Electrolytes and hydration: when you actually need them

Electrolytes are minerals such as sodium, potassium and magnesium that carry an electrical charge and help your body balance fluids, send nerve signals and make muscles work. For most people, a normal diet and ordinary drinking keep these in balance, and a dedicated electrolyte product is not needed. This guide explains when they genuinely help and how to see past the marketing.

This is general information, not personalised medical advice. If you are unwell, caring for a young child or older person, or have a heart or kidney condition, speak to a pharmacist or doctor.

What are electrolytes and what do they do?

Electrolytes are minerals dissolved in your body's fluids. The main ones are sodium, potassium, magnesium, calcium and chloride. They help control the balance of water inside and outside your cells, support nerve and muscle function — including the heartbeat — and keep your body's chemistry steady.

You get them from everyday food and drink: salt and many processed foods provide sodium; fruit, vegetables and pulses provide potassium; nuts, seeds and greens provide magnesium (covered in our magnesium guide). A balanced diet normally supplies what you need.

Do I actually need an electrolyte drink?

For most people, most of the time, no. If you are reasonably well and active and eating normally, water is enough, and a varied diet replaces what you lose. Despite the marketing, everyday workouts, commutes and warm days generally do not require an electrolyte product.

There are real situations where they help:

• Heavy, prolonged sweating — long or intense exercise, particularly in the heat, where you lose a lot of fluid and salt over time.
• Illness with vomiting or diarrhoea — where you can lose fluid and salts quickly, especially in young children and older adults.

In these cases, replacing salts as well as water makes sense.

When does it matter for exercise?

For shorter or easier sessions, plain water is fine. Electrolytes become more relevant for longer, harder or hotter efforts — often described as activity lasting beyond about an hour — where you sweat heavily and need to replace sodium as well as fluid.

There is also a less obvious point: during very long endurance events, drinking large amounts of plain water without replacing salts can dilute the body's sodium to dangerously low levels (hyponatraemia). For most everyday exercisers this is not a concern, but it is a reason endurance athletes pay attention to electrolytes rather than relying on water alone. If you take creatine, ordinary good hydration is sensible too; see our creatine guide.

What about illness and oral rehydration?

When you have diarrhoea or vomiting, the priority is to keep sipping fluids to avoid dehydration. A pharmacist may suggest an oral rehydration solution — a sachet of salts and sugar you mix with water — particularly for people more at risk of dehydration, such as babies, young children, older adults and those with other health conditions.

Get medical advice if signs of dehydration continue despite rehydration sachets, if vomiting lasts more than a day or two, or if diarrhoea lasts more than about a week. Ordinary sports electrolyte drinks are designed for exercise, not for treating significant dehydration from illness — an oral rehydration solution is the better choice there.

How should I think about sugar and choosing a product?

Many electrolyte and sports drinks contain sugar. A little sugar can help the body absorb fluid and provide energy during prolonged exercise, but for everyday use the added sugar and calories are usually unnecessary. Sugar-free or low-sugar electrolyte products avoid that, though they are still not something most people need day to day.

If you do choose a product, look at the sodium and potassium content and how much sugar it contains, and match it to the situation — endurance exercise and illness recovery have different needs from a normal day.

Can you have too much?

Yes. More electrolytes is not better. Too much sodium is linked to raised blood pressure over time, and most people in the UK already eat more salt than recommended. Taking large amounts of potassium supplements can be harmful, particularly for people with kidney problems or those on certain blood-pressure or heart medicines, because the kidneys control how potassium is cleared. If you have a heart or kidney condition, check with a doctor before using electrolyte products or supplements.

Electrolyte products are not a substitute for a balanced diet, ordinary good hydration, or medical care. For most people, food and water do the job.