Electrolytes
Electrolyte salts (sodium, potassium, chloride, citrate)
TL;DR
Electrolyte drinks help your body hold on to the fluid you drink, and oral rehydration solution is the standard treatment for dehydration from diarrhea. Most people don't need them day to day, and they don't prevent hyponatremia from overdrinking.
Ideal For
- Anyone with dehydration from diarrhea or vomiting (oral rehydration solution)
- Older adults during illness with fluid losses
- Athletes rehydrating after heavy sweating
- Long or hot training sessions and events
Avoid If
- You have chronic kidney disease or heart failure, unless your clinician advises it
- You take ACE inhibitors, ARBs or potassium-sparing diuretics, without checking first
- You've been told to limit sodium or fluids
- You're using them to drink well beyond thirst during endurance events
Frequently Asked Questions
Are electrolyte drinks better than water?
Do I need electrolytes every day?
Should I drink electrolytes when I have diarrhea?
Do electrolytes prevent hyponatremia in runners?
Can electrolytes stop muscle cramps?
Is an electrolyte drink safe if I have kidney disease?
Overview
Electrolytes are the charged minerals in body fluids, chiefly sodium, potassium and chloride, that decide where water goes in the body. An electrolyte supplement is any drink, powder or tablet that adds them to water. The products range from medical oral rehydration solution (ORS), built to a World Health Organization (WHO) specification of 75 mmol/L sodium, 20 mmol/L potassium and 75 mmol/L glucose, to sports drinks and zero-sugar tablets with far less sodium.
The strongest evidence is for ORS in dehydration caused by acute diarrhea, where Cochrane reviews have refined the formula over decades. For healthy people, controlled trials show that drinks with enough sodium are retained better than plain water: after exercise, the share of fluid the body keeps rises with the drink's sodium content, and at rest ORS left about 300 g less urine over 4 hours than the same volume of water. Typical sports drinks, with much less sodium, often perform no better than water.
What electrolytes don't do matters as much. Salt capsules did not improve a 3-hour cycling time trial, and in marathon and ultramarathon runners hyponatremia (low blood sodium) was driven by drinking too much, not by skipping electrolytes; sports drinks did not protect against it. For mild stomach bugs in otherwise healthy people, ordinary fluids work as well as electrolyte solution.
Most people get plenty of sodium from food already. US intake guidance is an adequate intake of 1,500 mg of sodium a day for adults, with advice to cut back if intake is above 2,300 mg, so daily high-sodium electrolyte mixes add to an intake that is usually already high. They make most sense around heavy sweating, illness with fluid losses, or in older adults at risk of dehydration.
How It Works
- Sodium and glucose are absorbed together in the small intestine, pulling water with them; this is the basis of oral rehydration solution.
- Sodium in a drink keeps plasma sodium and blood volume up, which reduces the urine output that follows drinking plain water.
- Retained sodium also sustains thirst, so people tend to keep drinking until losses are replaced.
- Potassium replaces intracellular losses from diarrhea and vomiting; chloride and citrate help correct acid-base balance.
- Plain water after heavy sweating dilutes blood sodium and chloride; electrolyte drinks keep them stable.
Quick Facts
- ORS is the standard treatment for diarrheal dehydration
- Sodium content decides how much fluid you keep
- Typical sports drinks often hydrate no better than water
- Electrolytes don't prevent overdrinking hyponatremia
- Mild stomach bugs: ordinary fluids work as well
Health Concerns Addressed
Frequent Diarrhea
Strong evidence that oral rehydration solution treats dehydration from diarrhea; it doesn't stop diarrhea, and mild cases rarely need it.
Muscle Cramps
Small lab trials favour an electrolyte solution over plain water, but race studies point to fatigue and prior cramps, not electrolyte loss.
Hyponatremia
Salt tablets and sports drinks don't prevent hyponatremia from overdrinking; drinking to thirst does.
