Water is the obvious starting point, but plain water alone isn’t always the fastest or most effective way to rehydrate. The best choice depends on how dehydrated you are. For mild cases, water paired with electrolyte-rich foods or drinks works well. For moderate dehydration, an oral rehydration solution containing a precise balance of salt, sugar, and water outperforms plain water significantly.
Why Plain Water Isn’t Always Enough
When you’re dehydrated, you’ve lost more than just water. You’ve also lost electrolytes, particularly sodium and potassium, which help your body absorb and retain fluid. Drinking plain water replaces the volume but not the electrolytes, so your kidneys end up flushing out a large portion of what you drink before your body can fully use it.
This is where the balance of sugar and salt matters. Glucose (sugar) and sodium travel together across the wall of your small intestine, pulling water along with them. That’s the principle behind every oral rehydration solution on the market: a specific ratio of sugar, salt, and water that maximizes how quickly fluid moves from your gut into your bloodstream.
Oral Rehydration Solutions
Oral rehydration solutions (ORS) are the gold standard for treating mild to moderate dehydration. They’re preferred over IV fluids for several reasons: they’re safer, less painful, less expensive, and just as effective for most people. IV fluids are reserved for severe cases where someone can’t keep fluids down, has a dangerously fast heart rate, or is too confused to drink.
You can buy premade ORS packets or drinks at most pharmacies. The WHO-recommended formula contains about 2.6 grams of salt, 13.5 grams of glucose, 1.5 grams of potassium chloride, and 2.9 grams of trisodium citrate per liter of water. You don’t need to memorize those numbers. Commercial products like Pedialyte, DripDrop, and generic ORS packets are formulated to match these ratios closely.
In a pinch, you can make a basic version at home: mix half a teaspoon of table salt (about 3 grams) and 2 tablespoons of sugar (about 30 grams) into just over 4 cups (roughly 1 liter) of clean water. This recipe comes from WHO guidelines adapted by health services for home use. It won’t contain potassium, so it’s not a perfect substitute, but it works well as an emergency option.
Drinks That Hydrate Better Than Water
Researchers have developed something called a Beverage Hydration Index, which measures how much fluid your body retains two hours after drinking compared to the same amount of plain water. A few drinks consistently outperform water by a wide margin.
Skim milk scores a hydration index of 1.58, meaning your body retains about 58% more fluid than it would from the same amount of water. Full-fat milk is nearly identical at 1.50. Oral rehydration solutions land right in the same range at 1.54. The reason milk works so well is its natural combination of sodium, potassium, and lactose (a sugar), which slows gastric emptying and promotes fluid absorption, much like an ORS does.
Coconut water is another solid option. It’s naturally high in potassium, though lower in sodium than a true ORS. Some evidence suggests it compares favorably to commercial sports drinks for rehydration, and the potassium content may be especially helpful if your dehydration came from sweating or diarrhea. The sodium and potassium levels vary by brand, so check the label if electrolyte content matters to you.
Sports drinks like Gatorade contain electrolytes and sugar but in lower concentrations than an ORS. They’re designed more for preventing dehydration during exercise than for treating it after the fact. They’ll work for mild cases, but if you’re noticeably dehydrated, an ORS or even milk will rehydrate you faster.
Foods That Help You Rehydrate
About 20% of your daily water intake typically comes from food. When you’re dehydrated, eating water-rich produce can supplement what you’re drinking and add electrolytes and minerals at the same time.
The most hydrating foods are almost entirely water by weight:
- Cucumber: 96% water
- Iceberg lettuce: 96% water
- Celery: 95% water
- Radishes: 95% water
- Romaine lettuce: 95% water
Watermelon, strawberries, and oranges are also above 90%. These aren’t a replacement for drinking fluids, but snacking on them while you rehydrate gives your body extra water, potassium, and other minerals that support recovery.
What to Avoid While Dehydrated
Alcohol is a diuretic, meaning it causes your kidneys to produce more urine than the volume of fluid you’re taking in. Drinking alcohol while already dehydrated will make things worse. Coffee and tea have a mild diuretic effect in large amounts, but in moderate quantities they still contribute to hydration overall. If coffee is all you have access to, it’s better than nothing, though water or an electrolyte drink is a smarter choice.
Sugary sodas and fruit juices with very high sugar concentrations can actually slow fluid absorption in your gut. The sugar-to-water ratio matters. ORS formulations keep sugar levels precise for this reason. A glass of apple juice has roughly five times more sugar per liter than an ORS, which can draw water into the intestine rather than out of it, sometimes worsening diarrhea-related dehydration.
Rehydrating Children and Infants
Children dehydrate faster than adults because of their smaller fluid reserves. For a mildly dehydrated child, the general recommendation is about 50 milliliters of ORS per kilogram of body weight, given over four hours. For moderate dehydration, that doubles to 100 milliliters per kilogram. So a 10-kilogram toddler (about 22 pounds) with mild dehydration would need roughly 500 milliliters, or about two cups, sipped steadily over four hours.
If a child has diarrhea, an additional 10 milliliters per kilogram should be given after each loose stool, up to about 240 milliliters (one cup) per episode. Pedialyte and similar pediatric ORS products are formulated for children’s electrolyte needs. Avoid giving young children sports drinks, which have too much sugar and not enough sodium for effective rehydration.
Signs You Need More Than Home Treatment
Most dehydration resolves with oral fluids within a few hours. But severe dehydration, defined as losing 10% or more of your body weight in fluid, requires medical treatment. The warning signs are hard to miss: a rapid pulse paired with low blood pressure, skin that stays “tented” when you pinch it rather than snapping back, dizziness when standing, confusion, or very little urine output over several hours. Red, hot, dry skin combined with a rapid pulse may signal heatstroke, which is a medical emergency.
If you’re vomiting repeatedly and can’t keep any fluids down, oral rehydration won’t work regardless of what you’re drinking. That’s one of the primary situations where IV fluids become necessary. The same applies if dehydration is accompanied by a high fever, bloody diarrhea, or symptoms that have been worsening over 24 hours despite your efforts to drink.