Brooke Shields suffered a seizure after drinking too much water. What you need to know about water toxicity, a potentially fatal condition

The 58-year-old ”Suddenly Susan” star was “drinking so much water” and didn’t realize that her sodium levels were low, she told editor-in-chief Samantha Barry in an article published Wednesday.

“I was waiting for an Uber,” she recalled. “I get down to the bottom of the steps, and I start evidently looking weird, and [the people I was with] were like, ‘Are you okay?’”

She insisted she was fine but soon found herself wandering outside “for no reason at all,” before heading into a restaurant.

At that point, everything went black, she said.

“My hands drop to my side and I go head-first into the wall,” she recounted, adding that she was “frothing at the mouth, totally blue, trying to swallow my tongue.”

The next thing she remembers, she was being loaded into an ambulance, wearing oxygen, with “Bradley f****** Cooper sitting next to me, holding my hand.” Her husband, Chris Henchy, couldn’t be reached, but Cooper happened to be nearby and accompanied her to the hospital.

Shields had “flooded” her system with water, she told the magazine, resulting in low sodium levels. Since then, her doctor has advised her to “eat potato chips every day.”

Too much water can be fatal

It’s unclear if Shields has an underlying condition that predisposes her to low sodium levels. Regardless, water toxicity is a real condition, experts say—one that can prove fatal. This summer a 35-year-old mother from Indiana died of the condition after drinking copious amounts of water—at one point four bottles in less than 30 minutes—after a July 4 weekend of boating that left her severely dehydrated.

Here’s what else you need to know about the condition.

What is water toxicity?

The condition, also known as overhydration, happens when the body takes in more water than it loses, Dr. James L. Lewis III, of Brookwood Baptist Health in Birmingham, Ala., writes in the Merck Manual, routinely referenced by physicians. Because normal kidneys “easily excrete excess water,” it rarely occurs. But those with a disorder that prevents their kidneys from functioning normally—or one that increases their tendency to retain water—are at risk.

So are athletes, “as they tend to drink large amounts of water while simultaneously losing sodium through their sweat,” according to the Harvard School of Public Health. “Women and children are also more susceptible to hyponatremia because of their smaller body size.”

What are symptoms of water toxicity?

According to the Cleveland Clinic, symptoms include:

• Muscle cramps or weakness
• Nausea and vomiting
• Lethargy, or low energy
• Headache
• Mental status changes
• Seizures

How much water should you drink per day?

While the gold standard for many years has been the 8×8 rule, or eight glasses of eight ounces of water per day, the National Academy of Medicine suggests adequate fluid intake is about 125 ounces for men and about 91 ounces for women.

This includes total fluids from fruits and vegetables, water, and other beverages besides water, such as herbal tea, milk, milk alternatives, and smoothies. Sugary drinks and soda should be avoided, however.

Additional reporting by L’Oreal Thompson Payton.