Ask Dr. Universe: Your body usually can process extra water, but if it can’t it’s dangerous
Washington State University
Dr. Universe: What happens if we drink too much water? – Joseph, 7, United Kingdom
Dear Joseph,
As an early-rising scientist, I always drink a cup of coffee in the morning. After that, I drink water from a water bottle I keep at my desk.
But what if I drink too much of that thirst-quenching liquid?
I asked my friend Karen Anders if that can happen. She teaches nursing at Washington State University.
She told me that drinking too much water can cause a rare condition called water intoxication.
It’s rare because it doesn’t happen very often. Even if you guzzle lots of water, your kidneys can probably process it. You might feel sloshy and waterlogged. You might throw up, but then you’d just pee the excess water out of your body.
Water intoxication is a serious problem when it happens, though. It mostly happens after drinking an extreme amount of water in a short time – especially if your kidneys aren’t working optimally.
Anders says that it sometimes happens to babies for that reason.
“A baby’s kidneys aren’t quite fully functional yet,” she said. “And they don’t have good signals about thirst. So babies are a little bit more prone to water intoxication.”
That’s one reason grownups watch babies carefully when they’re in the pool or bath. It’s why they must mix the correct amount of water into their formula.
Water intoxication happens because of sodium. You might know it as an element that’s part of the salt you sprinkle on your food. Sodium is an electrolyte. That means it has a charge when it’s dissolved in water.
Your body is mostly water. You can picture your cells floating in electrolyte soup. That soup is water and electrolytes, especially sodium. Your cells use that positively charged sodium to make your muscles move and your nerves work.
If you drink way too much water – too much for your kidneys to remove – that soup will become too watery. There will be much more water than sodium.
To fix that, some of the water will rush into your cells. The soup outside your cells will become less watery. All that extra water will make your cells swell up.
Most of your cells can stretch a little bit with no problem. But your brain cells are stuck inside your hard, bony skull.
“It’s a problem because your brain is in a closed space without a lot of room to adapt to swelling,” Anders said. “So people end up with seizures and neurologic symptoms.”
Those symptoms include having a headache or being confused, dizzy or tired. You might feel sick to your stomach and have muscle cramps.
Water intoxication is a medical emergency. While it’s super rare, it’s good to know what it is, so you can get to a hospital for help.
It’s not something to worry about too much. For the most part, your kidneys know “wet” they’re doing. So you can drink up all the water you want when you’re thirsty.
Sincerely,
Dr. Universe
Adults can help kids submit a question at askdruniverse.wsu.edu/ask.