The best thing for dehydration is an oral rehydration solution containing both sodium and a small amount of sugar, not plain water. The combination of salt and glucose triggers a transport mechanism in your small intestine that pulls water into your body far more efficiently than water alone. For mild dehydration, which is the most common type, drinking the right fluid in the right way will resolve symptoms within a few hours.
Why Water Alone Isn’t Enough
Plain water will rehydrate you eventually, but it’s not the fastest or most effective option. Your small intestine has a protein that acts as a two-for-one pump: when sodium and glucose arrive together, it pulls both into your cells and drags water along with them. Research in physiology has shown that roughly 70 to 80 water molecules get swept into the cell alongside each sugar molecule through this pathway. This process works even against the body’s natural osmotic gradient, meaning it actively forces hydration rather than waiting for passive absorption.
This is exactly why the World Health Organization’s oral rehydration solution uses a precise 1:1 ratio of sodium to glucose (75 mmol/L of each). That formula was designed to maximize this pump mechanism. Drinking plain water skips this entirely. Your body still absorbs the water, but more slowly, and your kidneys flush out a larger proportion of it before your tissues get the benefit.
What Works Best: Ranked by Fluid Retention
Researchers use something called the Beverage Hydration Index to measure how well different drinks actually keep fluid in your body over two hours, compared to plain water (scored at 1.0). Anything above 1.0 means your body retains more fluid than it would from the same volume of water.
In a randomized trial published in The American Journal of Clinical Nutrition, beverages with higher sodium concentrations consistently outperformed lower-sodium options. In younger adults, the drink with the highest sodium content scored 1.24, meaning the body retained 24% more fluid than from water. Pedialyte, with 45 mmol/L of sodium, outperformed Gatorade, which contains only 20 mmol/L. The pattern held for older adults too, though their absorption timing differed slightly.
The practical takeaway: commercial oral rehydration drinks like Pedialyte beat sports drinks like Gatorade for actual rehydration. Sports drinks are designed more for energy during exercise (they contain more sugar and less sodium), while rehydration solutions are designed to replace lost fluid and electrolytes. If rapid rehydration is the goal, choose the product with more sodium and less sugar.
How to Make a Rehydration Drink at Home
If you don’t have a commercial product on hand, you can make an effective oral rehydration solution with three ingredients. The WHO-based recipe calls for:
- Water: 4¼ cups (just over 1 liter)
- Salt: ½ teaspoon (3 grams)
- Sugar: 2 tablespoons (30 grams)
Measure carefully. Too much salt can worsen dehydration, and too much sugar pulls water into your intestines in the wrong direction, potentially causing diarrhea. Stir until everything dissolves completely. Store it in the fridge and discard any leftovers after 24 hours.
This solution won’t taste great. It’s not supposed to. The ratio is medicinal, not culinary. If the taste makes it hard to drink, that’s actually a sign you’ve got the proportions about right.
How to Recognize Your Level of Dehydration
Dehydration falls into three categories based on the percentage of body weight you’ve lost as fluid, and each level calls for a different response.
Mild dehydration (under 5% body weight loss) is the most common. You’re alert and responsive, your skin looks normal, and your mouth may feel slightly dry. Thirst, darker urine, and a mild headache are typical. This responds well to oral rehydration at home. Sip steadily rather than gulping large amounts at once, which can trigger nausea.
Moderate dehydration (5 to 9% body weight loss) feels noticeably worse. You may become irritable or sluggish, your heart rate may increase, your breathing gets faster, and your eyes can appear sunken. Your mouth and lips feel distinctly dry, and if you pinch the skin on the back of your hand, it returns to normal more slowly than usual. Both the American Academy of Pediatrics and the WHO recommend trying oral rehydration first even at this stage, but if you can’t keep fluids down or symptoms don’t improve within a couple of hours, you likely need IV fluids.
Severe dehydration (10% or more body weight loss) is a medical emergency. Signs include confusion or reduced consciousness, a rapid and weak pulse, cold or blotchy hands and feet, pale or mottled skin, deep rapid breathing, and very dry, wrinkled skin. This level of dehydration cannot be treated at home.
Rehydrating Children
Children dehydrate faster than adults because they have a higher ratio of surface area to body weight, and they often can’t communicate what they’re feeling until symptoms are more advanced. Watch for dry lips and tongue, fewer wet diapers, crying without tears, and unusual fussiness or sleepiness.
Oral rehydration solutions work well for kids. Studies show that fewer than 5% of children treated with oral rehydration end up needing IV fluids. For infants and toddlers, offer small, frequent sips rather than full cups. A teaspoon every few minutes is a good starting point, gradually increasing as they tolerate it. Avoid fruit juice, which contains too much sugar and not enough sodium, and can make diarrhea worse.
Common Causes and How They Change the Approach
The cause of your dehydration affects what you lose and how you should replace it. Vomiting and diarrhea strip sodium and potassium along with water, making electrolyte replacement critical. A rehydration solution is clearly the right choice here. If you’re vomiting, wait 15 to 20 minutes after an episode before trying small sips.
Sweating from exercise or heat primarily loses water and sodium, but in lower concentrations than diarrhea. A hypotonic drink (one with lower solute concentrations than your blood) absorbs faster and works well when the primary goal is replacing water rather than calories. For prolonged exercise lasting more than an hour, adding some sodium matters more than adding sugar.
Fever, even without vomiting or diarrhea, increases fluid loss through faster breathing and sweating. The fluid needs aren’t as dramatic, but steady sipping of a rehydration solution helps, especially in children.
How Quickly Rehydration Works
With mild dehydration and a proper oral rehydration solution, most people feel noticeably better within one to two hours. Full rehydration of your tissues, including your brain and muscles, takes longer. Plan on steady fluid intake over four to six hours for mild cases and up to 24 hours for moderate dehydration.
Your urine color is the simplest way to track progress. Dark amber means you’re still dehydrated. Pale yellow means you’re approaching normal hydration. Completely clear urine means you’re drinking more than you need, and your kidneys are just flushing the excess.