Do You Need Electrolyte Tablets? The Smart, Simple Answer

Most people do not need electrolyte tablets or hydration salts on an ordinary day: food supplies plenty of sodium, and water plus a normal diet keeps most healthy adults well hydrated. They are most relevant for long or hot exercise, heavy sweating at work or in sport, and, in the form of oral rehydration solutions, for fluid loss from vomiting or diarrhoea. The single most useful number on the pack is sodium per serve, and it varies widely between products.

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This guide explains what electrolytes are, how tablets, sachets, sports drinks and oral rehydration solutions differ, how to read the label and work out the sodium in your bottle, who should check with a doctor or pharmacist first, and the mistakes people make with these products. For working out how much fluid to drink after training, see the companion guide to rehydrating after exercise; this one is about the products.

At a glance

• Sodium is the number that matters: compare sodium per serve and per litre, not the marketing on the front.
• Different products do different jobs: oral rehydration solutions are for illness, sports drinks add fuel, tablets and salts add sodium with little or no sugar.
• Daily use is rarely needed: the World Health Organization recommends adults keep sodium below 2,000 mg a day, and many people already eat more.
• Too much plain water is also a risk in very long events. Drinking to thirst is the practical safeguard.
• Talk to your doctor or pharmacist first if you have high blood pressure, heart or kidney disease, or take medicines that affect sodium or potassium.

What electrolytes are

Electrolytes are minerals that carry an electrical charge when dissolved in body fluids. For hydration, the main ones are sodium, potassium and chloride, with smaller roles for magnesium and calcium. Sodium is the main electrolyte outside your cells and largely governs how much water the body holds on to; potassium is the main one inside cells. Your kidneys keep these within a tight range day to day, which is why most people who eat normally and drink to thirst do not need to think about them.

That changes when you lose a lot of fluid and sodium quickly: long or hot exercise, heavy physical work in heat, and illness with vomiting or diarrhoea.

Why sweat losses differ so much between people

Sweat is mostly water with sodium and chloride and small amounts of potassium. A widely cited 2017 review by Baker in the journal Sports Medicine describes sweat sodium concentrations ranging from roughly 10 to 90 millimoles per litre between individuals, and sweat rates from under half a litre to more than two litres an hour depending on the person, the heat and the effort. Two people on the same run can lose very different amounts of salt.

If you regularly finish long sessions with white, gritty marks on your clothes, hat or skin, you are probably a “salty sweater” and may notice more difference from a sodium-containing drink than someone who is not.

The main product types compared

Product type	Sodium level	Sugar	Designed for	Not designed for
Effervescent electrolyte tablets	Usually low to moderate per tablet	Often sugar-free, with sweeteners; some contain sugar	Adding some sodium and flavour to water during or after exercise	Illness with vomiting or diarrhoea
Hydration salts and high-sodium powders or capsules	Moderate to high; some several times higher than tablets	Varies; many low or sugar-free	Heavy sweaters, long events, hot conditions	Everyday desk-based use
Oral rehydration solutions (ORS)	Set by formula; the WHO reduced-osmolarity formula contains 75 mmol/L sodium	Glucose in a set ratio to sodium	Dehydration from vomiting and diarrhoea, under medical guidance where needed	Fuelling exercise
Sports drinks	Usually modest	Contain carbohydrate for fuel	Long or intense sessions where energy matters as well as fluid	Rest days or short sessions
Water plus a meal or salty snack	Depends on the food	Depends on the food	Most everyday rehydration after exercise	Ongoing fluid loss from illness

Oral rehydration solutions work because glucose and sodium are absorbed together in the gut, pulling water with them. That is why their balance is fixed and why they are a medical product first. The WHO and UNICEF reduced-osmolarity formula contains 75 mmol/L each of sodium and glucose, plus potassium, chloride and citrate.

How to read the label

Sodium per serve, and per litre

Labels usually give sodium in milligrams (mg) per tablet or sachet, sometimes also in millimoles (mmol). To convert, 1 mmol of sodium is 23 mg. Because products are made up in different volumes of water, work out the sodium per litre too:

1. Find sodium per serve in mg.
2. Find the volume of water the serve is meant for (for example, 500 ml).
3. Divide the sodium by the volume in litres to get mg per litre (1,000 mg in 0.5 L is 2,000 mg/L).
4. To compare with figures in sports guidance or the ORS formula, divide mg by 23 to get mmol (2,000 mg/L is about 87 mmol/L).
5. To see the salt equivalent, multiply sodium by about 2.5 (1,000 mg of sodium is roughly 2.5 g of salt).

For reference, the American College of Sports Medicine’s fluid replacement position stand (2007) suggests drinks for prolonged exercise containing roughly 20 to 30 mmol/L of sodium, which is about 460 to 690 mg per litre. Some hydration salts sit well above that.

The rest of the panel

• Potassium, magnesium and calcium: usually small amounts. Higher potassium matters for people with kidney disease or on certain medicines.
• Sugar or carbohydrate: useful as fuel in long sessions, unnecessary for a desk day.
• Sweeteners, flavours and colours: check if you prefer to avoid any.
• Caffeine or added extras: some products add caffeine, vitamins or other ingredients; each is a separate decision.
• Independent testing seals: relevant if you compete in drug-tested sport. This guide to supplement certification seals explains what each programme checks.

For the general skills of reading any supplement pack, see how to read a supplement label. Rules on how these products are classified and labelled differ between countries; if you buy from overseas, this guide to buying supplements internationally covers what to check.

