Leg Cramps at Night: Causes, What Actually Helps, and What Doesn't

A cramp is a sudden, involuntary and painful tightening of a muscle, most often the calf, sometimes the foot or thigh. At night it often strikes while lying with the toes pointed. Most night cramps have no serious cause — they become more common with age, inactivity and long periods of standing or sitting — but a few medicines and medical conditions make them more likely.

How do you stop a leg cramp right now?

• Straighten the leg and pull your toes up towards your knee, or stand up and put weight on the cramped leg with the heel down.
• Massage the muscle firmly.
• Walk around for a minute once the worst has passed.
• Warmth afterwards, such as a hot water bottle, can ease the lingering soreness.

How can I prevent leg cramps at night?

Stretch before bed. In a randomised trial published in the Journal of Physiotherapy in 2012, 80 adults over 55 with night cramps either stretched their calves and hamstrings every night just before sleep for six weeks or did no specific stretching. The stretching group had 1.2 fewer cramps per night than the control group and their cramps were less painful (1.3 cm less on a 10 cm pain scale). It costs nothing and takes three minutes.

During the day, regular walking and calf raises keep the muscles conditioned. At night, a pillow under the feet or loose bedclothes that don't push the toes downwards can help. If you train, cool down properly after hard leg sessions.

Does magnesium help leg cramps?

Probably not for most people. A 2020 Cochrane review of 11 trials concluded that magnesium supplements are unlikely to provide meaningful cramp prevention for older adults with ordinary leg cramps; evidence in other groups was conflicting or missing. Our magnesium guide explains who might benefit from magnesium for other reasons. Bananas for potassium are a popular remedy with no trial evidence for cramps.

What about quinine?

Quinine does reduce cramps a little: a 2015 Cochrane review of 23 trials found it cut cramp numbers by 28 percent, intensity by 10 percent and cramp days by 20 percent over two weeks compared with placebo. But it can cause rare, serious side effects, including dangerous blood disorders and heart rhythm problems, so regulators such as the US FDA advise against using it routinely for leg cramps. Do not take quinine without a doctor's advice, and never in larger doses than prescribed.

Can medicines cause leg cramps?

Yes. A 2012 study of prescription data for 4.2 million people in British Columbia, Canada, looked at whether cramp treatment started more often after people aged 50 and over began certain drugs. It did: 2.4 times more often after inhaled long-acting beta-agonists for asthma or COPD, 2.1 times after potassium-sparing diuretics and 1.5 times after thiazide-type diuretics ('water tablets' for blood pressure); the link with statins was small. If cramps started after a new medicine, tell your doctor — do not stop it on your own.

Why do muscles cramp during exercise?

Mostly from fatigue and intensity, not dehydration. A study of 210 Ironman triathletes found no differences in body-weight change or blood salt levels between those who cramped and those who didn't; the risk factors were racing faster and a history of cramps. Still, in Pakistani heat, drinking and replacing salt during long sessions is sensible — see our hydration guide. Pickle brine has an interesting effect: in a 2010 study, about 75 ml of pickle juice ended electrically induced cramps 49 seconds faster than water (85 vs 134 seconds), too quickly to be from salt absorption, which suggests a reflex triggered in the mouth and throat.

When are leg cramps a sign of something serious?

• A calf that stays swollen, red, warm or tender after the cramp — this can be a blood clot (DVT); seek urgent care.
• Cramps with muscle weakness, wasting, twitching or numbness.
• Cramps that are frequent and severe, or spreading to many muscles, including the hands.
• Cramps with symptoms of diabetes, thyroid problems, kidney or liver disease.
• Leg pain that comes on with walking and eases with rest — this can be poor circulation, not cramp.

This article is general information, not medical advice. See a doctor about cramps that are frequent, severe or disturb your sleep, and seek urgent care for a swollen, red or warm calf.