Your favorite happy hour drink comes with an unexpected health risk.
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Moscow Mule
Credit: Ryan Moriarty; Styling: Callie Blount

If you’d asked me just a few years ago what a Moscow mule is, my booze-illiterate (and underage) self would not have an answer. But even if you’re just a casual social media peruser, you’ve definitely come across the suddenly ubiquitous cocktail—or, more specifically, the iconic, stylish copper mugs they’re served in—on your Instagram feed.

I’m not exaggerating: They’re. Freaking. Everywhere.

Here’s the not-so-tiny problem with your favorite happy hour trend though. According to the Food and Drug Administration, those copper mugs are not supposed to serve anything acidic, specifically, with a pH below six. (Spoiler alert: Moscow mules are very acidic, according to Iowa’s Alcoholic Beverages Division.)

A refresher on some basic high school chemistry: Coming into prolonged contact with acids can cause uncoated copper to react and leach into your food and drinks, which is definitely not a fun time for your liver or kidneys.

I know, Moscow mules and copper mugs seem like they should be a match made in heaven. But if an FDA Food Code isn’t enough to deter you from trying to achieve perfect #drinkstagram aesthetic, how about these not-so-fun symptoms of excessive copper exposure? Nausea, weakness, fever, and diarrhea are all signs that you need to seek medical help, stat, according to the National Institutes of Health.

Thankfully, according to the NIH, copper poisoning is rare, but we recommend taking precautions. Stick to the safer side and avoid serving this cocktail in those cute copper canisters and instead serve them in highball glasses—with the right garnishes (a lime wedge and a sprig of mint), it’ll be just as photo-worthy, we promise.

Or if you’re absolutely insistent on a traditional Moscow mule look, take the extra time to seek out copper mugs that are lined with a different, non-reactive metal like stainless steel. This will prevent any copper leaching into your beverage, and still lend the authentic Moscow mule vibe to your bar cart, preserving the best of both worlds—good health, and aesthetic. Now go forth, snap those Insta-worthy pictures, lounge by the pool with a cool drink in hand, and sip your Moscow mule without fear of copper toxicity.