Does Soda Actually Dehydrate You More?

December 4, 2025 •

4 min read

According to the CDC, over half of U.S. adults drink at least one sugary beverage, like soda, on any given day. This common habit has led to a widespread health myth that soda can dehydrate you more than it hydrates. But is there truth to this claim, or is it a misunderstanding of how the body processes fluids?

Quick Summary

Despite containing water, soda's high sugar and caffeine content can negatively impact your body's fluid balance. While it won't cause severe dehydration in moderate amounts, it is a poor choice for optimal hydration compared to water or other healthier beverages. The body must work harder to process the added ingredients, which can promote fluid loss and mask true thirst signals.

Key Points

Sodas Contain Water: The myth that soda completely dehydrates you is false; its liquid content does contribute to your body's fluid balance.
Sugar's Dehydrating Effect: The high sugar content requires the body to use water to process and excrete excess glucose, leading to increased urination and cellular fluid loss.
Caffeine is a Mild Diuretic: Many sodas contain caffeine, which increases urine production, though its diuretic effect is mild and transient compared to its water content.
Poor Rehydration Tool: The combination of sugar and caffeine makes soda a less-than-ideal beverage for rehydration, particularly after exercise or when already dehydrated.
Water is the Best Choice: For optimal health and fluid balance, plain water is the superior choice for hydration, as it contains no sugar or caffeine.
Thirst Perception: The taste and carbonation of cold soda can mask your body's natural thirst signals, potentially leading you to consume less water overall.
Healthier Alternatives Exist: Better options for hydration include water infused with fruit, unsweetened iced tea, or sparkling water.

The Science of Soda and Hydration

At its core, soda is mostly water. A 12-ounce can of cola, for instance, is around 93% water by volume. This is why the simple claim that soda dehydrates you is a myth. The liquid content itself does contribute to your overall fluid intake. However, the story becomes more nuanced when you consider soda's other primary ingredients: sugar and caffeine.

The Impact of Sugar

When you consume a sugary drink, your body must manage a sudden spike in blood glucose. Your kidneys respond by filtering out the excess sugar, a process that requires water. This effect can increase urination and, consequently, fluid loss. A high-fructose, sugary beverage has been shown to exacerbate dehydration and renal stress in mildly dehydrated subjects when used for rehydration. The body borrows water from its cells to help process and excrete the extra sugar, leading to a temporary state of cellular dehydration. While not a one-for-one trade where you lose more water than you consume, it makes soda a less-than-ideal fluid for truly rehydrating your system.

The Effect of Caffeine

Many popular sodas contain caffeine, a well-known diuretic. A diuretic is a substance that promotes increased urination, leading to a loss of fluid. The diuretic effect of caffeine has been shown to increase urine production, but in the quantities found in most sodas, this effect is often mild and transient. A 12-ounce cup of coffee has significantly more caffeine than a typical can of soda, meaning the diuretic impact of soda is not as potent as that of coffee. Nonetheless, the combination of caffeine and high sugar content can work against the hydrating benefits of the water in the beverage.

The Thirst-Masking Phenomenon

Another important factor is how soda affects your perception of thirst. Some studies suggest that the cold, fizzy, and sweet nature of soda can provide a deceptive sensation of thirst-quenching. This can lead people to drink less water throughout the day, effectively masking their body's true need for plain water. Choosing soda over water when thirsty can therefore prevent you from properly rehydrating, especially in conditions where you are actively losing fluids through sweat.

Hydrating with Moderation vs. Optimal Hydration

The bottom line is that soda does contribute to your daily fluid intake, but it is far from an optimal choice for hydration, especially during or after physical exertion or prolonged heat exposure. The ingredients that make soda appealing—the sugar and caffeine—are precisely what make it an inefficient rehydration tool compared to water or an electrolyte-rich sports drink. For the average person consuming soda in moderation, the hydrating effect of the water content is not completely negated, but it's a less efficient path to fluid balance.

Practical Alternatives for Better Hydration

Instead of relying on soda, consider these healthier alternatives:

Water with fruit infusions: Add lemon, cucumber, or berries to plain water for a flavor boost without the added sugar or artificial sweeteners.
Unsweetened iced tea: Brew your own tea and chill it for a flavorful, low-calorie alternative.
Seltzer or sparkling water: Satisfies the craving for fizz without the sugar. Seltzer is a better choice than some mineral waters with high sodium content.
Coconut water: Contains natural electrolytes, making it a good choice for replenishing lost minerals after exercise.

A Comparative Look: Soda vs. Water vs. Electrolyte Drink


Feature	Regular Soda	Plain Water	Electrolyte Drink
Primary Hydration Agent	Water	Water	Water, with electrolytes
Sugar Content	Very High	Zero	Moderate to Low
Caffeine	Often Present (Mild Diuretic)	None	None
Electrolytes	Minimal to none	None	High (Sodium, Potassium)
Energy Source	Simple Sugars	None	Carbohydrates (Sugars)
Overall Health Impact	Negative (dental, weight)	Excellent	Good for intense activity
Rehydration Efficiency	Low to Moderate	High	High

Conclusion: Choosing Wisely for Your Health

While the idea that a single soda will dangerously dehydrate you is a myth, the notion that it's a poor hydration choice is grounded in science. The high sugar and, in some cases, caffeine content require extra metabolic effort, leading to fluid shifts and potentially increased urination. This, combined with the way soda can mask your body's natural thirst signals, makes it a suboptimal option for truly replenishing your fluids. For optimal hydration and overall health, plain water remains the undisputed champion. Enjoy soda in moderation as a treat, but don't mistake it for a reliable source of hydration, especially when your body needs it most.

Summary

Drinking soda contributes to fluid intake due to its high water content, but the high sugar and caffeine make it an inefficient rehydrator compared to water. Sugar increases fluid excretion by the kidneys, while caffeine acts as a mild diuretic, counteracting the hydrating effects. The perception of cold and carbonation can also mask your body's true thirst, leading to suboptimal fluid intake. Water or electrolyte drinks are far better choices for maintaining proper fluid balance. Occasional soda consumption does not cause significant dehydration, but it should not be relied upon as a primary hydration source.

Frequently Asked Questions

While soda contains water, relying on it as your sole source of hydration can lead to negative health effects due to its high sugar and caffeine content. It is a very poor substitute for plain water, and overconsumption can strain your kidneys and worsen fluid balance, especially when dehydrated.

The high concentration of sugar in soda draws water from your cells to help process the glucose, which is then excreted by the kidneys. This process increases urination and contributes to cellular fluid loss, making soda a less efficient way to hydrate compared to plain water.

The caffeine content in most sodas is generally low and has only a mild diuretic effect. While it does increase urination slightly, the volume of water in the soda is far greater than the fluid lost from the caffeine's diuretic action. However, it still makes soda less hydrating than a non-caffeinated beverage.

The combination of the cold temperature, carbonation, and high sugar content can create a satisfying, thirst-quenching sensation. However, this feeling is a temporary illusion and can mask your body's underlying need for more substantial hydration, such as plain water.

While diet sodas lack sugar and calories, they are still not the best choice for hydration. They contain artificial sweeteners and no electrolytes, which are crucial for fluid balance, especially when replenishing after exercise. Water remains the superior option.

If you find plain water unappealing, try infusing it with fruits or herbs like lemon, cucumber, or mint. Unsweetened iced tea or sparkling water are also good, flavorful, and hydrating alternatives without the negative effects of soda.

You should prioritize water, especially when you are already dehydrated, such as after sweating heavily from exercise or exposure to heat. Drinking soda in these situations can worsen fluid balance and is less effective than drinking plain water or an electrolyte beverage.