Does low sodium cause muscle cramps?

For most people there is no evidence that it does. We found no trial that tested low sodium in the diet as a cause of cramps. The one setting where less sodium clearly goes with more cramps is the dialysis unit. A Cochrane review of people on hemodialysis found that dialysis fluid low in sodium probably increases cramps during dialysis by 84 percent (risk ratio 1.84, 95% CI 1.29 to 2.64), on moderate-certainty evidence across 10 studies and 14,559 sessions. The review abstract gives no absolute numbers, and the sodium in question is in the dialysis fluid. Food was not studied. In endurance athletes, the people the question usually comes from, those who cramp have blood sodium in the normal range.

Myth. The picture of a cramping athlete who has sweated their blood sodium away has been checked in three groups of endurance athletes. Across 30 years of Ironman World Championship medical records, 10,533 in all, athletes treated for cramps did not differ in serum sodium from other athletes. They had lost more weight. These are observational data from the medical tent, so they describe who cramped and cannot show what caused it.

Cramps with less sodium, and with added sodium

Meta-analyses of randomized trials

The dialysis row is a risk ratio for cramps during dialysis when the dialysis fluid holds less sodium, so above 1 means more cramps. The pregnancy row is an odds ratio for sodium chloride against placebo, and its interval crosses 1, so it shows no clear benefit. The two come from different questions and different people. Sources: cards ev-nacr-05 and ev-nacr-03 below.

What the trials found

Sodium drinks for cramps

A 2026 meta-analysis gathered 13 randomized or quasi-randomized trials of magnesium, sodium, calcium and potassium for cramps or muscle pain, searched from 1995 to August 2025. Sodium-based solutions reduced cramp susceptibility in exercise and in cirrhosis. Only three of the 13 trials tested sodium or mixed electrolyte drinks, all small, in different people, and the review gives no pooled number for sodium.

One of those three gave an oral rehydration solution during exercise in the heat and found it lowered susceptibility to cramps that the researchers set off with electrical stimulation, compared with spring water. Another, a randomized crossover trial in 9 cramp-prone young adults, used a drink with 840 mg of sodium. The electrical frequency needed to set off a cramp rose from 14.00 to 14.86 Hz and pain fell from 2.7 to 2.0, yet the drink did not prevent cramping in any participant. Both trials measured cramps provoked in the lab, which are a different thing from the cramp that wakes you at night or stops you late in a race. The second drink also carried potassium and carbohydrate.

Pickle juice in cirrhosis

In a randomized trial of 82 people with cirrhosis and more than four cramps in the previous month, 74 of whom finished, sips of pickle juice at the start of a cramp cut cramp severity by 2.25 points on a 10-point scale over 28 days, against 0.36 with tap water (P = 0.03). Sleep quality did not change differently between the groups. The trial was not blinded, and people with cirrhosis are a particular group. A separate crossover trial in 9 healthy men found that about 2.9 fl oz (86 ml) of pickle juice did not change blood sodium, potassium or plasma volume within 60 minutes. So if pickle juice eases a cramp, the data do not show it working by topping up sodium in the blood.

Salt in pregnancy

A Cochrane review of 5 trials with 352 pregnant women found no clear benefit of sodium chloride over placebo for leg cramps, with an odds ratio of 0.54 and a confidence interval from 0.23 to 1.29. That interval runs from a large benefit to some harm, so the trials cannot tell. The review dates from 2002, and its later updates no longer analyze sodium.

Eating less salt

If low dietary sodium caused cramps, trials that cut salt would be the place to see it. An AHRQ systematic review of sodium reduction trials found too little evidence to judge side effects such as dizziness, headache and cramps. The one trial that reported cramps saw them improve in both groups. That is an absence of data, and it is all there is.

Dialysis, the exception

On hemodialysis the answer changes, and it is the only part of this question with solid numbers. Beyond the Cochrane review above, a 2024 systematic review of 13 trials of drugs and supplements for dialysis cramps included sodium chloride among nine treatments. Vitamins C and E had the most consistent positive results, and the abstract gives no estimate for sodium chloride.

Runners who cramp

In 72 ultramarathon runners, those who cramped finished with serum sodium of 139.8 mmol/l against 142.3 in runners who did not. Both are in the normal range, and the authors found no clinically significant electrolyte change and no difference in hydration. A small case-control study of 20 Ironman finishers found the same, 140 against 143 mmol/L, and linked cramping to higher electrical activity in the cramping muscle. Both samples are small and from single races.

Unsettled. Sodium drinks did lower cramp susceptibility in lab-provoked cramps and in cirrhosis, in three small trials. Nobody has run a blinded trial of sodium for the cramps people actually get, in athletes or in older adults at night. Until someone does, a sports drink for cramps is a guess with a small amount of lab support behind it.

