Leg cramps
Exam Tips
- Differentiate cramp from restless legs syndrome: cramp is painful with palpable muscle tightening; RLS is an urge to move with unpleasant sensations but no hard contracted muscle.
- Classic idiopathic pattern is brief (<10 min), nocturnal, unilateral calf pain relieved by stretching, with normal examination between episodes.
- Duration >10 minutes, daytime frequent cramps, widespread cramps, or objective neurological signs suggest secondary pathology and should trigger targeted investigations.
- In OSCE stations, demonstrate acute relief manoeuvre for calf cramp (knee extension + ankle dorsiflexion) and provide safety-net advice.
- Mention quinine cautiously: not routine first-line in UK practice because benefit is modest and adverse effects can be serious.
Definition
Leg cramps are sudden, involuntary, painful contractions of a leg muscle, most often the calf, with episodes usually lasting seconds to a few minutes and then resolving spontaneously. In clinical practice they are commonly nocturnal and idiopathic, although persistent, atypical, or daytime symptoms should prompt assessment for neurological, vascular, metabolic, endocrine, pregnancy-related, or drug-induced causes.
Pathophysiology
The exact mechanism of idiopathic nocturnal leg cramps is uncertain, but current understanding supports peripheral motor nerve hyperexcitability causing repetitive high-frequency discharge of motor units, leading to sustained painful contraction (often in gastrocnemius/soleus). Night-time plantar-flexed posture, muscle fatigue/shortening, and age-related neuromuscular changes may lower cramp threshold. Secondary cramps occur when systemic disease (for example renal failure, thyroid disease, diabetes), electrolyte disturbance (for example low magnesium/calcium or sodium/potassium abnormalities), neurogenic disease, vascular insufficiency, pregnancy, or medicines increase neuromuscular irritability or impair muscle perfusion.
Risk Factors
- Older age (prevalence rises in people over 60 years)
- Pregnancy
- Strenuous or unaccustomed exercise
- Peripheral arterial disease or chronic venous insufficiency
- Neurological disease (for example peripheral neuropathy, lumbar canal stenosis, Parkinson disease, motor neurone disease, multiple sclerosis, stroke)
- Metabolic/endocrine disease (for example diabetes, thyroid disease, Addison disease, cirrhosis, end-stage renal disease/haemodialysis)
- Electrolyte disturbance (hypomagnesaemia, hypocalcaemia, hyponatraemia, hypo- or hyperkalaemia)
- Vitamin B or D deficiency
- Medicines: long-acting beta-2 agonists, thiazide or potassium-sparing diuretics, statins, nifedipine, imatinib, conjugated oestrogens, naproxen, penicillamine, raloxifene, teriparatide
Clinical Features
Symptoms
- Sudden intense pain in calf (sometimes foot, less often thigh), commonly at night or at rest
- Episode duration typically seconds to less than 10 minutes
- Residual local muscle tenderness for hours after the spasm
- Sleep disruption and daytime tiredness
- Usually unilateral and affecting a single muscle group
Signs
- Visible or palpable hardening/knotting of the affected muscle during attack
- Abnormal foot/ankle posture during cramp (often plantar flexion)
- Relief with passive or active stretching (for calf cramp, knee extension plus ankle dorsiflexion)
- Normal examination between episodes in idiopathic cases
- Red flags for secondary causes: neurological deficit, fasciculations/wasting, abnormal reflexes, reduced pulses, calf swelling/varicosities
Investigations
Management
Lifestyle Modifications
- Reassure: idiopathic nocturnal cramps are common and often benign; safety-net for change in frequency, severity, duration, or pattern
- During an attack: immediate stretching and massage (calf cramp: straighten knee and dorsiflex ankle); symptoms usually self-limit
- Trial preventive stretching (calf plus hamstring) up to three times daily if helpful; evidence is limited but low-risk
- Sleep positioning strategies: avoid prolonged plantar-flexed posture, keep bedding loose, consider foot support to reduce toe-pointing
- Review and address reversible triggers (dehydration, overexertion, medication contributors, alcohol excess)
- See Figure: gastrocnemius-soleus dorsiflexion stretch technique in a clinical skills atlas for exam demonstration
Pharmacological Treatment
Simple analgesia for post-cramp tenderness
- Paracetamol 1 g orally every 4-6 hours when required (maximum 4 g/day)
- Ibuprofen 200-400 mg orally up to three times daily with food (use lowest effective dose for shortest duration)
Useful after the episode rather than during brief cramps. Avoid/limit NSAIDs in CKD, peptic ulcer disease, heart failure, anticoagulant use, or high GI/CV risk; check age/comorbidity and concomitant medicines.
Quinine salts (not routine; specialist/exceptional use only)
- Quinine sulfate 200-300 mg at night (short trial only, typically up to 4 weeks, then stop if no clear benefit)
Not first-line due to limited benefit and important harms. Safety warnings: thrombocytopenia, arrhythmia/QT prolongation, cinchonism (tinnitus, hearing/visual disturbance), hypoglycaemia, severe hypersensitivity, and major drug interactions. Avoid in prolonged QT, myasthenia gravis, optic neuritis, and use caution in pregnancy and renal/hepatic impairment.
Complications
- Sleep disturbance with daytime somnolence
- Reduced quality of life and distress from recurrent pain
- Persistent post-cramp muscle tenderness
- Rare severe complication: muscle/tendon-related vascular avulsion injury
Prognosis
Most idiopathic nocturnal leg cramps are benign, intermittent, and may improve spontaneously, but recurrence is common in older adults. Prognosis depends on identifying and treating secondary causes where present; persistent atypical symptoms warrant reassessment to exclude neurological, vascular, or systemic disease.
Sources & References
🏥BMJ Best Practice(1)
💊BNF Drug References(1)
- Quinine[management.pharmacological]
✅NICE Guidelines(1)
- Leg cramps[overview]
📖Textbook References(1)
- [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 79, 80)[context]