Legs
Muscle cramps
Sudden, painful, involuntary tightening of a muscle — usually a harmless, short-lived spasm in the calf or foot, but one that must be told apart from a hot, swollen, painful calf, which can signal a clot.
Education and reference only. This explains the common causes of muscle cramps and the warning signs that need urgent help, in plain language — it is not a diagnosis or a substitute for advice from a clinician. If you feel very unwell or are worried, seek medical help.
Quick answer
What is muscle cramps?
A muscle cramp is a sudden, involuntary and often intensely painful tightening of a muscle that you cannot relax, most commonly striking the calf, foot or thigh, frequently at night or during or after exercise. The great majority of cramps are harmless and self-limiting, related to nothing more than overuse, dehydration, prolonged standing or simply ageing muscles.
- Get urgent help: Seek urgent same-day help for a calf that is hot, swollen, tender and painful and stays that way — this can be a deep vein clot (DVT). Call 999 if calf swelling or pain comes with sudden breathlessness, chest pain or coughing up blood — a clot may have travelled to the lungs.
- Self-care: For ordinary cramp, gently stretching and massaging the affected muscle usually breaks the spasm — for a calf cramp, straighten the leg and pull the toes up towards you, then walk it off and rub the muscle.
About muscle cramps
A muscle cramp is a sudden, involuntary and often intensely painful tightening of a muscle that you cannot relax, most commonly striking the calf, foot or thigh, frequently at night or during or after exercise. The great majority of cramps are harmless and self-limiting, related to nothing more than overuse, dehydration, prolonged standing or simply ageing muscles. The important task is to distinguish ordinary cramp from other conditions that can mimic or coexist with it. A calf that becomes hot, swollen, tender and painful — not just cramping briefly but staying sore — can be a deep vein clot, which is urgent. A cramping ache in the calf or thigh that comes on reliably when walking and eases within minutes of stopping suggests poor blood supply to the legs rather than ordinary cramp. Frequent or severe cramps can also relate to thyroid problems, kidney disease or nerve conditions, so persistent or worsening cramps are worth assessing.
When to get help
Call 999 or go to A&E if muscle cramps comes with any of these warning signs:
- Seek urgent same-day help for a calf that is hot, swollen, tender and painful and stays that way — this can be a deep vein clot (DVT).
- Call 999 if calf swelling or pain comes with sudden breathlessness, chest pain or coughing up blood — a clot may have travelled to the lungs.
- See a doctor promptly for a cramping ache in the calf or thigh that reliably comes on when walking and eases with rest — this can mean narrowed leg arteries.
- See a doctor for frequent, severe or worsening cramps, or cramps that disturb sleep most nights.
- Seek help for cramps with muscle weakness, numbness, or changes in the colour or temperature of the foot or leg.
When to see a doctor
Occasional cramp that eases with stretching and has an obvious trigger such as exercise needs no medical attention. Seek urgent same-day help for any calf that becomes and stays hot, swollen, tender and painful, as a deep vein clot must be excluded, and call 999 if breathlessness, chest pain or coughing up blood develops. See a doctor for a cramping leg ache that reliably comes on with walking and stops at rest, which can signal poor circulation, and for cramps that are frequent, severe, worsening, disturb your sleep, or come with weakness, numbness or changes in the foot, so that an underlying cause can be looked for.
Not sure how urgent it is? It is always OK to call NHS 111 for advice, day or night.
What can cause it
Common causes of muscle cramps
Muscle cramps has many possible causes. Each links to a full, plain-language guide to that condition — what it is, how it's treated and when to seek help.
What helps
Self-care and what you can do
For ordinary cramp, gently stretching and massaging the affected muscle usually breaks the spasm — for a calf cramp, straighten the leg and pull the toes up towards you, then walk it off and rub the muscle. To reduce how often cramps strike, stay well hydrated, especially around exercise, stretch your calves before bed if you get night cramps, and avoid sudden increases in activity. Wearing supportive footwear and gently keeping active help keep muscles supple. Note when your cramps happen and what brings them on, as this helps your clinician if they become a problem. Stop and seek help, however, for any calf that stays hot, swollen, tender and painful, or for cramping leg pain that reliably comes on with walking.
Answers
Muscle cramps: frequently asked questions
What causes ordinary muscle cramps?
Most cramps are harmless and relate to overuse, prolonged standing, dehydration or ageing muscles, and often strike the calf or foot at night or around exercise. They ease with gentle stretching and usually need no treatment.
How do I tell cramp from a blood clot?
Ordinary cramp is a brief, painful spasm that settles quickly. A clot (DVT) causes a calf that stays hot, swollen, tender and painful rather than easing. A persistently sore, swollen calf needs urgent same-day assessment.
Why do I get cramp in my calf when I walk?
A cramping calf or thigh ache that reliably comes on when walking and eases within minutes of stopping can be a sign of narrowed leg arteries reducing blood flow. This should be assessed by a doctor rather than dismissed as simple cramp.
Can drinking more water stop cramps?
Staying well hydrated, especially around exercise, can reduce cramps for some people, along with stretching and keeping active. But frequent, severe or worsening cramps, or a persistently sore swollen calf, should still be checked.
Sources
Where this is drawn from
- NICE CKS: Leg cramps.
- Circulation Foundation: peripheral arterial disease.
Related symptoms
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