Too much of any Instagram trend can be a bad thing. Too many Knoll Wassily chairs and wavy mirrors can make an apartment look cluttered; too much of a trendy moisturizer can overwhelm your pores; and, yes, it’s possible to drink too much water.

Giant water bottles have exploded on social media, with influencers often espousing how they’re in “water-drinking competitions” with friends or that their new goal is to drink multiple gallons per day. Which sounds great, honestly. Out of every nebulous wellness trend, “drinking enough water” feels more common sense than taking a new supplement each week or downing celery juice. Water is … water. No one can debate that, and plenty of people don’t drink enough of it. But overhydration—a.k.a. drinking too much water—is a real concern with real consequences.

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“Overhydration is essentially ingesting more water than your body is capable of getting rid of,” says James Gladstone, chief of sports medicine and associate professor of orthopedic surgery at Mount Sinai Health System. “Depending on your degree of overhydration, it can affect you in different ways. The symptoms initially are typically quite mild. You may have a headache, you can get nauseous, and as overhydration becomes more severe, you may get mental status changes.” Severe overhydration cases can lead to seizures, muscle cramps, and fainting, he adds.

These effects are typically due to “diluting the sodium in your system,” says Gladstone, though he stresses that overhydration is rare. It sounds silly, but the more water you drink, the more sodium your body needs to survive (it’s an essential mineral). “The body has an incredibly good system to dispose of water via the kidneys and urination before it gets to the point of being dangerous,” he says.

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But if you’re suddenly downing gallon after gallon of water because of a TikTok? Then, yeah, you need to think carefully about this. “Symptoms develop progressively,” Gladstone explains. “Mild overhydration can typically be treated by reducing your water intake. However, if the overhydration overwhelms your body, you’ll then begin developing the symptoms mentioned above. If you’ve been training hard and drinking an excessive amount of water and start developing a headache, lightheadedness, nausea, or an inability to think clearly, then overhydration should be in the differential diagnosis.”

Oh, if you’re wondering how much water you should actually be drinking every day: “There are many different calculations out there. However, on average, a healthy adult should consider drinking up to 100 ounces of water a day,” says Gladstone. That’s a little less than three liters, or .78 gallons. Totally doable, if you ask us.

This article originally appeared on Harper’s BAZAAR US.

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