Online, #WaterTok has notched a billion-plus views on TikTok in barely a year. Water is seriously trending.

But our hydro-obsession can put us on a slippery slope. Thousands of those #WaterTok videos extol the virtues of water fasting—consuming nothing but flavored water—and powering through a gallon each day. Water influencers (which, yes, are a thing now) flood our feeds with misinformation—Drink eight glasses a day! No, drink an ounce for every pound you weigh!—while bro science—Excessive water consumption flushes out toxins!—surges. The high-water line of H2O’s toxic trendiness may have come late last year, when the actress Brooke Shields turned blue, began frothing at the mouth, and collapsed at a New York restaurant. The culprit? Excess water caused her sodium levels to plummet, leading to a seizure.

“I don’t think people understand: Drinking too much water is not safe and can result in serious complications such as seizures, brain swelling, and even death,” says Robert Glatter, M.D., an assistant professor of emergency medicine at Lenox Hill Hospital who has treated people who’ve landed in the ER due to water fasts. “Most people think more is better, but that’s not true.”