What causes leg cramps? Risk factors and remedies

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Leg cramps occur when muscles in the leg suddenly begin to contract and spasm uncontrollably.

The symptoms of leg cramps depend on their severity. While some people may only feel a minor tic or twitching sensation, others may experience sudden, intense pain and tightness that make it temporarily impossible to use the leg.

The skin over the affected muscles may also visibly twitch or distort, and the area may feel hard.

How long cramps typically last ranges from a few seconds to 15 minutes or more. The cramps may occur several times before they stop entirely, and the affected muscles may continue to feel sore for 24 hours afterward.

Cramps can affect any skeletal muscles, which are those over which people have voluntary control. Leg cramps can occur in several leg muscles, but they most commonly affect the:

• gastrocnemius and soleus muscles, which are at the back of the calf
• quadriceps, at the front of the thigh
• hamstrings, at the back of the thigh

Leg cramps are more likely to occur during the night or a few hours after intense activity, but a person may experience them at any time.

In most cases, leg cramps are not a cause for concern. However, in rare instances, serious underlying conditions may cause muscle cramps, and these conditions will require medical treatment.

Doctors do not know exactly why muscular cramps occur, meaning that they are typically idiopathic, or without a known cause.

However, some researchers think that muscle cramps primarily occur due to one or more of the following causes.

Inadequate stretching and muscle fatigue

Muscle cramps may occur if someone does not properly stretch before intense or prolonged activity, leading to muscle fatigue and an imbalance in the mechanisms that control muscle contraction.

Muscles contain bundles of fibers that contract and expand, allowing muscle movement.

Properly warming up and stretching a muscle lengthens the muscle fibers, allowing them to contract and tighten more intensely during exercise.

Stretching also allows the tendons, which are band-like tissues that connect muscles to bones, to warm up and lengthen. If tendons become too short, they can trigger cramps.

When muscles are not well-conditioned, or a person does not stretch them before intense activity, they are more vulnerable to fatigue, which can change the reflex activity of spinal nerves.

As the muscles become fatigued, they rapidly deplete their oxygen supply, and waste can build up, which can lead to spasms. Once the cramp begins, the altered spinal nerve stimulates it to continue.

For some unknown reason, these altered nerves tend to fire at night, often causing cramps painful enough to wake someone. Stretching tired muscles before bed may help prevent this from happening.

Most cramps related to poor conditioning and overuse go away without medical care.

To help relieve a leg cramp, a person can try:

• stopping the activity
• holding the leg in a stretched position
• gently massaging the cramping muscle
• resting

Dehydration

During exercise, the body sweats to release excess heat, which removes water and important salts and minerals called electrolytes.

Exercising in a warm environment or just doing daily activities in a hot or humid climate increases the rate of sweating and the risk of dehydration.

When the body loses too much water or electrolytes, muscle cramps can occur.

Tips for treating muscle cramps due to dehydration or electrolyte imbalances include:

• moving to a cool, shaded, well-ventilated area
• drinking plenty of fluids even if not thirsty — ideally plain water or fluids rich in electrolytes, which include many sports drinks, electrolyte packets that dissolve in water, and most natural juices
• resting and trying to avoid overheating

Other causes

Scientists think that most cramps occur due to poor conditioning and muscle fatigue or dehydration and electrolyte imbalances. However, the following causes may also trigger muscle cramps:

• sudden restrictions in blood flow to the muscles, which cause oxygen depletion and waste buildup
• compressed nerves
• pregnancy, during which extra body weight can strain the leg muscles
• liver disease, which can cause toxins to build up in the blood
• toxin exposure, which can allow poisonous substances to accumulate in the blood or muscles
• infection, which can cause bacteria and their toxic byproducts to build up in the blood or muscles
• certain neurological conditions that affect muscle control, such as peripheral neuropathy, amyotrophic lateral sclerosis (ALS), or motor neuron disease
• diuretic medications that can dehydrate the body or make it more vulnerable to dehydration
• statins and nicotinic acid medications that alter the levels of cholesterol in the blood
• thyroid disease, which alters metabolism
• hormone conditions
• nutritional deficiencies

People who experience leg cramps that are not due to inadequate stretching and muscle fatigue or dehydration and electrolyte imbalances often require medical care to treat the underlying condition.

However, people can generally relieve most cramps to some extent with home remedies, such as stretching, massage, and cold or heat therapy.

If leg cramps occur as a result of using a medication, a doctor may suggest a different dosage or an alternative medication.

Pregnancy-related leg cramps should resolve after the person gives birth and starts to return to their original weight. A pregnant person may relieve cramps by resting the muscles or stretching them frequently throughout the day.

If toxins are responsible for a person’s leg cramps, a doctor may need to prescribe intravenous therapy and antibiotics.

Muscle relaxants can treat leg cramps related to a lack of muscle control or liver disease. In extreme cases, healthcare providers may give someone quinine, an antimalarial drug that tends to reduce cramping.

If someone’s leg cramps are due to the compression of a nerve, blood vessel, or muscle, they may require emergency medical care and surgery.

A few at-home remedies may help reduce symptoms while cramps are occurring.

The best way to stop a muscle from cramping is to straighten and stretch the affected muscle.

For example, if the cramp is affecting the calf, a person can straighten the leg and lift the foot upward while bending the ankle so that the toes point toward the shins.

Other at-home remedies for leg cramps include:

• applying ice or cold packs wrapped in cloth to sore or tender muscles for 20-minute intervals
• applying heat pads or packs to tight, tense muscles
• taking over-the-counter pain relief medication or muscle relaxants, if pain continues after the cramp
• walking on the heels, if cramping affects the calf muscles
• using a foam roller or muscle roller
• massaging the affected muscles and those around them
• resting the legs

Some people are more prone than others to leg cramps. The cramps may develop even when a person is inactive.

However, people can take steps to help reduce the risk of cramping. These include:

• warming up properly before exercise, such as by walking briskly for a few minutes
• stretching the leg muscles properly before exercise, making sure to stretch the calves, hamstrings, quadriceps, and muscles of the feet
• stopping activity if pain or exhaustion begins
• staying hydrated, especially when exercising or in a warm environment
• avoiding exercising in very warm, humid conditions
• stretching the leg muscles frequently throughout the day and before bed

In most cases, leg cramps are harmless and go away without medical care.

However, people should talk to a doctor if they experience cramps that are:

• frequent
• severe
• prolonged, meaning that they last longer than 10 minutes
• disabling after the cramping stops
• not related to exercise or heat
• potentially related to infection, toxic exposure, or organ disease
• unresponsive to home remedies

Leg cramps are typically harmless and resolve randomly or with the use of home remedies.

People can sometimes prevent leg cramps, primarily by stretching before exercise, throughout the day, and before bed.

It is important to talk to a doctor about leg cramps that are more intense, severe, or frequent than normal or do not respond to at-home treatments.