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Supplements for Leg Cramps: Magnesium, Vitamin K2, Quinine Warnings and What Helps at Night

No supplement reliably stops night leg cramps. In older adults, magnesium is unlikely to help (grade B, Cochrane review). One vitamin K2 trial in adults 65 and older reported fewer cramps, but it was retracted and replaced (grade D), and nightly calf and hamstring stretching helped in another (grade C). Quinine reduces cramps a little, but it can cause dangerous blood and kidney reactions. A swollen, painful calf on one side needs urgent care.

Published How we grade evidenceEditorial policy

Night leg cramps are sudden, painful tightening of the calf or foot muscles at rest or in sleep, and they are common in older adults (Kuusipalo 2026). This guide covers adults; exercise and pregnancy cramps have their own sections.

The short version

  • Magnesium made no meaningful difference for night cramps in older adults. Grade B (Garrison 2020).
  • Vitamin K2 reported fewer cramps in one 8-week trial of 199 adults aged 65 and older, but the journal retracted and replaced it in 2025, and its reported confidence interval does not match its own data. Grade D (Tan, replaced 2025).
  • Stretching calves and hamstrings before bed helped in one trial; calf stretching alone did not in another. Grade C (Hallegraeff 2012; Coppin 2005).
  • Quinine cut cramps by about a quarter, but it has caused kidney failure and deaths. Grade B for a small benefit (El-Tawil 2015; Page 2017).
OptionWhat trials foundSize of effectGrade
MagnesiumNo clear difference in older adults0.18 fewer cramps a weekB
Vitamin K2Fewer cramps in one trial, retracted and replaced in 20250.96 vs 3.63 cramps a weekD
Stretching before bedFewer, milder cramps in one trial1.2 fewer a nightC
Vitamin B complexFewer cramps; 14 of 28 people took it86% much betterC
Vitamin ENo clear differenceNoneC
Quinine (medicine)A small benefit, serious harms; not FDA-approved for cramps28% fewer crampsB (skip)

Does magnesium help leg cramps?

Grade B: probably not, for ordinary night cramps in older adults. A 2020 Cochrane review found 11 trials (735 people). In idiopathic cramps (no known cause), mostly in adults with an average age in their 60s, magnesium changed cramps by just 0.18 a week against placebo (5 trials, 307 people), and the share of people whose cramps fell by a quarter was no different, at high certainty. Stomach side effects such as diarrhea affected 11% to 37% of people on magnesium, against 10% to 14% on placebo (Garrison 2020). In 94 adults, cramps fell on both magnesium oxide and placebo, with no difference between them (Roguin Maor 2017).

Newer trials split. In 175 adults in Ukraine, 226 mg of magnesium oxide monohydrate at bedtime for 60 days cut cramp episodes by 3.4 against 2.6 on placebo (Barna 2021). In 121 adults in Finland, magnesium did no better than placebo, while knee-high compression stockings reduced weekly cramps by 1.43 (Kuusipalo 2026).

Which magnesium is best? Trials used magnesium oxide and other salts; we found no trial comparing forms for cramps. Upper limit for adults: 350 mg of magnesium a day from supplements, because more can cause diarrhea; take more only with blood tests or your clinician's advice (NIH ODS; check your stack). With kidney disease, magnesium can build up, so ask first. See our magnesium page.

Does vitamin K2 help leg cramps?

Grade D: one trial, retracted and replaced. In China, 199 adults aged 65 and older with at least 2 night cramps in 2 weeks of screening took 180 mcg of vitamin K2 (menaquinone-7) or placebo daily for 8 weeks. Weekly cramps fell from 2.60 to 0.96 on K2 and rose from 2.71 to 3.63 on placebo, and cramps were also shorter and milder; no side effects were tied to K2 (Tan, replaced 2025). The journal retracted the original 2024 article and published a corrected replacement in 2025 (notice); we cite and quote the 2025 replacement, which is the version PubMed now lists, not the retracted original. Even so, its reported confidence interval does not match its own data: the standard deviations and group sizes it reports imply a much wider range, so we grade it D. A small crossover trial in 39 people on dialysis also found fewer cramps (Xu 2022). One trial in older adults is not enough to call it settled.

If you take warfarin, don't start vitamin K without your prescriber, because vitamin K can weaken it (NIH ODS). See our vitamin K2 page.

Should you take quinine for leg cramps?

Grade B for a small benefit, but we'd skip it. Quinine is a prescription malaria drug, not a supplement. Across 20 placebo-controlled trials (1,140 people), it cut cramp numbers by 28%, intensity by 10% and cramp days by 20% over 2 weeks, on low to moderate quality evidence (El-Tawil 2015).