Supporting Research42 studies
Sodium supplementation is not required to maintain serum sodium concentrations during an Ironman triathlon
Hew-Butler TD, Sharwood K, Collins M +2 more
Ad libitum sodium supplementation was not necessary to preserve serum sodium concentrations
A randomized trial to assess the potential of different beverages to affect hydration status: development of a beverage hydration index
Maughan RJ, Watson P
The mean BHI at 2 h was 1.54 ± 0.74 for the ORS
Post-exercise rehydration in man: effects of volume consumed and drink sodium content
Shirreffs SM, Taylor AJ, Leiper JB +1 more
both sodium concentration and fluid volume consumed interact to affect the rehydration process
Sodium intake and post-exercise rehydration in man
Maughan RJ, Leiper JB
the fraction of the ingested fluid that was retained was directly related to the sodium concentration
Effect of oral rehydration solution versus spring water intake during exercise in the heat on muscle cramp susceptibility of young men
Lau WY, et al
ORS intake during exercise decreased muscle cramp susceptibility
Effect of Sodium Supplements and Climate on Dysnatremia During Ultramarathon Running
Lipman GS, Burns P, Phillips C +4 more
Sodium supplementation did not prevent EAH nor cause hypernatremia
Reduced osmolarity oral rehydration solution for treating dehydration caused by acute diarrhoea in children
Hahn S, Kim S, Garner P
reduced osmolarity ORS was associated with fewer unscheduled intravenous fluid infusions
Effects of different sodium concentrations in replacement fluids during prolonged exercise in women
Twerenbold R, Knechtle B, Kakebeeke TH +4 more
This can be minimised by the use of replacement fluids of high sodium concentration
A randomized trial to assess beverage hydration index in healthy older adults
Clarke MM, Stanhewicz AE, Wolf ST +3 more
Beverage Na+ content progressively increased BHI in young adults
Effect of Dilute Apple Juice and Preferred Fluids vs Electrolyte Maintenance Solution on Treatment Failure Among Children With Mild Gastroenteritis: A Randomized Clinical Trial
Freedman SB, Willan AR, Boutis K +1 more
Its advantage in minimally dehydrated children is unproven.
The Beverage Hydration Index: Influence of Electrolytes, Carbohydrate and Protein
Sollanek KJ, Kenefick RW
Electrolyte content appears to make the largest contribution in hydration properties of beverages
Polymer-based oral rehydration solution for treating acute watery diarrhoea
Gregorio GV, Gonzales ML, Dans LF +1 more
Glucose-based oral rehydration solution (ORS) helps replace fluid and prevent further dehydration from acute diarrhoea
Sodium Supplementation and Exercise-Associated Hyponatremia during Prolonged Exercise
Hoffman MD, Stuempfle KJ
overhydration is the primary characteristic of those developing hyponatremia
Sodium supplementation has no effect on endurance performance during a cycling time-trial in cool conditions: a randomised cross-over trial
Cosgrove SD, Black KE
Sodium supplements had no effect on time-trial performance
Hyponatremia among runners in the Boston Marathon
Almond CS, Shin AY, Fortescue EB +4 more
female sex, composition of fluids ingested, and use of nonsteroidal antiinflammatory drugs were not
Influence of Hydration and Electrolyte Supplementation on Incidence and Time to Onset of Exercise-Associated Muscle Cramps
Jung AP, Bishop PA, Al-Nawwas A +1 more
carbohydrate-electrolyte beverage before and during exercise in a hot environment may delay the onset
Increased running speed and previous cramps rather than dehydration or serum sodium changes predict exercise-associated muscle cramping: a prospective cohort study in 210 Ironman triathletes
Schwellnus MP, Drew N, Collins M
dehydration and altered serum electrolyte balance are not causes for EAMC
Serum electrolyte concentrations and hydration status are not associated with exercise associated muscle cramping (EAMC) in distance runners
Schwellnus MP, Nicol J, Laubscher R +1 more
no clinically significant alterations in serum electrolyte concentrations
Muscle Cramping During a 161-km Ultramarathon: Comparison of Characteristics of Those With and Without Cramping
Hoffman MD, Stuempfle KJ
use of sodium supplements, intake rate of sodium in supplements
Muscle Cramping in the Marathon: Dehydration and Electrolyte Depletion vs. Muscle Damage
Martínez-Navarro I, Montoya-Vieco A, Collado E +3 more
did not exhibit a greater degree of dehydration and electrolyte depletion
Muscle Cramping in Ultra-Trail: Dehydration and Electrolyte Depletion versus Muscle Damage
Martinez-Navarro I, Vicente-Mampel J, López-Grueso R +4 more
did not exhibit a greater degree of postrace dehydration and sodium depletion
Sodium replacement and plasma sodium drop during exercise in the heat when fluid intake matches fluid loss
Anastasiou CA, Kavouras SA, Arnaoutis G +4 more
sodium intake during prolonged exercise in the heat plays a significant role
