Drinking Too Much Water Can Be Just as Dangerous as Dehydration. Here's What to Know

Fit young Woman in black sportswear drinking water from a reusable metal bottle after running workout: can you drink too much water?
Getty Images | Jordi Salas
Getty Images | Jordi Salas

"Make sure to drink a lot of water" — you've heard it from your parents, coaches, doctors, and friends. It's not bad advice either, considering that 75 percent of Americans are chronically dehydrated, according to recent research. But is it possible to drink too much water?

Unfortunately, yes. And it can have dire consequences. Hyponatremia (also known as water intoxication or water poisoning) can occur if you drink too much water in a short period of time, and in severe cases, it can result in death. With extreme heat waves hitting the entire country this summer — and headlines circulating about people experiencing heat exhaustion or heat stroke — your first instinct may be to grab your water bottle and chug, but there are serious risks involved with drinking too much water.

We asked a dietitian for the facts about how much you should be drinking, what happens if you drink too much water, and what symptoms to look out for that might signify you've had too much water.

What Happens If You Drink Too Much Water?

If you drink too much water in a short period of time, it can cause something called water intoxication. Water intoxication occurs because drinking an abnormally large amount of water flushes the system and causes sodium levels in the bloodstream to drop to a dangerously low level, explains Liz Weinandy, MPH, RD, registered dietitian at the Ohio State University Wexner Medical Center. The body needs adequate sodium to regulate blood pressure as well as a number of important functions, such as muscle contraction. Hyponatremia, the name for this condition, according to the National Library of Medicine, is extremely dangerous and can lead to unconsciousness, coma, and ultimately death.

Symptoms of Drinking Too Much Water

Getting to a state of hyponatremia is difficult, Weinandy says. To reach the point of water intoxication, "a person would be drinking so much fluid that they would feel nauseous and they might vomit," she said. Other symptoms include headache and lethargy, confusion, or even restlessness and irritability, according to the Mayo Clinic.

Feeling sick while drinking too much water is part of the body's system of checks and balances, which works to prevent us from unknowingly harming ourselves, she said. "The thirst mechanism will kick in when our body needs more fluids, and when we've had enough or a little bit more than enough, the mechanism that makes us repel against drinking anymore will also kick in." Always listen to your body and don't force yourself to drink more water if doing so is making you feel ill.

The Mayo Clinic recommends seeking emergency care for anyone who develops severe symptoms of hyponatremia, including nausea and vomiting, confusion, seizures, or loss of consciousness. If you know you're at risk of hyponatremia and are experiencing mild symptoms, such as nausea, headaches, cramping, or weakness, Mayo Clinic recommends calling your doctor.

How Much Water Can You Safely Drink?

There's no universal cutoff for how much water you can drink before it becomes unhealthy. The limit for each individual person depends on gender, age, activity level, and more, Weinandy says. You may be at an increased risk of water intoxication if you have a medical condition, are on certain medications (such as diuretics, antidepressants, or pain medications), or doing intense physical activities (such as running long distances), according to the Mayo Clinic.

Staying in tune with your body's signals is key to avoiding overhydration, Weinandy says. Check the color of your pee: If your urine is nearly clear, you're adequately hydrated and don't need to drink more, she says.

Pacing yourself while drinking water will also help keep the body in balance. Hydrate before, during, and after a sporting event to avoid fluid overload following exercise. For athletes who are losing a lot of electrolytes through sweat, it's important to throw a sports drink into the mix. This will help replace necessary electrolytes such as sodium and potassium, Weinandy says.

In cases of extreme thirst, call your doctor before an excessive amount of water that could put you at risk for hyponatremia.

How Much Water to Drink Per Day

The amount of water you need to stay properly hydrated also depends on gender, age, and activity level, Weinandy says — but eight glasses a day is a reasonable goal, per the Mayo Clinic.

Rather than following strict guidelines, though, Weinandy recommends listening to your body. "I always tell people you should be drinking enough fluid to where your urine is really pale colored," she says. "Aim for straw-colored or lighter."