Cramp is a sudden contraction, or spasm, of the muscles which is accompanied by a "knotting" pain.

Cramp can strike at any time, but it most often occurs at night after turning or stretching during sleep. Cramp usually occurs in the calf muscles, which become hard and tense.

Cramp can affect people of all ages, but is particularly common in people over 50.


Inside every muscle are hundreds of muscle fibres and each of these contain muscle filaments. These slide past each other when the muscle is relaxed.

When the muscle needs to generate force (in order to walk, run or kick) the filaments lock together and the muscle contracts. A signal is given to the muscle and it is washed with a salt (sodium) solution. The filaments then need to unlock and relax before contracting again. In this case the filaments are washed with a calcium solution, relaxing the fibres as you propel forwards. Muscle fibres are therefore in a continuous cycle of contraction and relaxation.

However, painful cramp is out of control muscle contraction, locking the muscle in a very painful spasm, which can often last for several agonising minutes...or a lot longer.

Many muscles are attached to more than two bones. Muscles are arranged opposite each other, e.g. the muscles in the shin of our leg allow us to bend our ankle upward, while the calf muscle allows us to bend our ankle downward.

Cramp can be caused by any one of a number of factors such as

poor circulation,
muscle tightness,
poor posture,
taking certain medicines
or a calcium deficiency.
Dehydration, especially after exercise, can also cause cramp when a chemical imbalance in the muscle makes it suddenly contract. Again, the calf muscles are the most frequently affected during or after exercise.

Drinking plenty of water before, during and after exercise will help prevent cramp.

Don't wait until you feel thirsty to start drinking, as thirst is a sign that you have already become dehydrated.

Warming up and gently stretching your muscles before exercise helps to avoid cramp.

It is also a good idea to warm down after completing any exercise programme by doing five to ten minutes of stretching exercises.

Stretching Exercises:

Hamstring Muscle Stretch - Sit with one leg folded in and the other leg straight out, foot upright with toes and ankles relaxed. Lean forward slightly and touch your foot of your straightened leg. Repeat with your opposite leg.

Calf Muscle Stretch - Start with a standing lunge with both your feet pointed forward, then straighten your rear leg out behind you. Repeat with your opposite leg.

Quadriceps Muscle Stretch - While standing, hold the top of your foot with your opposite hand and gently pull your heel towards your buttocks. Repeat with your opposite leg.

Hold each stretch briefly for a few seconds, then release . Never stretch to the point of pain.

There are over 13 million people in the UK who regularly suffer from leg cramps at night1, preventing them from sleeping.

Some unfortunate people may experience one or two episodes nightly, several times a week. The soreness in the affected muscle may then last well into the next day.

Local massage, heat, or movement of the affected limb may help to both treat and actually temporarily relieve the pain, but Crampex tablets taken before going to bed at night may help to both treat and actually prevent nocturnal cramp.

Tips on managing cramp:
When you are having an attack of cramp, rubbing the muscle vigorously and stretching it gently will help bring relief.

You may also find it useful to place a hot wet towel over the area affected as soon as the cramp has eased, or while it is still easing.

Repeat this every five minutes, for about four or five times in total, and then gently move the affected muscle, by walking or stretching.

Ideas for preventing cramp:
Stretch your calf muscles. Stand about two feet away from a wall, keeping your heels flat and your legs straight. Lean towards the wall as you support yourself with your hands. Hold for 10 to 15 seconds and repeat ten times.
Massage your calves by rubbing from the ankle upwards - five minutes on each leg.
Use an electric blanket on cold winter nights. This can keep the calf muscles warm and pain free.
Sleep on your side with knees bent and a pillow between them.
Sleeping on your stomach with your legs straight out makes the calves more prone to cramping.
Loosen your night covers and wear roomy pyjamas. The pressure of heavy blankets and tight pyjamas could be partly to blame for muscle cramps.
Take regular exercise. Walking, swimming and cycling are excellent.
Yoga is also a good way of learning to relax and stretch your muscles.

Can vitamin deficiencies cause muscle cramps?
Several vitamin deficiency states may directly or indirectly lead to muscle cramps. These include deficiencies of thiamine (B1), pantothenic acid (B5), and pyridoxine (B6). The role of deficiency of these vitamins in causing cramps is unknown.

Can poor circulation cause muscle cramps?
Poor circulation to the legs, which results in inadequate oxygen to the muscle tissue, can cause severe pain. This commonly occurs in the calf muscles.

Can inadequate stretching and muscle fatigue cause muscle cramps?
Muscles are bundles of fibres that contract and expand to produce movement. A regular program of stretching lengthens muscle fibres so they can contract and tighten more vigorously when you exercise. When your body is poorly conditioned, you are more likely to experience muscle fatigue, which when coupled with overexertion depletes a muscle's oxygen supply, leading to build up of waste product and spasms. This can then lead to cramps as the muscle fibres cease to contract and expand effectively.

What are the other causes of muscle cramps?
Cramp can be caused by any one of a number of factors such as poor circulation, tiredness, muscle tightness, poor posture, taking certain medicines or a calcium deficiency. Dehydration, especially after exercise, can also cause cramp when a chemical imbalance in the muscle may make it suddenly contract.

Who gets muscle cramps?
Just about everyone will experience a muscle cramp sometime in life. It can happen while you play tennis or golf, bowl, swim or do any exercise. It can also happen while you sit, walk or even just sleep. Sometimes the slightest movement that shortens a muscle can trigger a cramp. Some people are pre-disposed to muscle cramps and get them regularly with any physical exertion. Those at greatest risk for cramps include infants and young children, people over the age of 50, and those who are ill, overweight, overexert during work or exercise, or take drugs or certain medications. There are over 13 million people in the UK who regularly suffer from leg cramps at night, preventing them from sleeping. (Postgraduate Medicine February 2002).

Are there any medicinal products available over-the-counter I can take to help alleviate my muscle cramps?
Yes. Crampex Tablets is the ONLY medicine licensed in the UK for the treatment of muscle cramps at night.

Can Crampex Tablets prevent cramp?
Yes. Cramps normally occur in spells lasting from a few days to a few weeks. Crampex tablets should be taken with a drink before bedtime each day for as long as you think the attacks will last.

When shouldn't I take Crampex?
If you are taking any medicine for heart or circulation problems, speak to your doctor or pharmacist before taking Crampex tablets. If you suffer from kidney problems or high blood pressure, again consult your doctor before using this product.

Can Crampex be taken by children?
Crampex tablets can be taken by adults and the elderly but are not recommended for children.

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This page was last updated: Monday 25 September, 2017