GPAtlas🧭 When to suspect
A leg cramp is a sudden, involuntary, painful contraction of a muscle, most often the calf, but also the foot or thigh.
• Episodes typically last from seconds to ten minutes and leave the muscle visibly hard and tender.
• Episodes may be followed by residual soreness for up to 24 hours.
• Cramps are very common and occur predominantly at night or at rest.
• Prevalence rises sharply with age – more than a third of people over 60 are affected.
The two clinical tasks in primary care are:
• First, confirm that this is a true cramp: a palpable, painful contraction relieved by stretching.
• A true cramp is not the urge-to-move of restless legs syndrome, the exertional pain of claudication, or a neuropathic dysaesthesia.
• Then separate idiopathic (primary) cramps – benign and the large majority – from secondary cramps driven by a drug or an underlying condition.
A focused search for a secondary cause, and exclusion of dangerous mimics such as deep vein thrombosis (DVT), peripheral arterial disease (PAD) and cellulitis, does most of the diagnostic work.
| Common drug causes | Common medical (secondary) causes |
|---|---|
|
• Diuretics (loop and thiazide) – via electrolyte and fluid loss • Statins – more often myalgia than true cramp • Beta-agonists (e.g. salbutamol) • Nifedipine and other calcium-channel blockers • Raloxifene and nicotinic acid |
• Pregnancy – around a third in the third trimester • Peripheral arterial disease and chronic venous disease • Chronic kidney disease or haemodialysis (cramps in ~50% with uraemia) and liver cirrhosis • Hypothyroidism (cramps in 20–50%) and diabetic peripheral neuropathy • Electrolyte disturbance (low sodium, calcium, magnesium or potassium); dehydration or salt depletion after heavy or hot-weather exertion • Motor neurone disease (MND) and other neuromuscular disorders |
|
🧠 Clinical pearl • The commonest misdiagnosis is restless legs syndrome mislabelled as cramp – and it leads to inappropriate quinine. • Restless legs is an urge to move with an unpleasant crawling sensation that is worse at rest and relieved by movement, with no painful contraction. • A true cramp is the opposite: a visible, palpable, painful spasm relieved by stretching the muscle. |
Source: NICE
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