Leg Cramps

Nocturnal leg cramps are sudden, painful, involuntary contractions of the calf or foot muscles, usually at night, lasting seconds to a few minutes and often leaving the muscle tender the next day. They become considerably more common with age and in pregnancy.

In most people they are benign and no cause is ever found. That is a genuine finding rather than an incomplete assessment.

The useful clinical work is distinguishing true cramp from two things that get called cramp and are not: claudication, which is arterial and matters, and restless legs syndrome, which is an urge to move rather than a painful contraction and has quite different treatment.

Common

• Idiopathic nocturnal cramps — the usual answer, particularly over 50
• Medication — diuretics, statins, salbutamol, and anything causing volume depletion. See the list on this page
• Pregnancy, especially the later stages
• Dehydration, and exercise in heat
• Prolonged standing or unaccustomed exertion

Worth checking with a blood test

• Low magnesium, potassium, calcium or sodium
• Kidney disease, particularly in anyone on dialysis
• Underactive thyroid
• Vitamin D deficiency
• Liver disease

Things frequently mistaken for cramp

• Claudication — predictable leg pain on walking a set distance, relieved by standing still. This is arterial disease, not cramp, and it signals cardiovascular risk that needs addressing
• Restless legs syndrome — an uncomfortable urge to move the legs, worse in the evening, relieved by movement. Often associated with low ferritin, which is worth checking and treating
• Spinal stenosis — leg pain on walking that eases on bending forward rather than on standing still
• DVT — constant, with swelling and warmth, rather than a brief spasm
• Peripheral neuropathy

Uncommon

• Motor neurone disease and other neuromuscular conditions — suggested by cramps with progressive weakness, wasting or twitching, rather than by cramps alone

What a consultation covers

• What exactly happens — a painful visible contraction, or an urge to move, or pain on walking? This distinction is most of the diagnosis
• When it occurs — at night, on walking, at rest
• Whether walking brings it on predictably at a certain distance — the claudication question
• Whether it eases on stopping, or on bending forward
• Frequency, and effect on sleep
• Your full medicine list, particularly diuretics and statins
• Fluid intake, alcohol, activity and pregnancy
• Any weakness, wasting or numbness

What we may arrange

Kidney function and electrolytes including magnesium and calcium, thyroid function, vitamin D, liver function, and ferritin where restless legs is likely.

Where the story is claudication, the assessment shifts to cardiovascular risk — blood pressure, cholesterol, HbA1c, smoking — and referral for arterial assessment.

The limits of a video consultation

We cannot feel your foot pulses, which is the key examination in suspected claudication, and we cannot examine your calf for a DVT.

Where the pattern suggests arterial disease or a clot, we will arrange in-person assessment rather than manage it remotely. Both need hands on the leg.

Why do I get cramp at night?

In most people over 50 no cause is ever found, and that is a genuine answer. Nightly calf stretching is the measure with the best evidence, and it is free.

Does magnesium work?

Probably not for most people. Trials in older adults have largely been negative, despite how often it is recommended. It may help in pregnancy. It is harmless to try, but stretching is better supported.

Is it cramp or a blood clot?

Cramp is a brief, intensely painful spasm that passes. A DVT causes constant pain with a swollen, warm, tender calf, usually one-sided. That needs same-day assessment.

Is it cramp or poor circulation?

Claudication comes on predictably after walking a certain distance and settles within minutes of standing still. Cramp does not follow that pattern. Claudication matters, because it signals arterial disease elsewhere too.

What if I feel an urge to move rather than pain?

That is restless legs syndrome, not cramp. It is worth checking ferritin — low iron stores are a common and treatable contributor, even without anaemia.

Could my statin be causing it?

Possibly, though muscle symptoms on statins occur about as often on placebo in blinded trials. That does not make your pain imaginary — it means the statin is often not the cause, and a switch or re-challenge frequently succeeds.

Should I drink tonic water?

No. Quinine is no longer recommended for cramp because of serious blood and cardiac risks, and tonic water is an uncontrolled dose of it.