Does vitamin B12 help with restless legs and muscle cramps?

For restless legs, nobody knows, because it has not been tested. A 2025 meta-analysis says plainly that there are no controlled trials of vitamin B12 as a treatment for restless legs. The same review pooled 21 studies of 1298 people with restless legs and 3629 without, and their blood B12 was no different, a mean gap of 10.08 pg/mL with a confidence interval from 46.85 lower to 26.69 higher. For leg cramps there are two small trials of B vitamins, in older adults with high blood pressure and in pregnant women. In the first, B12 was one of four vitamins in the capsule. The second does not say which B vitamins were given. Neither can tell you what B12 alone does.

Unsettled. Whether B12 helps restless legs is an open question, not a tested one. The idea comes from observational studies, and the largest synthesis of them found no difference in B12 levels at all. A supplement that has never been trialled for a condition cannot be called a treatment for it.

What the trials found

Restless legs

A 2024 systematic review gathered every randomized trial of a supplement for restless legs it could find: 10 trials in 482 people. Magnesium, vitamin B6, iron, vitamins C, D and E and valerian had all been tried. Vitamin B12 had not. The 2025 meta-analysis reached the same blank from a different direction, and its authors wrote that no controlled trial of B12 treatment exists.

The case for a link rests on observational studies. In a retrospective study at one hospital, 80 people with restless legs had lower B12 than 80 matched controls, and each 1 pg/mL more B12 went with slightly lower odds of the condition, an odds ratio of 0.97 with an interval from 0.96 to 0.98. In a cross-sectional study of 146 children and teenagers aged 10 to 16, those with restless legs had lower B12, and the authors say the design cannot show cause. Both are associations from single sites. The 2025 meta-analysis, pooling 21 studies, found no difference in B12 at all.

Muscle cramps

In a 1998 double-blind trial, 28 older adults with high blood pressure and severe night leg cramps took a capsule of four B vitamins, B12 among them, or a placebo three times a day. After 3 months, 86 percent of those on the vitamins had a marked remission of cramps, and the placebo group had no significant change from where they started. That is 14 people per group in a trial from Taiwan, with a mixture of vitamins, so B12's own share cannot be separated.

A Cochrane review of leg cramps in pregnancy found one small trial of oral vitamin B in 42 women. It did not report how often cramps happened on their own, only a combined score of how often and how badly, and on that score the risk ratio was 0.29, interval 0.11 to 0.73. The reviewers rated it low certainty, and the abstract does not say which B vitamins were used.

Who should be careful

Not for everyone. People on two kinds of medicine have a real reason to have B12 checked, whatever their legs are doing. The NIH Office of Dietary Supplements says stomach acid blockers and metformin can lower vitamin B12 levels. If you take either regularly, ask about a blood test rather than guessing.

B12 itself is a low-risk supplement. The Food and Nutrition Board set no upper limit for it because of its low potential for toxicity. That makes a bottle unlikely to hurt you. It does not make it likely to help your legs. The sleep medicine guideline asks for iron tests in everyone with significant restless legs, and a bottle of B12 is no substitute for them. Numbness, burning or pins and needles in the feet are a different complaint from the urge to move, and they deserve their own visit to a doctor rather than a guess about restless legs.

What expert bodies say

The 2025 guideline of the American Academy of Sleep Medicine says that everyone with clinically significant restless legs should have iron studies, including ferritin and transferrin saturation, tested regularly. The guideline makes no recommendation about vitamin B12. The NIH fact sheet on B12 covers its deficiency and its interactions with medicines and does not list restless legs or cramps as uses.

How we searched

What would change this answer

• A placebo-controlled randomized trial of B12 in people with restless legs whose B12 is low or borderline, scored on the standard restless legs severity scale. This trial has not been run.
• A trial of B12 on its own for night leg cramps. One existing trial gave four B vitamins at once, and the other does not say which it gave.
• The full Cochrane text, to learn which vitamin B the pregnant women took.

For what B12 does, who runs short and how to get it from food, see the vitamin B12 guide. For the nutrient with the strongest evidence in restless legs, see iron and restless legs, and for cramps, magnesium and leg cramps.

Sources

1. ev-b12rls-01 · Observational data · systematic review and meta-analysis of observational (case-control and cross-sectional) studies · n = 21 studies, 1298 patients, 3629 controls
   Twenty-one studies, including 1298 patients with RLS and 3629 controls, examined vitamin B12 levels and showed no statistical difference in vitamin B12 levels between patients with RLS and controls (MD = -10.08; 95% CI = -46.85 to 26.69, P = 0.59; heterogeneity, I2 = 89%; P < 0.00001)
   
   Who: patients with primary or secondary restless legs syndrome and controls
   Effect: serum B12 MD -10.08 pg/mL (95% CI -46.85 to 26.69), P = 0.59, I2 89%
   Certainty: Synthesis of observational comparisons of levels, not treatment; high heterogeneity. Synthesis of observational studies: level C.
   PLoS One, 2025 · checked 2026-10-07 · we read the fulltext
2. ev-b12rls-02 · Meta-analysis or systematic review · systematic review and meta-analysis · n = no controlled trial of vitamin B12
   The results showed that vitamin B1 (P = 0.362) or B12 (P = 0.59) levels in RLS patients were not statistically different from those in the control group, and there were no controlled trials of vitamin B1 and B12 treatment for RLS
   
   Who: randomized trials of vitamin treatment for restless legs syndrome
   Effect: no controlled trial of vitamin B12 treatment for RLS
   Certainty: Knowledge boundary: the answer to "does B12 help with RLS" was not checked.
   PLoS One, 2025 · checked 2026-10-07 · we read the fulltext
3. ev-b12rls-03 · Meta-analysis or systematic review · systematic review of randomized controlled trials · n = 10 RCTs, 482
   A total of 10 randomized clinical trials involving 482 participants were analyzed, focusing on the impact of various supplements on symptom severity, sleep quality, and daytime sleepiness.
   