The harms are rare but severe. In an Oklahoma registry, 19 people developed quinine-induced clotting in small blood vessels (thrombotic microangiopathy) with kidney injury; 17 of the 18 who survived to treatment needed dialysis, and 8 died (Page 2017). The FDA received reports of dangerously low platelets in 64 people, 55 of them hospitalized (Brinker 2002). The FDA has not approved quinine for leg cramps, and the approved US label carries a boxed warning that using quinine for night leg cramps can cause life-threatening blood reactions, and that this risk outweighs any potential benefit (FDA label). The American Academy of Neurology advises against routine use (Katzberg 2010).

Tonic water is not a treatment: US rules cap its quinine at 83 parts per million (21 CFR 172.575), and one of the 19 registry cases followed tonic water (Page 2017).

Does stretching help night leg cramps?

Grade C, mixed. In 80 adults over 55, stretching the calves and hamstrings every night before sleep for 6 weeks cut cramps by 1.2 a night and pain by 1.3 cm on a 10 cm scale against no stretching (Hallegraeff 2012). In 191 people on quinine, advice to do calf stretches alone made no difference over 12 weeks (Coppin 2005). Cochrane rated the stretching evidence low to very low certainty (Hawke 2021). Stretching costs nothing, so it is a reasonable first try.

Do B vitamins, vitamin E or vitamin D help?

  • Vitamin B complex: grade C. Among 28 older people with hypertension and severe night cramps, a B complex capsule taken three times a day for 3 months brought clear relief in 86% of those on it, while placebo brought no change (Chan 1998). Each capsule held 30 mg of a vitamin B6 form, so 90 mg a day. Upper limit for adults: 100 mg of vitamin B6 a day, because more can cause nerve damage; take more only with blood tests or your clinician's advice (NIH ODS; check your stack). A neurology review rated B complex "possibly effective" on this one trial (Katzberg 2010).
  • Vitamin E: grade C, no clear difference. In a crossover trial of 27 male veterans, vitamin E did not reduce cramps, while quinine did (Connolly 1992). See our vitamin E page.
  • Vitamin D: grade C, no clear difference. In a reanalysis of a trial in 230 postmenopausal women with low vitamin D, raising their levels did not change cramps (Weiker 2017). See our vitamin D page.

Does CoQ10 help leg cramps?

We found no trial of CoQ10 for ordinary night cramps. Grade C, mixed, for muscle symptoms in statin users: pooling 12 trials (575 people) found less muscle pain and cramping (Qu 2018), a 2020 pooling of 7 trials (321 people) found no benefit for muscle pain (Kennedy 2020), and a 2025 pooling of 7 trials (389 people) found a small drop in pain (Kovacic 2025). See our CoQ10 page.

Do electrolytes or pickle juice help cramps?

These are mostly about exercise cramps. Grade C. In 13 college men exercising in heat, 69% still cramped while drinking an electrolyte sports drink, though in the 7 who cramped both times it came later (36.8 against 14.6 minutes) (Jung 2005). Pooling 9 studies (11,274 people), hydration was not consistently linked to exercise cramps; a history of cramps was the clearest predictor (Costa 2026). See our electrolytes page.

Pickle juice: grade C. In dehydrated men, cramps set off by an electrical stimulus lasted 49 seconds less after pickle juice than after water, with no change in blood salts, which suggests a reflex (Miller 2010). In 74 people with cirrhosis, sips at cramp onset eased cramp severity more than tap water (Tapper 2022). It is very salty; skip it if you have been told to limit salt.

What about leg cramps in pregnancy?

Grade C, uncertain. A 2020 Cochrane review of 8 small trials (576 women) could not pool results; magnesium findings were inconsistent, calcium very low certainty, and vitamin D showed little or no effect (Luo 2020). Pooled analyses disagree: 4 trials (332 women) found no drop in cramps (Liu 2021), while another pooling of 4 trials (about 364 women) found a benefit (Patil 2026). Take any supplement in pregnancy only as advised by your midwife or obstetric team. See our prenatal supplements guide.

Can medicines cause leg cramps?

Some may, though the evidence is observational. In British Columbia health records (4.2 million residents), adults 50 and older started quinine for cramps more often in the year after starting inhaled long-acting beta-agonists, used for asthma and COPD (2.4 times), potassium-sparing water pills (2.1 times) or thiazide-like water pills (1.5 times); links with statins and loop water pills were small (Garrison 2012). If cramps began after a new medicine, ask the prescriber. Don't stop a prescribed medicine on your own.

Restless legs is different: an urge to move the legs at rest rather than a hard, painful muscle. Iron eased it in a Cochrane review (Trotti 2019), and a 2025 sleep medicine guideline says to test iron stores (ferritin) before deciding on iron (Winkelman 2025). See our restless legs protocol.

