or if the legs are weak or are getting smaller in size.

Immediate medical attention should be sought if the cramps lasts more than 10 minutes and do not improve with exercise; or the cramps occur after contact with poisons, e.g. lead or mercury; or infections, e.g. a cut contaminated with soil.

Leg cramps due to medical conditions or medicines are treated by managing the cause.

Idiopathic leg cramps are treated by exercise and painkillers.

Exercises can be done during the cramps or as a preventive measure to reduce the frequency of cramps.

During the cramp, the affected muscle can be stretched and massaged.

For example, if the cramps are in the calf, the legs can be straightened with the foot lifted upwards and bent at the ankle, added with a walk about on the heels for a few minutes.

A warm shower or bath, or the application of a heat pad can relax the muscles.

Leg pain after cramps can be reduced with over-the-counter (OTC) painkillers like paracetamol or ibuprofen.

It is essential to follow the instructions on the label of the medicine if OTC medicine is used.

If the painkiller has been prescribed by the doctor, the instructions given must be adhered to.

An abundant intake of oral fluids is often helpful.

A number of measures can be taken to prevent or reduce the frequency of cramps.

They include abundant intake of oral fluids; consumption of foods that are rich in calcium, potassium and magnesium; daily multivitamin supplementation; and avoidance or reduction of alcohol intake.

Exercises that stretch the affected muscles thrice daily for about 5-10 minutes are useful.

It is important that any increase in the amount of exercise is gradual.

If the cramps are due to medicines, alternative medicines will be prescribed.

Medication for leg cramps 

Quinine, an antimalarial medicine, has been found to be moderately effective in reducing the frequency of leg cramps.

However, it is known to have a small likelihood of side effects, some of which may be life-threatening.

As such, quinine is only prescribed by the doctor if the benefits outweigh the risks, i.e. exercise has not helped or the frequency of the cramps impact on the quality of life.

Quinine has to be consumed as instructed by the doctor.

The doctor will monitor and review the management plan regularly, which will be for a period that will be discussed with the patient.

This involves keeping a diary that records the frequency and severity of the cramps.

Improvements will lead to a reduction in the frequency of monitoring, and ultimately, cessation.


Dr Milton Lum is a past president of the Federation of Private Medical Practitioners Associations and the Malaysian Medical Association. The views expressed do not represent that of organisations that the writer is associated with. The information provided is for educational and communication purposes only and it should not be construed as personal medical advice. Information published in this article is not intended to replace, supplant or augment a consultation with a health professional regarding the reader’s own medical care. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.