Electrolytes

What it is

Electrolyte mixes provide minerals — mainly sodium, potassium, chloride, and often magnesium — that help the body hold on to water and keep nerves and muscles working. Some contain sugar, which helps the gut absorb sodium and water.

How it works

Sweat and diarrhea carry away both water and electrolytes, mostly sodium. Replacing sodium helps the body retain the fluid you drink, and pairing sodium with glucose uses a transport system in the gut that pulls water in with them — the principle behind oral rehydration solutions. Potassium and magnesium play roles in muscle and nerve function, though most people's everyday needs are covered by food.

What it's been studied for

Commonly taken to rehydrate during long or hot workouts, heavy sweating, and vomiting or diarrhea.

What the evidence shows

Evidence is strong for oral rehydration solutions, which use a specific balance of sodium and glucose and are a well-established, WHO-recommended way to replace fluids lost to diarrhea. For exercise, replacing sodium makes physiological sense during prolonged, heavy sweating, and sports medicine guidelines support electrolyte-containing drinks in that setting. The key limitation is that for everyday life and short workouts, most people get plenty of electrolytes from food, and there's little evidence that routine electrolyte drinks add benefit.

Who should consider it

People doing long or intense exercise in the heat, heavy sweaters, outdoor workers in hot conditions, and people losing fluids to vomiting or diarrhea are the ones most likely to benefit. People doing ordinary daily activity or workouts under about an hour probably don't need them — water and regular meals are enough. People with kidney disease, heart failure, high blood pressure, or on potassium-affecting medications should check with a provider before using them regularly.

Amounts commonly studied

Reduced-osmolarity oral rehydration solutions are formulated at about 75 mmol/L each of sodium and glucose; sports medicine guidance for prolonged exercise suggests drinks with roughly 20 to 30 mEq/L of sodium and 2 to 5 mEq/L of potassium.

How to take it

During illness, oral rehydration solutions are typically sipped frequently in small amounts, especially if nausea is present. For exercise, electrolyte drinks are most useful during and after sessions lasting more than an hour or involving heavy sweat, with amounts guided by thirst and sweat losses rather than forced drinking. Talk to your provider if you have a chronic condition, take blood pressure or kidney medications, or are caring for a young child or older adult who is sick.

Forms & absorption

Powders, tablets, and ready-to-drink bottles vary widely — true oral rehydration solutions have a specific sodium-to-sugar ratio, while many 'hydration' products have more or less sodium or none. Magnesium in these products may have a mild laxative effect at higher amounts.

Food sources

Sodium: table salt, broth, salted snacks, pickles, and cheese. Potassium: potatoes, bananas, beans, lentils, leafy greens, yogurt, and coconut water. Magnesium: nuts, seeds, legumes, whole grains, and leafy greens.

Safety & interactions

People with kidney disease, heart failure, or high blood pressure should talk to their provider first, since extra sodium and potassium can be harmful. Potassium can build up dangerously when combined with ACE inhibitors, ARBs, potassium-sparing diuretics (such as spironolactone), trimethoprim, or potassium supplements, and diuretics in general change electrolyte balance; magnesium can reduce absorption of some antibiotics and osteoporosis drugs, so space them apart. Signs of severe dehydration — confusion, fainting, very little urine, or an infant or older adult who can't keep fluids down — need medical care, not just a drink mix.

Common questions

Are sports drinks the same as oral rehydration solution?

No. Oral rehydration solutions have a specific balance of sodium and glucose designed for fluid loss from illness, while many sports drinks have more sugar and less sodium. For vomiting or diarrhea, an actual oral rehydration solution is the better match.

Do I need electrolytes if I sweat a lot?

If you're exercising for more than an hour, in the heat, or you finish workouts with salt-crusted clothing, replacing sodium makes sense. For shorter or lighter activity, water and your next meal usually cover it.

Can electrolyte drinks be harmful?

For healthy people in normal amounts, rarely. But people with kidney disease, heart failure, or high blood pressure, or who take medications that raise potassium, can run into real problems and should check with their provider.