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Muscle Cramps

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PatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.

See also: Cramps in the Leg written for patients

Muscle cramps are very common and 'cramp' is usually taken to mean 'a spasmodic, painful, involuntary contraction of skeletal muscle'. This transient, involuntary episode of pain is usually brief (<10 minutes). The lower limbs are almost invariably involved. However, no single accepted definition of muscle cramp exists and many classifications of muscular cramps have been attempted.

There are many causes. Cramps can be grouped according to their underlying aetiology:

  • Paraphysiological cramps
  • Symptomatic cramps
  • Idiopathic cramps

When patients complain of cramps it is important to clarify exactly what they mean, as the term is frequently used to describe any muscular 'tightness'.

Groups at increased risk:

  • Up to 60% of adults report that they have had nocturnal leg cramps.[1]
  • The problem is often distressing, impacting on sleep, and has an adverse effect on quality of life.
  • Pregnant women - up to 30% of women can be affected by leg cramps during pregnancy.[2]
  • Muscle cramps are common in children, especially at night.
  • Those with metabolic disorders; for example, 50% of patients with uraemia and 20-50% of those with hypothyroidism complain of muscle cramps.[3]
  • Athletes and individuals working under hot conditions - eg, firemen.

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Find out what the patient means by cramps:

  • Where do they occur?
  • When do they occur?
  • How often do they occur?
  • How long do they last?
  • Is there any other relevant medical history such as thyroid disease or cardiovascular disease?
  • Are drugs taken? For example, diuretics, salbutamol, nifedipine.
  • Ask about alcohol consumption.
  • Ask about sport.

Most often, cramps involve the calf or thigh muscles and small muscles of the foot. Of these, the most commonly affected is the calf and it tends to be unilateral.

Cramps occur at rest and usually at night. The most likely explanation is that leg cramps occur when a muscle that is already in a shortened position is involuntarily stimulated. This commonly happens at night where the plantar flexed foot places the calf and ventral foot muscles in the most shortened and vulnerable position. The cramp may last seconds or minutes but post-cramp tenderness may last up to 24 hours.

  • During an attack the affected muscle or group is hard and tender.
  • Between attacks examination is unlikely to be rewarding.
  • The muscle may be tender for up to 24 hours after the previous attack.
  • In the elderly or where peripheral arterial disease is suspected, check for peripheral pulses and capillary refill.
  • Look for signs of neurological disease - eg, muscle wasting and fasciculations, altered reflexes, sensory or power loss.
  • Paraphysiological cramps occur in healthy people in response to a physiological stimulus. They are very common and may occur during sport or in unaccustomed exercise. They are especially likely to occur during endurance sports.
  • They are thought to result from hydro-electrolyte imbalance following repeated and chronic use of the same muscle group, producing increased excitation of the neuromuscular nerve endings.[4]
  • It is thought that low levels of magnesium and other electrolytes may also play a part.
  • They are also very common in pregnancy. The aetiology in pregnancy is unknown: pressure on nerves and blood vessels, circulatory changes and low levels of calcium and magnesium have all been suggested.
  • They may also occur in healthy individuals as a result of a sustained posture over a prolonged period of time.

Cramps may also occur in association with metabolic disturbance, including:

One or more of these may be the underlying aetiology in many of the causes listed below. Blood tests measure the extracellular environment but do not reflect the intracellular fluid which is probably more important.

  • Arterial insufficiency.
  • Acute or chronic diarrhoea.
  • Excessive heat and sweating causing Na+ depletion.
  • Hypothyroidism (associated with weakness, enlarged muscles and painful muscle spasms).
  • Hyperthyroidism (associated with myopathy).
  • Lead poisoning.
  • Sarcoidosis.
  • Hyperparathyroidism (hypercalcaemia).
  • Heavy alcohol ingestion and cirrhosis.
  • Hyperventilation-induced respiratory alkalosis.
  • Haemodialysis.
  • Parenteral nutrition.
  • Lower motor neurone disorders including amyotrophic lateral sclerosis, polyneuropathies, recovered poliomyelitis, peripheral nerve injury and nerve root compression.

Drugs causing cramps

Always exclude a medicine-related cause. Implicated drugs include:
  • Salbutamol and terbutaline
  • Raloxifene
  • Opiate withdrawal
  • Diuretics cause electrolyte loss
  • Nifedipine
  • Phenothiazines
  • Penicillamine
  • Nicotinic acid
  • Statins

This is a diagnosis of exclusion but represents the majority of sufferers. Familial forms exist which appear to have an autosomal dominant mode of transmission.[5] This group also contains conditions such as idiopathic nocturnal cramps and fasciculation-cramp syndrome.


Usually no investigation is indicated. They may be performed if an underlying cause is suspected.

Potential investigations include:

  • U&Es
  • LFTs
  • TFTs
  • Serum calcium or magnesium
  • Creatine kinase
  • Lead levels
  • Doctors and patients can use Decision Aids together to help choose the best course of action to take.
  • Compare the options  


  • In most cases the aetiology is benign and the patient needs to be reassured of this whilst steps are taken to help alleviate the problem. Exclude known causes of muscle cramps without excessive and unnecessary investigation.
  • Management depends upon the cause of the problem. Review drugs. Address any correctable problems - eg, use of diuretics and electrolyte imbalance.
  • The severity of symptoms and their impact on sleep, mood, and quality of life will determine whether treatment is required. Asking patients to keep a sleep and cramp diary may be helpful to assess progress.[6]
  • The evidence base for management of this common but usually benign condition is not strong.



