What is the most hydrating drink when dehydrated? The surprising truth.

November 12, 2025 •

5 min read

According to a 2016 study published in the American Journal of Clinical Nutrition, skim milk was found to be more hydrating than plain water for a sustained period. So, what is the most hydrating drink when dehydrated? The answer depends on the cause and severity of your fluid loss.

Quick Summary

This article explores various beverages and their effectiveness for rehydration, analyzing the science behind how certain drinks are absorbed by the body. It covers the benefits of milk, oral rehydration solutions, and water, along with discussing suitable options for different situations like illness or intense exercise.

Key Points

Beyond water: For reversing dehydration, beverages containing a balance of electrolytes, protein, or sugar can be more effective than plain water for sustained fluid retention.
Milk's hydrating power: Skim milk is a surprisingly effective rehydration beverage due to its electrolytes, protein, and natural sugars, which slow stomach emptying and help the body retain fluid for longer periods.
ORS for illness: For dehydration caused by vomiting or diarrhea, Oral Rehydration Solutions (ORS) are medically recommended, as they contain a precise electrolyte and glucose ratio for rapid fluid absorption.
Exercise needs: While sports drinks are marketed for hydration, they are best suited for intense or prolonged exercise. For most situations, less-sugary alternatives like coconut water are healthier options.
Foods aid hydration: High-water-content foods such as fruits, vegetables, and broths contribute significantly to overall fluid intake and can help replenish lost electrolytes.
Avoid sugary diuretics: High-sugar sodas and alcohol can inhibit effective rehydration and should be avoided, as they can actually increase fluid loss.

Beyond Water: The Science of Hydration

When it comes to rehydration, not all liquids are created equal. While water is essential for daily fluid intake, research indicates that certain beverages can be more effective for recovering from dehydration. The effectiveness hinges on a drink's nutrient composition, including its balance of electrolytes, sugar, and protein, which influences how quickly and efficiently the body can absorb and retain fluid. This is measured by the Beverage Hydration Index (BHI), which compares a drink's fluid retention to that of plain water.

Electrolytes, such as sodium and potassium, are minerals vital for maintaining the body's fluid balance. When you become dehydrated, especially through heavy sweating or illness, you lose more than just water; you lose critical electrolytes. A drink that replaces both fluid and these essential minerals is often superior for recovery compared to water alone, which can dilute existing electrolytes if consumed rapidly.

The Top Contenders for Optimal Rehydration

Based on scientific studies and expert recommendations, several drinks stand out for their hydrating properties. Understanding the benefits of each can help you choose the best option for your specific situation.

Milk: A Surprising Winner

Studies, including the BHI research from St. Andrews University, consistently rank milk as more hydrating than plain water. The reason lies in its composition. Milk contains a natural blend of lactose (sugar), protein, and fat, which slows down the emptying of the stomach. This slower digestion means the body absorbs the fluids over a longer period, leading to less urine production and better overall fluid retention. Milk also naturally contains sodium, which acts like a sponge to help the body hold onto water. This makes it an excellent choice for rehydrating after exercise or for general recovery.

Oral Rehydration Solutions (ORS)

For moderate dehydration, particularly caused by vomiting or diarrhea, oral rehydration solutions are a top recommendation. These specially formulated drinks, like Pedialyte, contain a precise balance of water, glucose, and electrolytes (sodium and potassium). This combination is designed to maximize the body's ability to absorb fluid in the small intestine, providing rapid and effective rehydration. For severe cases, a hospital-administered IV might be necessary, but ORS are often the best at-home treatment. You can even make a simple ORS at home with water, sugar, and salt.

Coconut Water

Often touted as a natural sports drink, coconut water is rich in potassium, calcium, and magnesium. It is naturally low in sugar and can be a good source of electrolytes for mild to moderate fluid loss. While some studies suggest its rehydrating effects are comparable to plain water, others note its high potassium content can be beneficial for replenishing lost minerals. It offers a healthier alternative to sugary sports drinks for many situations.

Sports Drinks

For high-intensity or prolonged exercise (lasting over an hour) where fluid and electrolyte loss is significant, commercial sports drinks like Gatorade can be beneficial. They contain carbohydrates for energy and a balance of electrolytes to aid in fluid absorption. However, for most people and general dehydration, the high sugar and calorie content can be a drawback. It's important to choose wisely and check labels for added sugar.

Hydrating Foods and DIY Remedies

Beyond beverages, many foods are excellent sources of hydration due to their high water content and natural electrolytes. Incorporating these into your diet can support your overall fluid balance.