A randomized, cross-over trial assessing effects of beverage sodium concentration on plasma sodium concentration and plasma volume during prolonged exercise in the heat
Wijering LAJ, Cotter JD, Rehrer NJ
those who fully hydrate would benefit by increased sodium content of the beverage
Sodium-free fluid ingestion decreases plasma sodium during exercise in the heat
Vrijens DM, Rehrer NJ
We, therefore, recommend consumption of a sodium-containing beverage to compensate for large sweat losses
Three independent biological mechanisms cause exercise-associated hyponatremia: evidence from 2,135 weighed competitive athletic performances
Noakes TD, Sharwood K, Speedy D +4 more
EAH can be prevented by insuring that athletes do not drink to excess during exercise
Exercise-associated hyponatremia and hydration status in 161-km ultramarathoners
Hoffman MD, Hew-Butler T, Stuempfle KJ
excessive sodium supplementation and aggressive fluid ingestion beyond the dictates of thirst are ill advised
Efficacy of Furosemide, Oral Sodium Chloride, and Fluid Restriction for Treatment of Syndrome of Inappropriate Antidiuresis (SIAD): An Open-label Randomized Controlled Study (The EFFUSE-FLUID Trial)
Krisanapan P, Vongsanim S, Pin-On P +2 more
furosemide with NaCl supplement in combination with fluid restriction did not show benefits
Reflex inhibition of electrically induced muscle cramps in hypohydrated humans
Miller KC, Mack GW, Knight KL +4 more
could not be explained by rapid restoration of body fluids or electrolytes
Risk Factors for Exercise-Associated Muscle Cramps: A Systematic Review With Meta-Analysis
Costa LDS, Correa VAF, de Oliveira VF +3 more
The uncertainties regarding hydration status, electrolyte balance
Reduced osmolarity oral rehydration solution for treating cholera
Murphy C, Hahn S, Volmink J
reduced osmolarity ORS is associated with biochemical hyponatremia when compared with standard ORS
Oral Hypertonic Saline Is Effective in Reversing Acute Mild-to-Moderate Symptomatic Exercise-Associated Hyponatremia
Bridges E, Altherwi T, Correa JA +1 more
Oral HTS is effective in reversing symptoms of mild-to-moderate hyponatremia in EAH
Serum electrolytes in Ironman triathletes with exercise-associated muscle cramping
Sulzer NU, Schwellnus MP, Noakes TD
clinically significant differences in serum electrolyte concentrations
Impact of Nuun Electrolyte Tablets on Fluid Balance in Active Men and Women
Pence J, Bloomer RJ
fluid balances for both concentrations more favorable compared to water
Three percent hypohydration does not affect threshold frequency of electrically induced cramps
Miller KC, Mack GW, Knight KL +4 more
more associated with neuromuscular fatigue than dehydration/electrolyte losses
The Role of Electrolytes in Muscle Pain Syndromes: A Systematic Review and Meta-Analysis With Implications for Temporomandibular Disorder
Patil S, Falkowski A, Venkataiah VS +3 more
Sodium-based interventions are context-specific
Water intake after dehydration makes muscles more susceptible to cramp but electrolytes reverse that effect
Lau WY, Kato H, Nosaka K
water intake after dehydration makes muscles more susceptible to electrical simulation-induced muscle cramp
Electrolyte and plasma responses after pickle juice, mustard, and deionized water ingestion in dehydrated humans
Miller KC
did not fully replenish electrolytes and fluid losses
An intervention study of oral versus intravenous hypertonic saline administration in ultramarathon runners with exercise-associated hyponatremia: a preliminary randomized trial
Rogers IR, Hook G, Stuempfle KJ +2 more
a similar effect was not demonstrated for the same dose orally
Case Study: Symptomatic Exercise-Associated Hyponatremia in an Endurance Runner Despite Sodium Supplementation
Hoffman MD, Myers TM
oral sodium supplementation does not necessarily prevent symptomatic EAH
Statement of the 3rd International Exercise-Associated Hyponatremia Consensus Development Conference, Carlsbad, California, 2015
Hew-Butler T, Rosner MH, Fowkes-Godek S
a preventable and treatable fluid imbalance
A randomized controlled trial of glucose versus amylase resistant starch hypo-osmolar oral rehydration solution for adult acute dehydrating diarrhea
Ramakrishna BS, Subramanian V, Mohan V +4 more
HAMS-ORS reduced diarrhea duration by 55%
The effects of a sugar-free amino acid-containing electrolyte beverage on 5-kilometer performance, blood electrolytes, and post-exercise cramping versus a conventional carbohydrate-electrolyte sports beverage and water
McIntosh MC, Ruple BA, Kontos NJ +3 more
favorable effects on blood electrolyte and post-exercise self-reporting cramp outcomes
Safety Information
Potential Side Effects
Generally well tolerated. Strong or oversalted mixes can cause nausea or worsen diarrhea; making up powders with too little water raises their concentration. Regular high-sodium products add to total sodium intake.
