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BOD-ities: Is there such a thing as drinking too much water?

Bryn Mawr Hospital July 6, 2018 BOD-ities By Daniel Wolk, MD

I’ve heard you can die from drinking too much water. Is that true?

Especially in the warm weather months, we’ve been conditioned to hydrate, hydrate, hydrate, by drinking water throughout the day and replenishing with fluids after being in the sun or playing sports. But in rare instances, yes, it’s quite possible to drink yourself to death—with water.

How much is too much water?

According to the American Chemical Society, an example of a water “overdose” would be six liters per 165-pound person. When water is consumed quickly and excessively, it dilutes sodium in the blood. Sodium is an electrolyte that helps maintain a balance of fluids within and outside the cells. An extreme loss of sodium can lead to a condition called hyponatremia, or water intoxication, in which fluid builds up inside the cells causing them to swell. In brain cells, this can be particularly dangerous and life-threatening. If left unchecked, hyponatremia can lead to coma, brain damage, even death.

And because water intoxication symptoms are similar to symptoms of dehydration, such as:

  • Confusion
  • Dizziness
  • Headache
  • Nausea
  • Vomiting

The condition may go unrecognized or the person may be encouraged to drink more fluids, assuming they are dehydrated versus overhydrated.

While it is not something we see very often, water intoxication is a dangerous medical condition. That being said, it’s largely preventable—and treatable—but it’s important to get emergency care before permanent damage is done.

Causes of drinking too much water

There have been a number of highly publicized events in which people have died from drinking too much water. Although it is very difficult to consume that much water that quickly, there are certain people who may be more at risk of rapid overconsumption of water, such as:

  • Marathon runners (or any endurance athletes)
  • Recreational drug use
  • Soldiers engaged in military training
  • People with schizophrenia (thirst is common side effect of certain medications)
  • People with eating disorders

In the case of sports endurance activities, athletes are commonly advised to replenish fluids lost through sweating and physical exertion. A wise approach for runners and anyone gauging their intake of liquid is simply to “drink to thirst” and follow the American College of Sports Medicine guidelines suggested below.

How much water should a person drink in one day?

Water is vital to so many bodily functions, from regulating body temperature to flushing out toxins and waste from our kidneys. For all the fluid we lose each day through perspiration, urination, bowel movements, even breathing, it’s important to replenish—but how much water to drink in one day may be different for everyone. A person who is extremely active, for example, will need more fluid intake than a person who is more sedentary. A person who lives in a hotter climate may need more than a person in a temperate environment. Body size and age matter, too. What’s important to realize is that the body is pretty good at figuring these things out. If the body needs water, you’ll experience thirst. If the body has too much fluid, you’ll pee it out.

Before exercising, be sure to follow the American College of Sports Medicine guidelines, which recommend drinking about 500 milliliters (17 ounces) of fluid about two hours before exercise to promote adequate hydration and allow the body time to eliminate any excess water. During exercise, athletes should start drinking early and at regular intervals with the goal of drinking fluids at the same rate your body is losing water through sweating. For exercise events lasting longer than one hour, consider adding carbohydrates and/or electrolytes to a fluid replacement solution. This will not significantly impair water delivery to the body and it may enhance performance.

There are no evidence-based rules around how many glasses of water you should drink each day.

Outside of these recommendations, there are no rules about how many glasses of water you should drink daily. There is, in fact, no scientific data to support the medical myth of eight 8-ounce glasses of water each day. While water certainly supports health and well-being and is a better choice than sugary drinks like juices and sodas, it has not been proven to help people lose weight, reduce wrinkles, or even make us more energetic. Nor are we walking around dehydrated most of the time, as some might claim.

When it comes to drinking too little or too much, pay attention to your body, but don’t force it. The body is an amazing thing and it will, for the most part, protect itself against dehydration and overhydration.

Main Line Health serves patients at hospitals and health centers throughout the western suburbs of Philadelphia. To schedule an appointment with a specialist at Main Line Health, call 1.866.CALL.MLH (225.5654) or use our secure online appointment request form.