Can Alcohol Dehydrate You? How and Why

Ever reach for an ice-cold beer to beat the heat on a sizzling summer day? One little twist — fssst! — and refreshment awaits.

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But while that brew may seem like the perfect thirst quencher, knocking it back increases your risk of dehydration. Ditto for drinking a fruity margarita, a crisp rosé or any other alcoholic beverage.

So, why does drinking alcohol dehydrate you? Let’s crack open an answer with the help of registered dietitian Julia Zumpano, RD, LD.

How does alcohol dehydrate you?

Your body knows it needs water, and it’s programmed to conserve fluids to stay hydrated. But drinking alcohol turns down your body’s water-saving signal by reducing the release of a hormone called vasopressin.

This antidiuretic hormone (ADH) tells your kidneys to hold on to water. When alcohol lowers ADH, three things happen:

Your kidneys reabsorb less water to send back into your body.
More water stays in your pee, so your bladder fills faster.
The urge to go hits, and you then head to the restroom to empty out.

“So, even though you’re drinking a liquid, your body may end up with a net loss of water because of the alcohol you’re consuming,” explains Zumpano.

Your body typically starts limiting ADH within about 15 minutes of that first sip of alcohol. (It works quickly!) You’ll probably feel the urge to pee soon after that as urine begins to build up in your bladder.

Factors that increase alcohol’s dehydration effect

Factors that can increase dehydration when drinking alcohol

Alcohol increases dehydration risk on its own, but the effect can be heightened, too, notes Zumpano. Factors that accelerate dehydration include:

Drinking in the heat: When the temperature rises, you sweat more. This increases your body’s overall fluid loss. Add in alcohol, and it’s a double shot of a dehydration driver.
Drinking on an empty stomach: Food slows alcohol absorption. If there’s nothing in your belly, whatever alcohol you drink enters your bloodstream faster. This kickstarts ADH suppression and opens the door to dehydration.
Drinking fast and furious: Quickly chugging a drink (or two) speeds up the dehydration process. Drinking more tends to extend the effects of alcohol that deplete your body’s fluid reserves.

Maintaining proper fluid balance in your body can also be more difficult if you have certain health conditions, like diabetes, kidney disease, liver disease or heart issues. Adding alcohol to the mix can more easily throw hydration levels off kilter.

Do all types of alcohol dehydrate you?

All alcohol — whether it’s beer, wine or a liquor like tequila, vodka or whiskey — is dehydrating, Zumpano emphasizes. But is one of those choices more dehydrating than the others? The answer is more complicated than you might think.

The reason? If you’re dealing with a “standard serving” of each type of alcohol, they all basically hit the same when it comes to dehydration. That’s because each serving is equal in total alcohol content.

But if you pound down more of a boozier drink, you’re going to feel the effects. That’s why liquor, which has a higher alcohol by volume (ABV), can be particularly troublesome when filling glasses.

“If you’re consuming liquor at the same volume as beer — like 12 ounces of a strong margarita compared to 12 ounces of an average beer — you may get dehydrated a lot quicker,” explains Zumpano.

And even within each alcohol category, ABVs can vary widely. Take beer, for example. A simple domestic lager may fall in the 4% to 5% range. A craft IPA, on the other hand, can run 8% or higher.

“Some beers may have twice the amount of alcohol as others,” she cautions. “They don’t hit the same. It’s something to be aware of.”

The effect of drink mixers

While alcohol in a mixed drink is the main driver of dehydration, what else you splash into your glass can also contribute, says Zumpano. You can increase your risk by adding:

Caffeinated products: Like alcohol, caffeine is a diuretic that can make you pee more. So, adding soda or energy drinks to a cocktail can trigger more bathroom visits and dehydration.
Carbonated products: Carbonation can sometimes speed alcohol absorption — so beware the bubbles!
Sweeteners: Syrupy sweet mixers can mask the taste of alcohol, which can lead to you drinking more than you might think. And, as mentioned, more alcohol equals more dehydration risk.

What about nonalcoholic (NA) beer?

NA beers typically contain less than 0.5% ABV. That’s not enough alcohol to trigger the physiological response that starts you down the road toward dehydration, says Zumpano.

“The water in NA beer usually outweighs any alcohol-related fluid loss you might see,” she adds.

How to prevent dehydration from alcohol

So, what can you do to limit your dehydration risk when you’re tipping back alcoholic drinks? Start by following this formula: Drink 12 ounces of water after every alcoholic drink. (One beer, one water.)

“This slows your alcohol intake and helps keep you hydrated,” explains Zumpano. (As a bonus, it can even tamp down potential hangover effects.)

Other recommendations include:

Eating to avoid drinking on an empty stomach
Drinking more slowly (for example, no chugging)
Limiting total consumption
Choosing mixers like soda water or juice over caffeinated or sugary options
Limiting alcohol intake if you’re in warmer temperatures

Bottom line? Don’t make the mistake of thinking alcoholic beverages equal hydration because they’re a fluid. As odd as it may sound, you can get dehydrated from drinking.

“If you’re drinking a lot of beer or alcoholic seltzer, it can feel like you’re taking in a lot of liquid and staying hydrated,” says Zumpano. “But the alcohol offsets that because of the dehydrating factor. Take the steps to stay ahead of any problems.”