It’s a warm summer day and you’re hanging out with friends and family for the first time in over a year, celebrating being vaccinated and just being together. And to help beat the heat, you reach in the cooler for an ice-cold beer.

While that might be refreshing at the moment, though, there’s good reason to grab some water, too. The heat of summer can be brutal, sometimes, and its effects are amplified when you’ve had a little too much alcohol.

To better understand the risks you face when drinking alcohol during this hot vaccine summer, we spoke with registered dietitian Julia Zumpano, RD.

The biggest danger: dehydration

Whenever you’re outside in the heat for prolonged periods – like at the beach or picnic – you’re at risk of dehydration. Consuming alcohol only heightens that risk.

Alcohol reduces the release of the hormone vasopressin, which keeps your body fluids balanced. At the same time, alcohol is also a diuretic which means more urinating and that can lead to dehydration even without the heat. Add in all that sweat from the hot sun and it’s a recipe for dehydration disaster.

One thing Zumprano points out, too, is that caffeine – whether via coffee, soda or as a mixer for liquor – heightens that dehydration risk even further.

Dehydration can also compound certain aspects of intoxication, she notes. “Altered thinking, altered abilities to drive and make reasonable decisions or even just to have conversations are all things that intoxication can cause.”

Liquor versus beer: Is one worse than the other in the heat?

Given that alcohol content is usually higher in spirits than in your average beer, it makes sense that drinking beer instead of mixed drinks might help you avoid dehydration. But the reality is a little more complex, according to Zumpano.

“If you’re consuming liquor at a volume equivalent to the volume of beer, like 12 ounces of margaritas compared to 12 ounces of an average beer, you will get drunk a lot quicker,” she says. “But if you’re drinking what’s considered an alcoholic drink equivalent, there’s not much of a difference because your alcohol intake is the same.”

According to the National Institute of Health, one alcoholic drink equivalent, also referred to as a “standard drink,” contains around 14 grams of pure alcohol. By those measurements, an average 12-ounce can of beer contains the same amount of alcohol as a 5-ounce glass of wine or a typical shot of distilled spirits like rum, vodka, gin or whiskey.

One thing to keep an eye on, though, is the alcoholic content of your beer. While major brands generally run between 4% and 5% alcohol per 12-ounce can or bottle, certain styles of craft beer are as much as 9% alcohol per the same volume. In other words, one can of your favorite local IPA delivers almost twice the amount of alcohol to your system. 

Beware a false sense of hydration

Another mistake you should avoid, Zumpano says, is thinking that drinking all that liquid rehydrates you. “If you’re drinking a lot of beer or alcoholic seltzer, it can feel like you’re drinking a lot of liquid and staying hydrated, but the alcohol offsets that because it’s the dehydrating factor,” she points out.

Not that drinking mixed drinks is any better, according to Zumpano. “If you’re drinking a sugary, sweet mixed drink, you run into the same thing. It feels like you’re staying hydrated because they go down so much smoother than drinking spirits on the rocks. But it’s the same effect as with beer: The alcohol is still dehydrating you unless you’re also drinking enough water.”

Sugar, the hidden villain

All of these drinks have other adverse health effects, too. They can pack a bunch of calories into a single serving – as many as 400 to 500 calories in some mixed drinks and craft beers – and they can come loaded with carbs.

There’s more, though. “If you’re drinking high sugar, high caloric intake beverages and you’re drinking a lot of them, they can be very filling,” Zumpano says. If you’re feeling full, you might not eat any food which can otherwise help absorb some of the alcohol.

How to counter dehydration: water, water, water

So what can you do to avoid dehydration troubles when you’re sipping your favorite boozy beverage by the pool? “To counteract the dehydration risk of alcohol,” Zumpano says, “drink 8 to 12 ounces of water for every alcoholic drink. It slows your intake, keeps you hydrated and can mitigate negative hangover effects.”

She suggests keeping a reusable water bottle with you that you can refill as the day goes on, taking time to drink the necessary water between beers or margaritas. Another option is to buy a pack of 8-ounce bottles of water and alternate with your booze. And you can always infuse your water with fruit to keep it flavorful.

“It’s also important to know what your trigger for over-consumption is,” she adds. “If you’re triggered by over-consuming beer or alcoholic seltzer, you want to be mindful of that. Try to switch a drink you have better control of and keep the water bottle handy.”