Oct 09, 2026

Which Drinks Contain Electrolytes? Milk, Coconut Water and Sachets

A woman in a linen shirt pours milk from a plain carton into a glass at a wooden table, beside a glass of water, a bowl of fruit and a navy jug

Milk, tomato juice, coconut water, pharmacy rehydration sachets, isotonic sports drinks and electrolyte sachets all contain electrolytes, in very different proportions. A 250 ml glass of semi-skimmed milk carries about 108 mg of sodium, 390 mg of potassium and 300 mg of calcium; a glass of coconut water about 500 mg of potassium and well under 200 mg of sodium; a pharmacy rehydration sachet about 300 mg of sodium with glucose; and electrolyte sachets anywhere from about 300 mg to nearly 2 g, depending on whether they are for daily use or heavy sweat.^{1, 2, 3, 4} Which is best depends on what you have lost: glucose plus sodium for a stomach bug, sodium for sweat, and for an ordinary thirsty afternoon, water. This is the drinks spoke of the Wellgard electrolytes guide.

Which drinks contain electrolytes?

Sodium and potassium per typical serving, from the UK composition tables, the published coconut water analysis, the rehydration sachet's product information, the register's definition of a carbohydrate-electrolyte drink and the two labels. No brand is named.^{1, 2, 3, 4, 5}

Drink	Serving	Sodium	Potassium	What else is in it
Semi-skimmed milk	250 ml	108 mg	390 mg	300 mg calcium, 9 g protein, 12 g lactose
Coconut water	250 ml	up to about 190 mg; varies by coconut and carton	about 500 mg	About 2.5 g sugar; little calcium
Orange juice	150 ml	2 mg	240 mg	About 13 g sugar
Tomato juice	150 ml	345 mg	345 mg	Salted in processing
Cola	330 ml	17 mg	3 mg	About 35 g sugar, or sweeteners; caffeine
Black tea or filter coffee	250 ml	trace	up to about 230 mg (coffee)	Caffeine
Squash with a quarter teaspoon of salt per litre	500 ml	about 300 mg	trace	About 26 mmol/L sodium, inside the isotonic band
Isotonic sports drink (carbohydrate-electrolyte solution)	500 ml	230 to 575 mg (20 to 50 mmol/L)	varies, often small	40 to 175 kcal of fast sugar, by definition
Pharmacy oral rehydration sachet	200 ml	about 300 mg (around 60 mmol/L)	about 160 mg	Glucose and citrate; a medicine for diarrhoea
Daily electrolyte sachet (sugar-free)	200 to 500 ml	200 to 500 mg	150 to 300 mg	Often magnesium at 15% NRV or more, some calcium and vitamins
High-sodium sachet for heavy sweat	500 ml	1,000 to 2,000 mg (2.5 to 5 g salt)	300 to 500 mg	Magnesium and calcium at higher levels; check the sugar line

Potassium is easy to drink: milk, coconut water and the juices carry a few hundred milligrams a glass. Sodium is not, unless a drink has been salted on purpose, which is why a litre of fruit juice does nothing for a litre of sweat.

What is the best drink to replace electrolytes?

After vomiting and diarrhoea, the loss is water with sodium, potassium and chloride, and the NHS points anyone with dehydration signs to a pharmacy rehydration sachet; the sachet's glucose is there because it carries sodium and water across the gut wall, which is why rehydration solution is the standard in dehydrating diarrhoea.^{3, 6, 7} In mild cases, 647 minimally dehydrated children did better on half-strength apple juice followed by whatever they would drink than on an electrolyte solution, with treatment failure in 16.7% against 25.0%.⁸ In the beverage hydration index trial, 72 men drank a litre of each of 13 drinks: over four hours a rehydration solution, full-fat milk and skimmed milk left about 300 g less urine than still water, while cola, diet cola, tea, coffee, lager, orange juice, sparkling water and a sports drink were no different from water.¹

Is milk an electrolyte drink?

Functionally, yes, and a good one. Semi-skimmed milk carries 43 mg of sodium, 156 mg of potassium and 120 mg of calcium per 100 ml.² In 11 adults dehydrated by exercise in the heat, low-fat milk, with or without added salt, left them in positive fluid balance five hours later where water and a sports drink did not, with about half the urine output.⁹ It is not a substitute for a rehydration sachet in a child with diarrhoea.⁶

Is coconut water enough?

For potassium, generously; for sodium, usually not. The published analysis puts coconut water at about 51 mEq/L of potassium, roughly 200 mg per 100 ml, and about 33 mEq/L of sodium, roughly 75 mg per 100 ml, varying by palm.⁴ That is close to the inverse of sweat, which runs at about 0.8 g of sodium per litre and comparatively little potassium.¹⁰ In 12 trained men dehydrated by an hour on a treadmill, coconut water, a sports drink and bottled water restored body mass and fluid measures equally, and the coconut water drinkers reported more bloating.⁴ So coconut water is a potassium drink, not a drink for a heavy, salty sweat.

Are sports drinks and electrolyte sachets the same thing?

A carbohydrate-electrolyte solution, the isotonic sports drink, is defined in Great Britain's health claims register as a drink with 80 to 350 kcal per litre from carbohydrate, at least three quarters of it from fast sugars, and 20 to 50 mmol/L of sodium; only those may carry the register's water-absorption and endurance wording.⁵ The glucose drinks sold in corner shops carry about 26 mg of sodium per 100 ml: sugar drinks with a little sodium.² An electrolyte sachet is a food supplement: minerals, usually with vitamins, with or without sugar. A sugar-free sachet carries too little carbohydrate to meet the carbohydrate-electrolyte definition and may not use its wording; what it may say is what its minerals do, and for magnesium at 15% NRV or more that includes that magnesium contributes to electrolyte balance.⁵ Sachets span a wide range, from daily formulas with a few hundred milligrams of sodium to heavy-sweat formulas with nearly 2 g, so the sodium and potassium figures on the label are what to compare.