What we'd skip

  • Quinine pills or tonic water: a small benefit against kidney failure, blood reactions and deaths (Page 2017; FDA label).
  • Magnesium for ordinary night cramps in older adults: no meaningful benefit in pooled trials (Garrison 2020).
  • Vitamin E or vitamin D for cramps: no effect in trials (Connolly 1992; Weiker 2017).
  • Potassium or calcium pills outside pregnancy: a 2026 review found no supporting evidence (Patil 2026), and extra potassium is dangerous with kidney disease (NIH ODS).

Safety and interactions

When to see a doctor

  • Urgent: one calf that is swollen, warm, red or tender: a possible blood clot.
  • Same day: dark urine after muscle pain, especially on a statin; cramps with weakness, numbness or shrinking muscles; or bruising, bleeding or little urine on quinine (Page 2017).
  • Soon: frequent, severe cramps; cramps after a new medicine; or cramps on water pills, which can lower potassium and magnesium.
  • Children: ask a clinician.

Don't stop a prescribed medicine on your own; ask the prescriber or pharmacist. If you are pregnant or breastfeeding, ask your midwife or obstetric team.

FAQ

What supplement helps with leg cramps at night? None reliably. One vitamin K2 trial in adults 65 and older reported fewer cramps, but the journal retracted and replaced it in 2025 (grade D), while magnesium is unlikely to help older adults (grade B). Nightly calf and hamstring stretching helped in one trial (grade C).

Which magnesium is best for leg cramps? We found no trial comparing forms. A Cochrane review found magnesium unlikely to help night cramps in older adults (grade B), and the adult upper limit from supplements is 350 mg a day.

Does pickle juice help cramps? It shortened cramps set off in a lab in dehydrated men and eased cramp severity in people with cirrhosis (grade C). It is very salty.

Is tonic water good for leg cramps? No. It is not a treatment, and quinine itself has caused kidney failure and deaths; one serious reaction in a US registry of 19 cases followed tonic water.