Contraindications
Chronic kidney disease, heart failure or any condition where you have been told to restrict sodium, potassium or fluids. Severe dehydration, confusion or inability to keep fluids down need medical care rather than home rehydration.
Drug Interactions
- ACE inhibitors, angiotensin receptor blockers and potassium-sparing diuretics: potassium-containing products can raise blood potassium; check with your prescriber.
- Blood pressure medicines in general: high-sodium mixes can work against sodium restriction; ask your clinician how much sodium is right for you.
- Diuretics: change sodium and potassium handling; use electrolyte products only as your prescriber advises.
Pregnancy & Breastfeeding
Pregnancy: Likely safe
Breastfeeding: Likely safe
Dosage Guidelines
Dosage Used in Studies
Consult healthcare provider
Best Time to Take
When losses happen: during illness with diarrhea or vomiting, during long or hot exercise, and in the hours after heavy sweating.
Best Form
Oral rehydration solution for illness; a higher-sodium electrolyte drink or water plus food after heavy sweating.
Bioavailability
Sodium and glucose are absorbed together in the small intestine, which is why oral rehydration solution contains both in a set ratio.
Dosing by Goal
| Goal | Dose | Notes |
|---|---|---|
| Dehydration from diarrhea or vomiting | Oral rehydration solution made up exactly as directed (WHO formula: 75 mmol/L sodium, 75 mmol/L glucose) | Sip small amounts often and keep going while losses continue; aim to keep passing urine regularly. Seek care for signs of severe dehydration. |
| After exercise with heavy sweating | About 1.5 times the weight lost (1.5 L per kg), with a drink containing roughly 50 mmol/L sodium or more, or water with a salty meal | Weigh before and after exercise to estimate losses. Lower-sodium drinks are mostly urinated away. |
| During long exercise | Drink to limit weight loss to under about 2% of body weight; carbohydrate-electrolyte drinks can help in long or hot sessions | Never drink so much that you gain weight; that is what causes exercise-associated hyponatremia. |
| Everyday hydration | Usually unnecessary; water and normal meals cover most people | US guidance: adequate intake 1,500 mg sodium a day; reduce intake if above 2,300 mg. |
Forms Compared
Oral rehydration solution (ORS)
Best for Dehydration from diarrhea or vomiting
Medical formula: about 60-75 mmol/L sodium, 20 mmol/L potassium and 75-90 mmol/L glucose (reduced osmolarity, about 245 mOsm/L). Sold in pharmacies as sachets or ready-mixed.
Sports drinks (carbohydrate-electrolyte)
Best for Long or hot exercise sessions
Lower sodium (often around 20 mmol/L) plus 6-8% carbohydrate. Fuel for long exercise; not adequate alone for severe diarrhea.
Electrolyte powders and tablets
Best for Heavy sweaters, post-exercise rehydration
Dissolve in water; sodium ranges widely between products, so check the label. Often sugar-free.
Salt capsules
Best for Very long events in heat, by experienced athletes
Sodium without fluid; used by endurance athletes. Trials show no performance benefit in cool conditions.
Food & Timing
Can be taken with or without food; a salty meal with water does a similar job after exercise.
Medical Disclaimer
The information provided on this website is for educational and informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting any supplement regimen.
Individual results may vary. The statements on this website have not been evaluated by the Food and Drug Administration. Products and information are not intended to diagnose, treat, cure, or prevent any disease.