Signs of Electrolyte Imbalance: What to Watch For and When to See a Doctor

Feeling flat in the afternoon, a cramp after a run, a dull headache on a hot day. People often put these down to "low electrolytes", and sometimes they're right. More often the cause is simply not drinking enough.

A true electrolyte imbalance is a medical problem that a doctor diagnoses with a blood test, and it needs medical treatment. This guide explains the difference: the everyday signs that you need to drink more, the warning signs that need a doctor, and where an electrolyte drink does and doesn't fit.

What electrolytes are

Electrolytes are minerals that carry an electrical charge when they dissolve in your body's fluids. The main ones are sodium, potassium, chloride, magnesium, calcium and bicarbonate. Between them they help control where water sits in your body and help your nerves and muscles, including your heart, work normally.

Your kidneys keep these levels within a tight range, and in healthy people they do it very well. Food provides most of what you need, although the World Health Organization notes that most people eat too much sodium and not enough potassium. Good sources include salt in everyday foods, potassium in fruit, vegetables, beans and potatoes, and magnesium in nuts, seeds and wholegrains.

What can throw your levels out

• Vomiting and diarrhoea. The most common cause of a real imbalance, because you lose fluid and minerals fast.
• Heavy sweating. Long or intense exercise, especially in the heat, can mean big sodium losses.
• Some medicines. Diuretics (water tablets) and some blood pressure medicines change how your body handles sodium and potassium.
• Kidney, heart and hormone conditions. These can affect how well your body regulates electrolytes.
• Drinking very large amounts of plain water quickly. This can dilute the sodium in your blood, a condition called hyponatraemia. It's rare, but it does happen in endurance events.
• Heavy drinking. Alcohol makes you pass more urine and can affect several electrolyte levels.

Everyday signs you need to drink more

Most of the time, the "ignored" signs people mean are signs of mild dehydration. The NHS lists these:

• Feeling thirsty
• Dark yellow, strong-smelling pee
• Peeing less often than usual
• Feeling dizzy or light-headed
• Feeling tired
• A dry mouth, lips and eyes

The fix is to drink more fluid. Water is fine. On a hot day, after a sweaty workout or on a long flight, some people prefer a drink with electrolytes in it, partly because a flavoured drink is easier to keep sipping. Pale yellow pee is a good sign you're drinking enough.

Warning signs that need a doctor

These can be signs of a significant electrolyte imbalance or another medical problem. Don't try to treat them with supplements.

• A fast, irregular or pounding heartbeat (heart palpitations)
• Muscle weakness, or cramps and spasms that keep coming back
• Numbness or tingling, especially around the mouth or in the hands and feet
• Confusion, unusual drowsiness or a severe headache
• Vomiting or diarrhoea that won't settle, or not being able to keep fluids down

Speak to your GP or call NHS 111 if you have any of these. Call 999 if someone has chest pain, collapses, has a fit or becomes confused.

Where an electrolyte drink fits

An everyday electrolyte tablet is a convenient way to top up fluid and some minerals when you've been sweating, travelling or just not drinking much. It isn't a treatment for a medical imbalance, and it won't fix cramps or tiredness that have another cause.

If you've had vomiting or diarrhoea, use oral rehydration salts from a pharmacy, as the NHS advises. They're designed for that situation and contain much more sodium than an everyday tablet.

A serving of HIRO electrolyte tablets is two tablets dissolved in about 300ml of water. It provides 300mg potassium, 180mg chloride, 116mg sodium, 65mg magnesium, 2mg zinc and 0.4mg manganese, with 5g carbohydrate and 20 kcal. Potassium contributes to normal muscle function and normal functioning of the nervous system. Magnesium contributes to electrolyte balance and the reduction of tiredness and fatigue.

HIRO is lower in sodium and higher in potassium than most sports drinks, because it's designed for everyday use. For long, hot or very sweaty sessions, a higher-sodium sports drink may suit you better. Our guide to high-potassium electrolyte tablets explains the difference.

If you want to try it, the Multi-Flavour Triple Pack has a tube of each flavour. If you're topping up after a night out, see our guide on hydration tablets and hangovers.

Who should check before using electrolyte products

Speak to your GP or pharmacist first if you have a kidney or heart condition, take medicines that affect potassium or sodium (including some blood pressure medicines and diuretics), are pregnant or breastfeeding, or are an older adult. The NHS advises older people not to take potassium supplements unless a doctor recommends them. HIRO isn't recommended for anyone under 18.

Frequently asked questions

How do I know if my electrolytes are low?

The only reliable way is a blood test arranged by your GP. Everyday tiredness, thirst and headaches are much more likely to be mild dehydration, poor sleep or skipped meals.

Can electrolyte tablets fix an electrolyte imbalance?

No. A diagnosed imbalance needs medical treatment and the cause looking into. Everyday electrolyte tablets are for topping up fluid and minerals in healthy people.

Is it possible to drink too much water?

Yes, though it's rare. Drinking several litres of plain water in a short time can dilute the sodium in your blood. Drink to thirst and spread your fluids through the day.

When are electrolyte drinks most useful?

After long or sweaty exercise, in hot weather, when travelling, or when you find plain water hard to drink enough of. For most people on an ordinary day, water and a balanced diet are enough.