  • Passive stretching and massage of the affected muscle will help ease the pain of an acute attack - eg, for calf cramping, straighten the leg with dorsiflexion of the ankle or heel walk until the acute pain resolves.
  • Regular stretching of the calf muscles throughout the day may help to prevent acute attacks. Some people recommend stretching three times daily whilst others advocate stretching before going to bed.
  • Using a pillow to raise the feet through the night, or raising the foot of the bed may help to prevent attacks in some people.
Diagram of a Stretching Exercise

Note that whilst stretching exercises are unlikely to do harm, evidence for their efficacy is contradictory. In sport, stretching is widely advocated as likely to reduce injury and cramp but the quality of evidence tends to be poor, with failure to distinguish benefit from that due to improvement in physical fitness from training.[7] Avoiding over-training and risky conditions (eg, hot and humid environmental conditions) can be useful in preventing cramps.[8]

The value of massage, over and above psychological benefit, is also questioned.[9]


  • Quinine sulfate has been the most frequently used drug in the UK for the treatment of leg cramps in non-pregnant individuals who have not responded to conservative measures.
  • However, it is not generally recommended due to the poor benefit-to-risk ratio. The Food and Drug Administration (FDA) in America has banned the use of quinine for this indication.
  • Quinine has an extensive side-effect profile, including thrombocytopenia as an important but rare complication. Evidence for its long-term efficacy is lacking.
  • However, a Cochrane review found that there was moderate evidence that quinine significantly reduces cramp frequency, intensity and cramp days in dosages between 200 and 500 mg/day. There was moderate evidence that with use up to 60 days, the incidence of serious adverse events was not significantly greater than for placebo in the identified trials.[10]
  • A therapeutic trial approach may be used where self-care measures fail and leg cramps are frequent and affecting the person's quality of life:[3][11] 
    • Prescribe 200-300 mg nocte for 4-6 weeks.
    • Monitor using a sleep and cramp diary.
    • If helpful, continue treatment for three months, then stop to reassess ongoing need.
    • If ongoing treatment is required, regular medication reviews should occur every 3-6 months.
  • Quinine can frequently be stopped without a recurrence of troublesome symptoms.[12]
  • Potential drug alternatives to quinine include verapamil and gabapentin in the general population and vitamin E or L-carnitine in the dialysis population.[13][14]
  • Avoid quinine in pregnancy and concentrate on nondrug measures where possible. Calcium lactate is ineffective but magnesium supplements may help relieve the symptoms in pregnant women who have not responded to conservative measures.[15]
  • Traditionally, sodium chloride has been thought to be beneficial, although the trial evidence is old and the potential of added salt to cause hypertension may cause concern.

Further reading & references

  1. Allen RE, Kirby KA; Nocturnal leg cramps. Am Fam Physician. 2012 Aug 15;86(4):350-5.
  2. Hensley JG; Leg cramps and restless legs syndrome during pregnancy. J Midwifery Womens Health. 2009 May-Jun;54(3):211-8. doi: 10.1016/j.jmwh.2009.01.003.
  3. Leg cramps; NICE CKS, September 2012
  4. Parisi L, Pierelli F, Amabile G, et al; Muscular cramps: proposals for a new classification. Acta Neurol Scand. 2003 Mar;107(3):176-86.
  5. Muscle Cramps, Familial; Online Mendelian Inheritance in Man (OMIM)
  6. Butler JV, Mulkerrin EC, O'Keeffe ST.; Nocturnal leg cramps in older people. (Review); Postgraduate Medical Journal 2002;78:596-598
  7. Ingraham SJ; The role of flexibility in injury prevention and athletic performance: have we stretched the truth? Minn Med. 2003 May;86(5):58-61.
  8. Schwellnus MP, Drew N, Collins M; Muscle cramping in athletes--risk factors, clinical assessment, and management. Clin Sports Med. 2008 Jan;27(1):183-94, ix-x.
  9. Weerapong P, Hume PA, Kolt GS; The mechanisms of massage and effects on performance, muscle recovery and injury prevention. Sports Med. 2005;35(3):235-56.
  10. El-Tawil S, Al Musa T, Valli H, et al; Quinine for muscle cramps. Cochrane Database Syst Rev. 2010 Dec 8;(12):CD005044.
  11. Woodfield R, Goodyear-Smith F, Arroll B; N-of-1 trials of quinine efficacy in skeletal muscle cramps of the leg. Br J Gen Pract. 2005 Mar;55(512):181-5.
  12. Coppin RJ, Wicke DM, Little PS; Managing nocturnal leg cramps--calf-stretching exercises and cessation of quinine treatment: a factorial randomised controlled trial. Br J Gen Pract. 2005 Mar;55(512):186-91.
  13. Guay DR; Are there alternatives to the use of quinine to treat nocturnal leg cramps? Consult Pharm. 2008 Feb;23(2):141-56.
  14. Lynch KE, Feldman HI, Berlin JA, et al; Effects of L-carnitine on dialysis-related hypotension and muscle cramps: a meta-analysis. Am J Kidney Dis. 2008 Nov;52(5):962-71. Epub 2008 Aug 15.
  15. Young GL, Jewell D; Interventions for leg cramps in pregnancy. Cochrane Database Syst Rev. 2002;(1):CD000121.

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Dr Chloe Borton
Current Version:
Peer Reviewer:
Dr John Cox
Document ID:
2015 (v26)
Last Checked:
Next Review:
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