◦ Guide · Hydration
Electrolytes: what they are and what they do
Updated · September, 2026
You drink water all day and still wake up with a dry mouth, a headache or no energy. It isn't always about water — often it's about electrolytes, the minerals that make sure the water you drink actually gets into your cells.
This guide explains what each mineral does, when it's worth replacing them and how to read a label so you don't end up drinking sugar disguised as hydration.
What an electrolyte actually is
An electrolyte is a mineral that, dissolved in water, separates into electrically charged particles. That charge is what lets your body move fluid between compartments, contract muscles and transmit nerve signals.
The main ones in your diet are sodium, potassium, magnesium, chloride and calcium. You lose them mainly through sweat and urine.
What each mineral does
- Sodium: holds fluid where it's needed and is the mineral you lose most through sweat. Without some sodium, a lot of the water you drink heads straight to the toilet.
- Potassium: works inside the cell and balances sodium. It plays a role in muscle contraction and heart rhythm.
- Magnesium: involved in hundreds of enzyme reactions, including muscle relaxation and energy production.
- Chloride: partners with sodium in fluid balance and is part of stomach acid.
- Vitamin C: not an electrolyte, but often added for its antioxidant support and role in immune health.
Signs you might be short on electrolytes
The most common everyday signs are:
- Cramps or muscle twinges, especially at night or at the end of a workout.
- Headaches and brain fog by mid-afternoon.
- Fatigue that feels out of proportion to what you actually did that day.
- Thirst that doesn't go away no matter how much water you drink.
- Very dark or very scarce urine.
If symptoms are intense, persistent, or come with dizziness, palpitations or confusion, that's a doctor visit, not a supplement.
When it's worth replacing them
- Workouts longer than 45–60 minutes, or any workout in heat and humidity.
- Tropical, island climate: in Grand Cayman you sweat all day, boat days included, even without exercising.
- After diarrhoea, vomiting or fever.
- A hangover: alcohol is a diuretic and leaves you short on fluid and minerals.
- Long flights and days spent under heavy air conditioning.
- Intermittent fasting or low-carb diets, which retain less sodium.
How to choose an electrolyte powder
When comparing labels, check four things:
- Added sugar. Many hydration drinks pack 20g or more per serving. If your goal is hydration, not extra calories, look for a formula with no added sugar.
- Real doses. "Magnesium" on the label means nothing if it's a token amount. Check the milligrams per serving.
- A full profile. Sodium and potassium are the base; magnesium is usually what's missing from cheaper formulas.
- Format and convenience. A sachet travels in your bag or dive kit; a tub stays at home. What isn't within reach doesn't get used.
One more thing worth checking wherever you shop: whether the brand is transparent about where and how the product is made.
Electrolytes vs. oral rehydration solution vs. sports drinks
Oral rehydration solution has a ratio of salts and glucose designed for rehydration after significant fluid loss — it's a clinical tool, not a daily drink.
A classic sports drink prioritises carbohydrates for long exercise sessions, which is why it carries sugar.
Sugar-free electrolyte powders focus purely on the mineral side: good for everyday use, training and recovery, without adding calories.
Frequently asked questions
What do electrolytes actually do?
They're electrically charged minerals — sodium, potassium, magnesium, chloride, calcium — that regulate fluid balance inside and outside your cells, muscle contraction and nerve signalling. Without them, plain water doesn't always hydrate you well.
When do I need to replace electrolytes?
When you sweat a lot (long workouts, heat, humid island weather, a day out on the boat), after a bout of diarrhoea or vomiting, after a night of drinking, on long flights, or whenever you go many hours without drinking water.
Do electrolytes have calories?
The minerals themselves carry no calories. What adds calories is the sugar in a lot of sports drinks. A formula with no added sugar contributes essentially zero calories.
Can I take electrolytes every day?
For most healthy people, one daily serving of a sugar-free formula is reasonable, especially if you train or live somewhere hot. If you have high blood pressure, kidney disease or heart disease, check with your doctor first because of the sodium and potassium content.
Is oral rehydration solution the same as a sports drink?
No. Oral rehydration solution is formulated for clinical rehydration after significant fluid loss. A sports drink is designed to replace fluid and energy during exercise, and usually carries a fair amount of sugar.
This guide is general wellness information and does not replace advice from a healthcare professional. If you're pregnant, breastfeeding, taking medication, or have a medical condition, check with your doctor before using supplements.