Who should be careful

Not for everyone. Salt tablets are the thing to avoid. Among 1152 ultramarathon runners, 59 percent believed sodium supplements prevent cramping, and the authors of that survey wrote that the accumulating evidence shows sodium supplements during ultramarathons are unnecessary and may be dangerous. That warning is their reading of the literature. Their own survey measured beliefs only. CDC NIOSH tells workers with heat cramps to avoid salt tablets.

If you have been told to limit sodium, for heart, liver or kidney reasons, salty remedies are a real dose. In the pickle juice trial, the ethics board capped people on sodium restriction at 3 tablespoons of pickle juice a day because of the risk of fluid overload. That cap was a precaution, and nobody tested it as a safe limit. If you are on dialysis and cramp during sessions, the sodium level in your dialysis fluid is a question for your renal team. Whether eating less salt brings on cramps or other side effects has too little data to say either way.

What expert bodies say

CDC NIOSH advises workers with heat cramps to drink water and have a snack or a sports drink every 15 to 20 minutes, and to avoid salt tablets. It says to get medical help for someone with heart problems, someone on a low sodium diet, or cramps that last longer than an hour. CDC explains heat cramps by salt lost in sweat, while the athlete studies above find normal blood sodium in people who cramp. That gap between the agency and the research is unresolved. We could not obtain the 2015 NATA position statement on exertional heat illness, and the European hyponatremia guideline abstract does not mention cramps.

How we searched

Searched: a local copy of the PubMed baseline for sodium, salt, electrolytes, hyponatremia or oral rehydration with cramps, all publication types (122 records), and the same search widened to dehydration and sweat, scanned to the first 100 rows. Also exercise-associated muscle cramps (10 records), oral rehydration with cramps (none relevant) and hyponatremia guidelines. The local PMC full-text base for the 2026 meta-analysis and the pickle juice trial. Agency reviews for sodium and cramps, which returned the AHRQ 2018 review. A local index of ClinicalTrials.gov for pickle juice and sodium with cramps found no trials. Web searches for newer reviews, hyponatremia guidelines, the NATA position statement and the CDC page. All included papers were checked against Retraction Watch. Searches run on 7 October 2026.

Included: the 2026 electrolyte meta-analysis, the Cochrane reviews of dialysis fluid sodium (2024) and of leg cramps in pregnancy (2002), the AHRQ 2018 review, a 2024 review of dialysis cramp treatments, three randomized trials (pickle juice in cirrhosis, an electrolyte drink, pickle juice and blood sodium), four observational studies of endurance athletes and the CDC NIOSH heat illness page.

Excluded: the 2019 version of the dialysis Cochrane review, replaced by the 2024 one. The 2015 and 2020 Cochrane pregnancy updates, which have no sodium arm. Magnesium reviews, which answer a different question. A narrative-style review with no extractable sodium numbers. Studies of amino acid electrolyte products where cramping meant gut cramps. Case reports of inherited salt wasting disorders, which are diseases and say nothing about diet.

What we read: abstracts for most studies, the full text of the 2026 meta-analysis results and of the pickle juice trial methods, the relevant section of the AHRQ review and the CDC page.

What we could not get: the NATA 2015 position statement, blocked or missing at every source we tried. Full texts of the 2024 dialysis Cochrane review and the 2024 dialysis cramp review, so their numbers come from abstracts. The NICE leg cramps summary, which refused access.

What would change this answer

A blinded randomized trial of sodium for natural cramps, in athletes or in older adults with night cramps, with cramps counted as the outcome. We found none running in our local index of ClinicalTrials.gov.
Trials in people on diuretics or low-sodium diets that record cramps. These are the people for whom low sodium is a realistic exposure, and the AHRQ review found almost nothing on them.
A current review of salt for cramps in pregnancy. The only analysis of sodium there dates from 2002.

For where sodium comes from in food, see the salt page.

The rest of the nutrient, in one place. Sodium: what lowering it actually does to blood pressure and to death rates → What it does, how much you need, who runs short, and what too much does, with the evidence level shown on every line.

The food behind this question

Pink salt, sea salt and the iodine you lose — numbers, evidence and safety

The full guide

Sodium: what lowering it actually does to blood pressure and to death rates

The same question for other foods (muscle cramps)