Hydrating Foods Include:

Fruits: Watermelon, strawberries, oranges, and grapes.
Vegetables: Lettuce, cucumber, spinach, and tomatoes.
Soups: Broth-based soups provide fluid and electrolytes like sodium.
Dairy: Yogurt and cottage cheese contain fluids and minerals.
Salty Snacks: Pretzels and crackers, consumed with water, can help replace lost sodium.

For a homemade electrolyte drink, you can combine a few common ingredients:

1 liter of water
6 teaspoons of sugar
½ teaspoon of salt Mix until dissolved and sip slowly to aid rehydration.

Beverage Comparison for Rehydration

Here is a table comparing several drinks based on their rehydration properties, according to research like the Beverage Hydration Index (BHI) where still water is the baseline (1.0).


Beverage	Hydration Potential	Key Nutrients	Best For	Considerations
Skim Milk	High (BHI approx. 1.58)	Electrolytes, Protein, Carbohydrates	After exercise, moderate dehydration	Not suitable for lactose intolerance or diarrhea
Oral Rehydration Solution (ORS)	High (BHI approx. 1.54)	Electrolytes (Na, K, Cl), Glucose	Illness (diarrhea, vomiting), moderate dehydration	Effective but can be high in sugar in some versions
Coconut Water	Moderate	Potassium, Sodium, Magnesium	After exercise, mild dehydration	Can be low in sodium for intense sweat loss
Orange Juice	Moderate (BHI approx. 1.39)	Water, Potassium, Vitamin C	Quick fluid and nutrient boost	High in sugar; can worsen diarrhea
Still Water	Baseline (BHI approx. 1.0)	Pure fluid	Everyday hydration, mild dehydration	Doesn't replace electrolytes lost from heavy sweating
Sports Drink	Moderate-Low (BHI similar to water)	Electrolytes, Sugar	Intense or prolonged exercise	Often high in sugar and artificial ingredients

What to Avoid When Dehydrated

Certain drinks can actually worsen dehydration due to their diuretic effect or high sugar content. Alcohol, for instance, acts as a diuretic, increasing fluid loss through urine. High-sugar beverages like soda and concentrated fruit juices can also be counterproductive. The high sugar content draws water into the intestines to be diluted, which can delay fluid absorption. For children with illness, sugary drinks are particularly discouraged as they can worsen diarrhea.

Conclusion: Making the Right Choice

While plain water is the cornerstone of daily hydration, it is not always the most effective drink for reversing dehydration. The best choice depends on the specific cause and severity. For moderate dehydration due to illness or intense exercise, a beverage containing a balanced mix of electrolytes, and sometimes carbohydrates, is ideal. Skim milk and Oral Rehydration Solutions top the list for their superior ability to aid fluid retention. For mild dehydration or general maintenance, water is perfectly sufficient. By understanding the science behind different drinks, you can make an informed decision to rehydrate quickly and effectively. For further reading on this topic, consider exploring the research published in the American Journal of Clinical Nutrition regarding the beverage hydration index.

Ultimately, listening to your body and addressing fluid loss promptly is key. For severe dehydration, especially if accompanied by rapid heart rate, confusion, or dizziness, seek immediate medical attention.

Frequently Asked Questions

Milk is more hydrating than water for a sustained period because it contains natural sugars, protein, fat, and electrolytes like sodium and potassium. These components slow down the emptying of the stomach, allowing for a slower, more gradual absorption of fluids by the body.

For most everyday activities and mild dehydration, water is sufficient. However, for intense or prolonged exercise (over 60 minutes) where significant sweat and electrolyte loss occurs, a sports drink can be beneficial to replenish lost minerals and carbohydrates.

For dehydration from illness, an Oral Rehydration Solution (ORS) is the best option. These solutions have a specific balance of electrolytes and glucose designed for rapid and efficient absorption, which can be more effective than plain water.

Yes, highly sugary drinks like soda or concentrated fruit juices can be counterproductive when dehydrated. The high sugar content can pull water from your body into your intestines, delaying effective rehydration and potentially worsening symptoms like diarrhea.

Yes, about 20% of your daily fluid intake comes from food. Many fruits and vegetables, such as watermelon, strawberries, and cucumber, have a high water content and can contribute to your hydration, along with providing important electrolytes.

Coconut water is a good source of potassium and other electrolytes, making it a healthy choice for mild to moderate dehydration. It's often lower in sugar than many sports drinks and can be a good natural rehydration option.

Signs of severe dehydration include rapid heartbeat, dizziness, confusion, or not urinating. If you experience these symptoms, especially if you can't keep liquids down, you should seek medical attention, as intravenous (IV) fluids may be necessary.