   Who: patients with restless legs syndrome in randomized trials of dietary supplements
   Effect: no vitamin B12 trial among the 10 (full text searched for B12 and cobalamin)
   Certainty: The PMC full text was checked by searching for B12/cobalamin: zero mentions.
   Nutrients, 2024 · checked 2026-10-07 · we read the abstract
4. ev-b12rls-04 · Observational data · retrospective case-control analysis · n = 160
   In addition, multivariate logistic regression revealed serum vitamin B12 to be independently associated with RLS (p < 0.05; odds ratio=0.97; 95 % confidence interval: 0.96-0.98).
   
   Who: 80 patients with RLS and 80 age- and gender-matched healthy controls, retrospective analysis
   Effect: serum B12 lower in RLS; OR 0.97 (95% CI 0.96 to 0.98) per unit; B12 weakly inversely correlated with IRLS score
   Certainty: Retrospective, single hospital; association, not cause; a meta-analysis of 21 studies did not confirm this.
   Clin Neurol Neurosurg, 2022 · checked 2026-10-07 · we read the abstract
5. ev-b12rls-05 · Observational data · cross-sectional study · n = 146
   Serum vitamin B12 levels were found to be significantly lower in patients with RLS compared to those without the syndrome.
   
   Who: 146 pediatric patients aged 10-16 years at outpatient clinics
   Effect: serum B12 significantly lower with RLS; RLS more frequent in the B12-insufficient group (unadjusted)
   Certainty: Cross-sectional, unadjusted analyses; the authors themselves write that causality is not established.
   Eur J Pediatr, 2026 · checked 2026-10-07 · we read the abstract
6. ev-b12rls-06 · Randomized controlled trial(s) · randomized, double-blind, placebo-controlled trial · n = 28
   After 3 months, 86% of the patients taking vitamin B had prominent remission of leg cramps, whereas those taking placebo had no significant difference from baseline.
   
   Who: 28 elderly patients with hypertension and severe nocturnal leg cramps; capsules three times daily for 3 months
   Effect: prominent remission in 86% on vitamin B complex vs no significant change on placebo
   Certainty: Complex: fursultiamine 50 mg, hydroxocobalamin 250 mcg, pyridoxal phosphate 30 mg, riboflavin 5 mg; the contribution of B12 is not separated; 1998, Taiwan, 14 per group.
   J Clin Pharmacol, 1998 · checked 2026-10-07 · we read the abstract
7. ev-b12rls-07 · Meta-analysis or systematic review · Cochrane systematic review of randomized controlled trials, GRADE · n = 1 trial, 42 women (review: 8 trials, 576 women)
   One small trial, did not report on frequency of leg cramps individually, but showed that oral vitamin B supplements may reduce the frequency and intensity (composite outcome) of leg cramps (RR 0.29, 95% CI 0.11 to 0.73; 1 study, 42 women).
   
   Who: pregnant women with leg cramps
   Effect: frequency and intensity composite RR 0.29 (95% CI 0.11 to 0.73); no data on side effects
   Certainty: Which B vitamin is not visible from the abstract (full text could not be extracted, no_fulltext); one small study.
   Cochrane Database Syst Rev, 2020 · checked 2026-10-07 · we read the abstract
8. ev-b12rls-08 · Position of an expert body · clinical practice guideline, GRADE · n = —
   In all patients with clinically significant RLS, clinicians should regularly test serum iron studies including ferritin and transferrin saturation (calculated from iron and total iron binding capacity).
   
   Who: adults and children with clinically significant restless legs syndrome
   Effect: test serum iron studies including ferritin and transferrin saturation in all patients with clinically significant RLS
   Certainty: The absence of B12 in the list of recommendations is from the abstract (the recommendations are listed there in full).
   J Clin Sleep Med, 2025 · checked 2026-10-07 · we read the abstract
9. ev-b12rls-09 · Position of an expert body · agency fact sheet · n = —
   The FNB did not establish a UL for vitamin B12 because of its low potential for toxicity [1].
   
   Who: general population
   Effect: no UL set by the Food and Nutrition Board
   Certainty: Safety does not make B12 a drug for RLS; a high dose has no established benefit for the legs.
   NIH Office of Dietary Supplements, Vitamin B12 fact sheet for health professionals · checked 2026-10-07 · we read the section
10. ev-b12rls-10 · Position of an expert body · agency fact sheet · n = —
    Vitamin B12 supplements may interact with medications, and some medications, including gastric acid inhibitors and metformin, may affect vitamin B12 levels.
    
    Who: people taking gastric acid inhibitors or metformin regularly
    Effect: lower B12 status; discuss testing with a clinician
    Certainty: Who should have B12 checked if the feet "burn" or go numb (neuropathy); not to be confused with RLS.
    NIH Office of Dietary Supplements, Vitamin B12 fact sheet for health professionals · checked 2026-10-07 · we read the section