Sources

ev-nacr-01 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized trials · n = 13 trials (3 on sodium or multi-electrolyte drinks)
Sodium-based solutions reduced cramp susceptibility in exercise and cirrhosis, while calcium and potassium lacked supportive evidence.
Who: randomized or quasi-randomized trials of magnesium, sodium, calcium or potassium supplementation for cramps or myalgia, searched 1995 to August 2025
Effect: sodium-based solutions reduced cramp susceptibility in exercise and cirrhosis; no pooled estimate for sodium
Certainty: There are only three sodium RCTs, small, different populations; no pool for sodium. Cramps from sodium deficiency in the diet were not studied.
Int Dent J, 2026 · checked 2026-10-07 · we read the abstract
ev-nacr-02 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized trials · n = 3 trials
Lau et al36 found that an oral rehydration solution consumed during exercise in the heat decreased electrically induced cramp susceptibility compared with spring water, an effect attributed to maintenance of sodium and chloride balance.
Who: trials of sodium or multi-electrolyte beverages within the 2026 electrolyte meta-analysis
Effect: ORS during exercise in heat decreased electrically induced cramp susceptibility vs spring water
Certainty: Seizures were induced by electrical stimulation in the lab, not natural seizures.
Int Dent J, 2026 · checked 2026-10-07 · we read the fulltext
ev-nacr-03 · Meta-analysis or systematic review · Cochrane systematic review of randomized trials · n = 5 trials, 352 women
Trials comparing sodium chloride with placebo (odds ratio 0.54, 95% confidence interval 0.23 to 1.29) and calcium with sodium chloride (odds ratio 1.23, 95% confidence intervals 0.47 to 3.27 ) showed no evidence of benefit.
Who: pregnant women with leg cramps in randomized trials
Effect: sodium chloride vs placebo OR 0.54 (0.23-1.29); calcium vs sodium chloride OR 1.23 (0.47-3.27)
Certainty: 2002 version; the 2015 and 2020 updates no longer analyze sodium. The authors themselves write that the sodium study may have become outdated because of the higher sodium in the modern diet.
Cochrane Database Syst Rev, 2002 · checked 2026-10-07 · we read the abstract
ev-nacr-04 · Meta-analysis or systematic review · agency systematic review · n = 5 RCTs on dizziness, headache, insulin sensitivity and muscle cramping
One study reported improvements in muscle cramps across both groups.
Who: adults in RCTs of sodium reduction
Effect: muscle cramps improved in both groups in one trial; evidence insufficient
Certainty: Search up to 2017. Key for the question: lowering dietary salt gave no signal about cramps, but data are few.
AHRQ, 2018, Sodium and Potassium Intake: Effects on Chronic Disease Outcomes and Risks (Comparative Effectiveness Review 206) · checked 2026-10-07 · we read the section
ev-nacr-05 · Meta-analysis or systematic review · Cochrane systematic review and meta-analysis of RCTs · n = 17 studies, 509 patients; cramps outcome 10 studies, 14,559 sessions
Compared to neutral or high dialysate [Na+], low dialysate [Na+] probably increases intradialytic hypotension events (13 studies, 15,764 HD sessions: RR 1.58, 95% 1.25 to 2.01; moderate certainty evidence) and intradialytic cramps (10 studies, 14,559 HD sessions: RR 1.84, 95% 1.29 to 2.64; moderate certainty evidence).
Who: maintenance hemodialysis patients, dialysate sodium below 138 mM vs 138 mM or higher
Effect: intradialytic cramps RR 1.84 (1.29-2.64), moderate certainty
Certainty: This is sodium in dialysis solution, not in food; the only context with good data where lower sodium gives more cramps.
Cochrane Database Syst Rev, 2024 · checked 2026-10-07 · we read the abstract
ev-nacr-06 · Meta-analysis or systematic review · systematic review · n = 13 studies
The studies reported on nine interventions: vitamin C, vitamin E, vitamin K2, vitamin B7, dextrose solutions, gabapentin, sodium chloride, creatine monohydrate, and L-carnitine.
Who: experimental studies of pharmacological interventions for dialysis-related muscle cramps, searched to August 2023
Effect: sodium chloride among 9 interventions; vitamins C and E most studied with positive results; no pooled estimate
Certainty: No meta-analysis; the abstract does not give an estimate for NaCl specifically.
Semin Dial, 2024 · checked 2026-10-07 · we read the abstract
ev-nacr-07 · Randomized controlled trial(s) · randomized controlled trial · n = 82 (74 completed)
At trial completion, the respective values for the pickle juice and control arms were -2.25 ± 3.61 points on the VAS for cramps, compared with control tap water (-0.36 ± 2.87), P = 0.03; a proportion of cramp-days with VAS-cramps <5 were 46% vs 35% (P = 0.2); and the change in sleep quality was not different (P = 0.1).
Who: patients with cirrhosis and >4 muscle cramps in the previous month
Effect: VAS-cramps change -2.25 +/- 3.61 vs -0.36 +/- 2.87 with tap water, P = 0.03; sleep and quality of life not different
Certainty: Not blinded; the marinade probably acts reflexively via the mouth, not by replenishing sodium. Cirrhosis is a special group.