Sources

  1. Kuusipalo A, et al. Secondary prevention of leg cramps using compression stockings or magnesium supplements: a three-arm randomized clinical trial. Trials. 2026. PubMed 41680812 · doi:10.1186/s13063-025-09370-z
  2. Garrison SR, et al. Magnesium for skeletal muscle cramps. Cochrane Database Syst Rev. 2020. PubMed 32956536 · doi:10.1002/14651858.CD009402.pub3
  3. Tan J, et al. Vitamin K2 in Managing Nocturnal Leg Cramps: A Randomized Clinical Trial. JAMA Intern Med. 2024 (retracted and replaced 2025; the replacement version). PubMed 39466236 · doi:10.1001/jamainternmed.2024.5726
  4. Hallegraeff JM, et al. Stretching before sleep reduces the frequency and severity of nocturnal leg cramps in older adults: a randomised trial. J Physiother. 2012. PubMed 22341378 · doi:10.1016/S1836-9553(12)70068-1
  5. Coppin RJ, et al. Managing nocturnal leg cramps--calf-stretching exercises and cessation of quinine treatment: a factorial randomised controlled trial. Br J Gen Pract. 2005. PubMed 15808033
  6. El-Tawil S, et al. Quinine for muscle cramps. Cochrane Database Syst Rev. 2015. PubMed 25842375 · doi:10.1002/14651858.CD005044.pub3
  7. Page EE, et al. Quinine-Induced Thrombotic Microangiopathy: A Report of 19 Patients. Am J Kidney Dis. 2017. PubMed 28780041 · doi:10.1053/j.ajkd.2017.05.023
  8. Roguin Maor N, et al. Effect of Magnesium Oxide Supplementation on Nocturnal Leg Cramps: A Randomized Clinical Trial. JAMA Intern Med. 2017. PubMed 28241153 · doi:10.1001/jamainternmed.2016.9261
  9. Barna O, et al. A randomized, double-blind, placebo-controlled, multicenter study assessing the efficacy of magnesium oxide monohydrate in the treatment of nocturnal leg cramps. Nutr J. 2021. PubMed 34719399 · doi:10.1186/s12937-021-00747-9
  10. Tan J, et al. Notice of Retraction and Replacement. Tan and Zhu. Vitamin K2 in Managing Nocturnal Leg Cramps: A Randomized Clinical Trial. JAMA Intern Med. 2024;184(12):1443-1447. JAMA Intern Med. 2025. PubMed 40314950 · doi:10.1001/jamainternmed.2025.2160
  11. Xu D, et al. Vitamin K2 as a potential therapeutic candidate for the prevention of muscle cramps in hemodialysis patients: A prospective multicenter, randomized, controlled, crossover pilot trial. Nutrition. 2022. PubMed 35203045 · doi:10.1016/j.nut.2022.111608
  12. Brinker AD, et al. Spontaneous reports of thrombocytopenia in association with quinine: clinical attributes and timing related to regulatory action. Am J Hematol. 2002. PubMed 12210813 · doi:10.1002/ajh.10148
  13. Katzberg HD, et al. Assessment: symptomatic treatment for muscle cramps (an evidence-based review): report of the therapeutics and technology assessment subcommittee of the American academy of neurology. Neurology. 2010. PubMed 20177124 · doi:10.1212/WNL.0b013e3181d0ccca
  14. Hawke F, et al. Non-drug therapies for the secondary prevention of lower limb muscle cramps. Cochrane Database Syst Rev. 2021. PubMed 33998664 · doi:10.1002/14651858.CD008496.pub3
  15. Chan P, et al. Randomized, double-blind, placebo-controlled study of the safety and efficacy of vitamin B complex in the treatment of nocturnal leg cramps in elderly patients with hypertension. J Clin Pharmacol. 1998. PubMed 11301568
  16. Connolly PS, et al. Treatment of nocturnal leg cramps. A crossover trial of quinine vs vitamin E. Arch Intern Med. 1992. PubMed 1520054
  17. Weiker MK, et al. Muscle Cramps Do Not Improve With Correction of Vitamin D Insufficiency. WMJ. 2017. PubMed 29357208
  18. Qu H, et al. Effects of Coenzyme Q10 on Statin-Induced Myopathy: An Updated Meta-Analysis of Randomized Controlled Trials. J Am Heart Assoc. 2018. PubMed 30371340 · doi:10.1161/JAHA.118.009835
  19. Kennedy C, et al. Effect of Coenzyme Q10 on statin-associated myalgia and adherence to statin therapy: A systematic review and meta-analysis. Atherosclerosis. 2020. PubMed 32179207 · doi:10.1016/j.atherosclerosis.2020.03.006
  20. Kovacic S, et al. Effects of coenzyme Q10 supplementation on myopathy in statin-treated patients: a systematic review and meta-analysis. J Nutr Sci. 2025. PubMed 41158831 · doi:10.1017/jns.2025.10043
  21. Jung AP, et al. Influence of Hydration and Electrolyte Supplementation on Incidence and Time to Onset of Exercise-Associated Muscle Cramps. J Athl Train. 2005. PubMed 15970952
  22. Costa LDS, et al. Risk Factors for Exercise-Associated Muscle Cramps: A Systematic Review With Meta-Analysis. Muscle Nerve. 2026. PubMed 42693659 · doi:10.1002/mus.70389
  23. Miller KC, et al. Reflex inhibition of electrically induced muscle cramps in hypohydrated humans. Med Sci Sports Exerc. 2010. PubMed 19997012 · doi:10.1249/MSS.0b013e3181c0647e
  24. Tapper EB, et al. Pickle Juice Intervention for Cirrhotic Cramps Reduction: The PICCLES Randomized Controlled Trial. Am J Gastroenterol. 2022. PubMed 35416793 · doi:10.14309/ajg.0000000000001781
  25. Luo L, et al. Interventions for leg cramps in pregnancy. Cochrane Database Syst Rev. 2020. PubMed 33275278 · doi:10.1002/14651858.CD010655.pub3
  26. Liu J, et al. Effect of oral magnesium supplementation for relieving leg cramps during pregnancy: A meta-analysis of randomized controlled trials. Taiwan J Obstet Gynecol. 2021. PubMed 34247796 · doi:10.1016/j.tjog.2021.05.006
  27. Patil S, et al. The Role of Electrolytes in Muscle Pain Syndromes: A Systematic Review and Meta-Analysis With Implications for Temporomandibular Disorder. Int Dent J. 2026. PubMed 41812583 · doi:10.1016/j.identj.2026.109488
  28. Garrison SR, et al. Nocturnal leg cramps and prescription use that precedes them: a sequence symmetry analysis. Arch Intern Med. 2012. PubMed 22157068 · doi:10.1001/archinternmed.2011.1029
  29. Trotti LM, et al. Iron for the treatment of restless legs syndrome. Cochrane Database Syst Rev. 2019. PubMed 30609006 · doi:10.1002/14651858.CD007834.pub3
  30. Winkelman JW, et al. Treatment of restless legs syndrome and periodic limb movement disorder: an American Academy of Sleep Medicine clinical practice guideline. J Clin Sleep Med. 2025. PubMed 39324694 · doi:10.5664/jcsm.11390