Electrolytes
A mixture of minerals the body loses in fluid, sold to replace them.
- Cramp
- Stomach upsets
A plain-English overview, not advice. Written from published reviews and trials and from what people say in public forums.
Compare electrolytes prices per dose
On this page
What is electrolytes?
Electrolytes are not one substance but a group of minerals the body keeps dissolved in its fluids: sodium, potassium, magnesium and calcium, with chloride alongside them. Most of what people get arrives in food and drink, with salt supplying sodium and chloride, and fruit, vegetables, nuts and pulses named in the reviews as the main sources of potassium. Bought as a supplement they come as tablets, sachets, powder or capsules, and what is in the tub is the mixture, so the label describes a serving rather than one amount. Drinks of this kind have long been given to put fluid and salts back when losses run high, and that idea of replacing what has gone out is what the tablets and sachets on the shelf are built around.
Why do people take electrolytes?
Cramp
The thinking. Cramp sends a lot of people to electrolyte tablets: the night-time seize in a calf, the twinge that arrives late in a long run, the cramps that come with pregnancy. The idea is that a cramping muscle is one firing when it should not, and that magnesium, sodium, potassium and calcium are the minerals nerve and muscle signalling runs on.
What research has found. One review pooled thirteen randomised trials of electrolytes given for cramp or muscle pain, ten of them of magnesium. In the pregnancy trials cramps came less often; in trials of night-time or persistent leg cramps in adults there was no clear difference either way. Drinks based on sodium came out differently again, making cramp harder to bring on during exercise, and few trials had looked at calcium or potassium for this. Studies here point in different directions, so this one is still being worked out; the dose, how long people took it and who took part all seem to matter.
Stomach upsets
The thinking. The other everyday reason is a bout of sickness or diarrhoea, when fluid leaves fast and takes salts with it. Sachets and tablets are sold for exactly that, and the thinking behind them is arithmetic: what goes out has to come back, and water on its own puts back only part of it.
What research has found. One trial gave 647 children aged six months to five years, all with a mild stomach upset and little sign of dehydration, either a flavoured electrolyte solution or diluted apple juice and then whatever they preferred to drink. Over the following week, fewer of the children given the juice needed further care, about one in six against one in four. How often they were sick or had diarrhoea did not differ. Few studies have measured this yet, so there is little to go on either way.
What does electrolytes do in the body?
Electrolytes are minerals the body keeps dissolved in its fluids, and the work is done by holding each of them inside a narrow range rather than by burning any of them as fuel. The kidneys do most of that holding. Reviews of fluid balance describe chloride as the main thing setting how concentrated the blood is, and sodium as the one the body hangs on to, or lets go of, when it is managing fluid.
When the balance tips, it shows. Reviews describe a body carrying too much sodium and run down on potassium as one that dries out more easily, particularly inside its cells, and they trace the effects of sodium, potassium, calcium or magnesium running high or low through the nerves and the muscles. The same minerals turn up in the research on diet, where higher potassium, magnesium and calcium track with lower blood pressure and high sodium with the opposite, which is why guidance on salt is usually paired with guidance on potassium.
What do people say about taking electrolytes?
These are anecdotes people have shared, not evidence.
What people like
- Four of these six threads are cycling forums and two are parenting boards, so the reasons split between long rides and being unwell.
- On the cycling threads cramp is the commonest thing people credit them with, several saying it stopped once they started using tablets.
- Hangovers come up unprompted in two of the cycling threads, with a good handful saying a tablet in water is what they reach for.
- A few riders describe feeling fresher the next day after a hard session, and noticing the difference on days they forget.
- On the parenting boards several use sachets through a bout of illness or a gut condition, and pick whichever flavour they can drink.
Common complaints
- Taste is the commonest grumble and comes up on both kinds of board: salty, too strong, or only drinkable once well diluted.
- Cost is the next: several say the ones they like are dear, and hunt for cheaper tablets or buy powder by the tub.
- Every cycling thread carries someone doubting the cramp link, saying the science is unsettled or putting cramp down to hydration or training instead.
- A few mention strength: diluting further, passing more water at higher concentrations, and one warning against going over the stated dose.
How people take it
- One tablet to a bottle, or one to a two-litre bladder, is the dose described most often on the cycling threads.
- Many take them only in hot weather or on rides past an hour or two, and drink plain water otherwise.
- Timing varies a lot: before setting off, sipped through the ride, after getting home, or the day before a race.
- Home-made versions are common: squash with salt and sugar, a spoonful of sea salt, or powder bought by the bag.
- On the parenting boards sachets are sipped through the day while unwell, and a couple describe dissolving or sucking tablets to make the taste bearable.
Read from these public discussions:
- Electrolyte question (Singletrack World forum, 2018)
- Salt tablets (Singletrack World forum, 2019)
- Electrolyte tablets - when to drink them? (Singletrack World forum, 2012)
- Drink water or electrolytes more? (Road Bike Review cycling forum, 2011)
- Electrolyte sachets which you add to water (Mumsnet, 2025)
- Need something for rehydration (Mumsnet, 2024)
What forms of electrolytes are there?
| Form | What’s different | Per serving, on products we list |
|---|---|---|
| Electrolytes (per serving) | Sold as tablets, sachets, powder or capsules; the label gives the minerals in one serving. | 1 serving |
What else is worth knowing about electrolytes?
- Labels give what is in one serving, and a serving may be more than one tablet or scoop. Because the product is a mixture rather than a single substance, prices here are lined up per daily serving rather than per milligram.
- Sodium can run high as well as low. The one review behind this page that looked at sodium given on its own was in babies born early: alongside better weight gain it recorded blood sodium running high in about a third of the supplemented groups, and its authors asked for close monitoring and doses worked out for each baby.
- Who the research was done in matters here. The cramp trials were mostly of magnesium, in pregnancy or in adults with night cramps, and the stomach-upset trial was in children under five in a hospital emergency department; none of these studies was of a hydration tablet taken during sport.
- Reviews of fluid balance describe water tablets (diuretics) as shifting sodium, potassium and chloride in their own right, with potassium and chloride then given deliberately alongside them. In a trial in adults with chronic kidney disease, how far a magnesium supplement lifted the blood level depended on how well the kidneys were working.
If you take medication, are pregnant, or have a health condition, check with a pharmacist or GP first.
The research behind this page (8 studies)
- The Role of Electrolytes in Muscle Pain Syndromes: A Systematic Review and Meta-Analysis With Implications for Temporomandibular Disorder. (2026, meta-analysis)
- Effect of Dilute Apple Juice and Preferred Fluids vs Electrolyte Maintenance Solution on Treatment Failure Among Children With Mild Gastroenteritis: A Randomized Clinical Trial. (2016, randomised trial)
- Electrolyte Imbalances and Metabolic Emergencies in Obesity: Mechanisms and Clinical Implications. (2025, review)
- Electrolyte Imbalance and Neurologic Injury. (2024, review)
- Electrolyte minerals intake and cardiovascular health. (2019, review)
- Unpeeling the Evidence for the Banana Bag: Evidence-Based Recommendations for the Management of Alcohol-Associated Vitamin and Electrolyte Deficiencies in the ICU. (2016, review)
- Potassium intake: the Cinderella electrolyte. (2023, review)
- Water and electrolyte homeostasis during decongestion in heart failure. (2025, review)
How much does electrolytes cost?
That depends on the form and the pack, so we work out the price of the same dose of every electrolytes product we can find and rank them.