Am J Gastroenterol, 2022 · checked 2026-10-07 · we read the abstract
ev-nacr-08 · Randomized controlled trial(s) · randomized controlled trial · n = 82
The IRB raised concerns regarding the risk of volume overload and required that patients requiring sodium restriction were instructed to drink no more than 3 tablespoons of pickle juice per day.
Who: patients with cirrhosis in the PICCLES trial
Effect: dose about 1 tablespoon at cramp onset; maximum 3 tablespoons/day if on sodium restriction
Certainty: The limit was imposed by the ethics committee; it is not a tested safe limit.
Am J Gastroenterol, 2022 · checked 2026-10-07 · we read the fulltext
ev-nacr-09 · Randomized controlled trial(s) · randomized placebo-controlled crossover trial · n = 9
EB consumption decreased cramp susceptibility and pain but did not prevent cramping in any participants.
Who: euhydrated, cramp-prone young adults; electrolyte beverage (Na 840 mg, K 320 mg) vs placebo (Na 35 mg)
Effect: threshold frequency 14.86 vs 14.00 Hz (P = .038); pain 2.0 vs 2.7 (P = .025); EMG similar
Certainty: Very few participants, artificial cramps from electrical stimulation, the drink also contained potassium and carbohydrates.
Muscle Nerve, 2019 · checked 2026-10-07 · we read the abstract
ev-nacr-10 · Randomized controlled trial(s) · randomized crossover trial · n = 9
At these volumes, ingestion of pickle juice and CHO-e drink did not cause substantial changes in plasma electrolyte concentrations, plasma osmolality, or plasma volume in rested, euhydrated men.
Who: euhydrated healthy men, 1 mL/kg body mass of pickle juice, carbohydrate-electrolyte drink or water
Effect: no substantial change in plasma electrolytes, osmolality or plasma volume over 60 min
Certainty: So a small sip does not replenish sodium losses; if the brine does act on cramps, it is not through blood sodium.
J Athl Train, 2009 · checked 2026-10-07 · we read the abstract
ev-nacr-11 · Observational data · prospective cohort · n = 72
There are no clinically significant alterations in serum electrolyte concentrations and there is no alteration in hydration status in runners with EAMC participating in an ultra-distance race.
Who: runners in an ultra-distance road race; cramp group n = 21, control n = 22
Effect: post-race serum sodium 139.8 (3.1) vs 142.3 (2.1) mmol/l, p = 0.004; no clinically significant differences
Certainty: Small sample, one race.
Br J Sports Med, 2004 · checked 2026-10-07 · we read the abstract
ev-nacr-12 · Observational data · retrospective analysis of prospectively collected data · n = 10,533 records among 49,530 participants; 2863 EAMC
Athletes with EAMC had greater weight loss but did not differ in serum sodium and serum potassium compared with those without EAMC.
Who: IRONMAN World Championship medical tent records 1989-2019
Effect: EAMC 57.8 per 1000 participants (55.7-60.0); serum sodium no difference
Certainty: Only those who reached the medical tent; association, not cause.
Clin J Sport Med, 2026 · checked 2026-10-07 · we read the abstract
ev-nacr-13 · Observational data · case-control study · n = 20
Acute EAMC in ironman triathletes is not associated with a greater percent body mass loss or clinically significant differences in serum electrolyte concentrations.
Who: South African Ironman 2000 finishers, 11 crampers vs 9 matched controls
Effect: post-race sodium 140 vs 143 mmol/L, within normal range
Certainty: Very small sample.
Med Sci Sports Exerc, 2005 · checked 2026-10-07 · we read the abstract
ev-nacr-14 · Observational data · cross-sectional survey within a longitudinal cohort · n = 1152
In the past, ultramarathon runners have commonly believed that consuming sodium supplements, as capsules or tablets, will prevent exercise-associated hyponatremia (EAH), dehydration, muscle cramping, and nausea, but accumulating evidence indicates that sodium supplementation during ultramarathons is not necessary and may be potentially dangerous.
Who: participants of the Ultrarunners Longitudinal TRAcking (ULTRA) study, 2018
Effect: 66.4% want sodium supplements available; 59.1% believe they prevent cramping
Certainty: The claim of danger is the authors' conclusion from the literature, not their own data.
Appl Physiol Nutr Metab, 2020 · checked 2026-10-07 · we read the abstract
ev-nacr-15 · Position of an expert body · agency guidance · n = —
Avoid salt tablets.
Who: workers with heat cramps
Effect: avoid salt tablets; seek medical help if heart problems, low sodium diet, or cramps over 1 hour
Certainty: CDC explains heat cramps by loss of salt in sweat, whereas studies of athletes do not see a link with serum sodium. A discrepancy between the agency and science.
CDC NIOSH, Heat-related Illnesses (heat cramps), last reviewed 3 March 2026 · checked 2026-10-07 · we read the section

How this page was made. Evidence was extracted from primary sources into cards, every number was re-checked against the source, and the text was written from those cards. Bioma Learn has no human medical reviewer at this time, and we say so rather than invent one. Methodology. This is information, not medical advice.