When electrolyte products are likely to be useful

Long or hot exercise

Sports nutrition guidance, including the ACSM position stand, generally suggests that plain water is adequate for most sessions under about an hour, and that sodium becomes more useful in longer sessions, in heat, or when sweat losses are large. Sodium in a drink helps you retain the fluid you take in and keeps up the drive to drink.

Rehydrating after heavy sweating

After heavy sweating, drinks containing sodium tend to be retained better than plain water, more of which passes straight through as urine. A meal with some salt, plus water, often does the same job without a special product.

Vomiting and diarrhoea

Here oral rehydration solutions, not sports drinks or hydration salts, are the appropriate choice. Seek medical advice promptly for babies, young children, older adults, anyone who cannot keep fluids down, or anyone with signs of significant dehydration. A pharmacist can advise on suitable products.

When they probably are not needed

For most people on an ordinary day, food supplies plenty of sodium. The World Health Organization recommends adults keep sodium below 2,000 mg a day (about 5 g of salt), and average intakes in many countries are well above that. Adding a high-sodium sachet to every glass of water “for hydration” can push intake higher with no clear benefit. Thirst, urine colour and how you feel are reasonable everyday guides for healthy adults.

Too much water is also a problem

Drinking large volumes of plain water during very long events can dilute blood sodium, a condition called exercise-associated hyponatraemia. It is uncommon but can be serious. The international consensus statement led by Hew-Butler (2015) links it mainly to drinking well beyond thirst, and identifies drinking to thirst as the practical safeguard. Electrolyte products do not make overdrinking safe.

Who should check with a doctor or pharmacist first

• People with high blood pressure, heart failure or kidney disease, or anyone told to limit salt or fluid.
• People taking medicines that affect sodium or potassium, including some blood pressure medicines and diuretics.
• Older adults, whose thirst response can be less reliable and who are more likely to take relevant medicines.
• Anyone pregnant or breastfeeding, or managing a health condition.
• Children: use products made for their age, and follow medical advice for illness.

If any of these apply, talk to your doctor or pharmacist before using electrolyte products regularly.

A five-step checklist before you buy

1. Name the job: long or hot exercise, recovery from heavy sweating, illness, or general use.
2. Match the product type: ORS for illness, sports drink for fuel plus fluid, tablets or salts for sodium without much sugar.
3. Compare sodium per litre using the steps above, and choose a level that fits the job.
4. Check sugar, sweeteners and extras against your needs and preferences.
5. Trial it in training, never for the first time on event day, and mix it at the stated volume.

For how electrolytes fit with other supplements, and the safety points most labels leave out, see the supplements evidence and label guide.

Common mistakes

• Using high-sodium salts every day at a desk. This adds salt without a clear reason.
• Using sports drinks or hydration salts for gastro. Their sodium and sugar balance is not designed for that; an ORS is.
• Making it stronger than the label says. A more concentrated drink is not more effective and can sit heavily in the stomach.
• Comparing per tablet instead of per litre. Products are made up in different volumes, so per-serve figures mislead.
• Overdrinking in long events. Drink to thirst; electrolytes do not make excess fluid safe.
• Ignoring medicines. Some blood pressure medicines and diuretics change how your body handles sodium and potassium.
• Expecting it to fix a hangover. Fluids can help you feel less dry, but they do not speed up how your body processes alcohol.

Sources this guide draws on: Baker LB, Sweating rate and sweat sodium concentration in athletes, Sports Medicine (2017); American College of Sports Medicine, Exercise and Fluid Replacement position stand (2007); World Health Organization and UNICEF reduced-osmolarity oral rehydration salts formulation; World Health Organization guideline on sodium intake for adults and children (2012); Hew-Butler T and colleagues, Statement of the Third International Exercise-Associated Hyponatremia Consensus Development Conference (2015).

Frequently asked questions

Are electrolyte tablets better than sports drinks?

They do different jobs. Most electrolyte tablets provide sodium and some other minerals with little or no carbohydrate, while sports drinks add carbohydrate as fuel for long or intense sessions. For a short gym session, water is usually enough.

Is it okay to drink electrolytes every day?

For most healthy people there is no need, and frequent high-sodium products add salt to an already salty modern diet. On days of heavy sweating, outdoor work in heat or long training, they may make sense. People with blood pressure, heart or kidney conditions should talk to their doctor first.

How do I know if I am a salty sweater?

Common signs are white salt marks on clothing or a hat after long sessions and sweat that stings your eyes. Some sports science services offer sweat testing, but trialling a higher-sodium drink in training is a practical starting point.

Do electrolytes stop muscle cramps?

The evidence is mixed. Fluid and sodium loss may play a part for some heavy sweaters, but muscle fatigue also appears important, and many cramps happen without dehydration. Electrolytes are not a reliable answer to cramping.

Can I make my own electrolyte drink?

A simple homemade sports drink can combine water, a little salt and some juice or sugar. For vomiting or diarrhoea, use a commercial oral rehydration solution instead, because the sodium and glucose balance needs to be right, especially for children.

The bottom line

Electrolyte products are tools for specific situations: long or hot exercise, heavy sweating and, as oral rehydration solutions, illness. They are not a daily necessity for most people. Read the sodium figure first, convert it to per litre, match the product to the job, and check with your doctor or pharmacist if you have a heart, kidney or blood pressure condition.

This article is educational and informational only and is not medical advice. Supplements are not a substitute for a varied diet. Speak to a doctor, pharmacist or accredited dietitian before starting a supplement, particularly if you are pregnant, take medicines or have a health condition.

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