Water works for mild dehydration, but it’s not actually the most efficient option. Drinks that contain small amounts of sodium, sugar, and potassium are absorbed faster and retained longer than plain water. The best choice depends on how dehydrated you are and what you have available.
Why Plain Water Isn’t the Best Option
Water hydrates you, but your body doesn’t hold onto it as well as you might expect. When you drink a large amount of plain water, your blood becomes diluted relative to the fluid inside your cells, and your kidneys respond by flushing out the excess. You end up urinating a significant portion of what you drank within two hours.
Drinks that contain electrolytes, particularly sodium, signal your body to retain more fluid. Sodium also activates a transport system in your small intestine that pulls water into your bloodstream more efficiently, especially when a small amount of sugar is present alongside it. This is the principle behind oral rehydration solutions, which score about 20% higher than water on hydration efficiency indexes.
Best Drinks for Rehydration, Ranked
Not all beverages hydrate equally. Here’s what performs best based on how much fluid your body actually retains:
- Oral rehydration solutions (ORS): Products like Pedialyte and DripDrop are specifically designed to match the sodium-glucose ratio that maximizes absorption. They’re the gold standard for moderate dehydration, especially from illness.
- Milk: Both whole and skim milk outperform water for hydration. The combination of protein, fat, natural sugars, and electrolytes (sodium and potassium) slows gastric emptying, meaning fluid stays in your system longer. Milk’s hydration efficiency is comparable to an oral rehydration solution.
- Coconut water: Naturally high in potassium with moderate sodium, coconut water rehydrates just as effectively as commercial sports drinks. In a study of exercise-trained men who lost about 2% of their body weight through sweat, coconut water restored hydration and exercise performance equally well compared to a standard sports drink.
- Sports drinks: Gatorade, Powerade, and similar products contain sodium and sugar in concentrations that help with absorption. They’re designed for sweat losses during exercise rather than illness-related dehydration, so they have less sodium than ORS but more than water.
- Water: Still effective, just not optimal. If mild dehydration is your only concern and you’re eating regular meals (which supply sodium), water is perfectly adequate.
How to Make a Rehydration Drink at Home
If you don’t have a commercial rehydration solution on hand, the World Health Organization’s recipe is simple: combine 4¼ cups of water with ½ teaspoon of salt and 2 tablespoons of sugar. Stir until dissolved. That’s it.
For a version with added potassium, use ½ teaspoon salt, ¼ teaspoon salt substitute (like No Salt, which is potassium chloride), ½ teaspoon baking soda, and 2 tablespoons sugar in 4 cups of water. The measurements matter here. Too much sugar actually works against you, and too much salt can be dangerous, especially for children. Stick to the recipe precisely.
Drinks That Make Dehydration Worse
Beverages with high sugar concentrations can pull water into your intestines rather than absorbing it into your bloodstream. When the sugar content exceeds roughly 8%, the drink becomes more concentrated than your body’s own fluids, which can trigger loose stools and worsen fluid loss. Fruit juices, regular soda, and energy drinks all fall into this category. Apple juice, for example, contains about 11% sugar. If you want to drink juice while dehydrated, dilute it with at least an equal part water.
Alcohol is a diuretic that increases urine output and should be avoided entirely when you’re dehydrated. Coffee in moderate amounts (a cup or two) is less of an issue than people assume, since the fluid content partially offsets the mild diuretic effect, but it’s not a rehydration tool.
How Fast to Drink
Sipping steadily over 15 to 30 minutes is more effective than gulping a large volume at once. Your small intestine can only absorb so much fluid at a time, and drinking too fast can cause nausea or trigger your kidneys to dump the excess. If you’re rehydrating after exercise, aim to drink about 1.5 times the amount of fluid you lost. A simple way to estimate this: weigh yourself before and after activity, and drink about 24 ounces for every pound lost.
If you’re rehydrating because of vomiting or diarrhea, start with small sips, as little as a teaspoon every few minutes, and gradually increase as your stomach tolerates it. Using an ORS rather than plain water is especially important here, because diarrhea and vomiting deplete sodium and potassium along with fluid.
When Drinking Isn’t Enough
Oral rehydration works for mild to moderate dehydration. Signs that you’ve crossed into severe territory include extreme fatigue, confusion or unresponsiveness, very dark urine or no urine output for many hours, rapid heartbeat, and dizziness when standing. In children, watch for no tears when crying, a sunken soft spot on an infant’s head, or unusual drowsiness. Severe dehydration requires intravenous fluids in an emergency setting, because the gut can’t absorb fluid fast enough to correct it.