How do you make an electrolyte drink at home?

A quarter of a teaspoon of table salt is about 1.5 g, which is 600 mg of sodium; stirred into a litre of diluted squash it gives about 26 mmol/L, inside the register's isotonic band, with the squash supplying sugar or sweetener and a splash of orange juice adding potassium.⁵ Half that is the runners' "pinch of salt in the squash", a reasonable sweat drink for an adult. If you use effervescent electrolyte tablets, let them finish fizzing before you drink. What a kitchen cannot make is an oral rehydration solution for a child with diarrhoea: the NHS route for a child with dehydration signs is the pharmacist or 111, not a home recipe or flat cola; rehydration sachets vs electrolyte drinks goes through illness by age.^{6, 7}

Who should not drink electrolyte drinks?

The sodium and potassium set the list. Cutting sodium lowers systolic blood pressure by about 1 mmHg in people with normal blood pressure and nearly 6 mmHg in people with hypertension, so anyone with high blood pressure, heart failure or kidney disease asks a pharmacist or GP before adding salted drinks, and a high-sodium sachet counts towards the NHS 6 g salt maximum.^{11, 12} Potassium is the concern in chronic kidney disease and for anyone on an ACE inhibitor, an angiotensin receptor blocker, spironolactone or amiloride, where high blood potassium is common and can be dangerous.^{13, 14} Rehydration sachets are not for self-treatment in kidney disease or diabetes, and under-twos see a doctor.³ Do you need to drink electrolytes every day? takes the daily-use question in full.

Frequently asked questions

Do electrolytes hydrate you better than water?

The hydration index trial compared a rehydration solution, milk and other drinks with water, not electrolyte sachets: the rehydration solution and milk were retained longer than water, while a sports drink, cola, juice, tea and coffee were not.¹

Can I just put salt in my water?

Yes: a quarter teaspoon in a litre gives about 26 mmol/L of sodium, the same band as an isotonic drink. It replaces sodium only; it is not a rehydration solution for a sick child.^{5, 6}

Which food is highest in electrolytes?

For sodium, cured meats and cheese; for potassium, dried dates (727 mg per 100 g), potatoes (365 mg), bananas (330 mg) and pulses.²

When is the best time to drink electrolytes?

When you are losing them: during and after an hour or more of sweaty exercise, during vomiting and diarrhoea with a pharmacy sachet, or on a day of eating very little.¹⁰

Are electrolytes just salt and water?

Salt is sodium and chloride, two of the seven; potassium, magnesium, calcium, phosphate and bicarbonate make up the rest.¹⁰

Can Muslims drink electrolytes?

The minerals are salts with no animal origin; check flavourings, colours and any capsule ingredients; during Ramadan all fluids, sachets included, are taken between iftar and suhoor.

Sources

Maughan RJ, et al. A randomized trial to assess the potential of different beverages to affect hydration status: development of a beverage hydration index. American Journal of Clinical Nutrition, 2016. PubMed 26702122.
Public Health England. McCance and Widdowson's Composition of Foods Integrated Dataset (CoFID), 2021. gov.uk.
Summary of Product Characteristics for a UK pharmacy oral rehydration sachet, via the MHRA products database. products.mhra.gov.uk.
Kalman DS, et al. Comparison of coconut water and a carbohydrate-electrolyte sport drink on measures of hydration and physical performance in exercise-trained men. Journal of the International Society of Sports Nutrition, 2012. PubMed 22257640.
Department of Health and Social Care. Great Britain nutrition and health claims (NHC) register. gov.uk.
NHS. Diarrhoea and vomiting. nhs.uk/symptoms/diarrhoea-and-vomiting.
Hahn S, Kim Y, Garner P. Reduced osmolarity oral rehydration solution for treating dehydration caused by acute diarrhoea in children. Cochrane Database of Systematic Reviews, 2002. PubMed 11869639.
Freedman SB, et al. Effect of dilute apple juice and preferred fluids vs electrolyte maintenance solution on treatment failure among children with mild gastroenteritis. JAMA, 2016. PubMed 27131100.
Shirreffs SM, Watson P, Maughan RJ. Milk as an effective post-exercise rehydration drink. British Journal of Nutrition, 2007. PubMed 17459189.
Baker LB, et al. Normative data for regional sweat sodium concentration and whole-body sweating rate in athletes. Journal of Sports Sciences, 2016. PubMed 26070030.
Graudal NA, Hubeck-Graudal T, Jurgens G. Effects of low sodium diet versus high sodium diet on blood pressure, renin, aldosterone, catecholamines, cholesterol, and triglyceride. Cochrane Database of Systematic Reviews, 2020. PubMed 33314019.
NHS. Salt in your diet. nhs.uk/live-well/eat-well/food-types/salt-in-your-diet.
Filippini T, et al. Potassium intake and blood pressure: a dose-response meta-analysis of randomized controlled trials. Journal of the American Heart Association, 2020. PubMed 32500831.
Sarnowski A, et al. Hyperkalemia in chronic kidney disease: links, risks and management. International Journal of Nephrology and Renovascular Disease, 2022. PubMed 35942480.

This article is general information, not medical advice. A child with diarrhoea and signs of dehydration needs a pharmacist or 111, not a home-made drink; if you have high blood pressure, heart failure or kidney disease, or take a diuretic, an ACE inhibitor, an angiotensin receptor blocker, spironolactone or amiloride, ask a pharmacist before using salted or potassium-containing drinks.

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