Too Much of a Good Thing: The Danger of Over-Hydration

The saying "you can have too much of a good thing" even applies to water. Learn about the dangers of over-hydration and hyponatremia.


Planning on guzzling H2O to stay hydrated during practice this summer? Turns out dehydration isn't the only thing you have to worry about. The saying "you can have too much of a good thing" even applies to water.

It sounds crazy, right? Especially when you consider that constantly chugging water is practically ingrained in athletes since their first peewee game. But over-hydration or water intoxication is just as real and serious as dehydration.

Over-hydration and hyponatremia

Simply taking in more water prior to intense exercise or activity can overhydrate you. This is why you should stay hydrated throughout the day—not try to overcompensate by chuggling a few bottles before a workout. (Learn how to How to Schedule Your Hydration.)

Sometimes over-hydration causes no symptoms. Other times it can cause headaches, confusion and feelings similar to intoxication. (Watch this Gatorade Sports Science Institute video for more information.)

Severe over-hydration can lead to the condition known as hyponatremia. This is a fluid-electrolyte imbalance that occurs with athletes whose sodium levels are abnormally low. When these athletes take in an excess of water, it causes their bodies' water levels to rise, making their cells swell up. This swelling can cause a multitude of health problems, ranging from mild to fatal. (For the full list click here.)

This is why it is so important for athletes to keep their electrolyte levels in check—particularly sodium, the primary and most important electrolyte lost in sweat. (Ask the Experts: Why Are Electrolytes Important?) Drinking water actually dilutes the level of sodium in the bloodstream.

Hyponatremia is rare but it's most prevalent in athletes, especially endurance athletes, who need more sodium and fluids than the average population.

Who's at risk?

  • Athletes who drink too much before and during prolonged exercise in the heat and humidity
  • Dehydrated athletes who overcompensate before a workout by overconsuming water
  • Athletes who only consume water before long workouts or races
  • Smaller athletes prone to excessive sweating

Water: How much is too much?

Don't let the scare of overhydrating stop you from actually drinking enough to stay hydrated. According to Merck, an athlete with normal kidney function would have to regularly drink over six gallons of water a day. Athletes, especially youth athletes, are more likely to not drink enough for their activity level. This is why dehydration is still more common among athletes, particularly in the hot summer months. Remember just a 2% dehydration level in the body can cause a 10% decrease in performance. (How can you tell if you're dehydrated? See the chart in this article: Hydrating before volleyball matches.)

The most common cause of dehydration is when athletes don't drink enough throughout the day or during their workouts. But it can also occur when an athlete simply sweats out more fluid than he or she can replenish—the complete opposite scenario of over hydration.

Avoiding over-hydration and dehydration 

Luckily you can prevent both of these extremes by knowing the key components of proper hydration. That is, knowing how, what and when to drink. (Review it all here: Time Your Fueling for Peak Performance.)

  • Throughout the day, regularly sip water and other low-calorie beverages to maintain hydration. Athletes who suffer from muscle cramps might consider a low-sugar, electrolyte-rich beverage like Gatorade's G2. This type of beverage provides the electrolytes needed to hydrate an athlete without additional sugar.
  • Adequately hydrate before activity by drinking 16 to 20 oz. of water or a sports drink with a pre-activity meal two to four hours before. If you're practicing or playing in hot and humid conditions, consider drinking a little more between the pre-workout meal and the workout.
  • Approximately 30 minutes prior to the workout, drink another five to 10 oz.
  • During activity, consume five to 10 oz. of water or sports drink every 15 to 20 minutes.
  • Following activity, the goal is rehydration. Consume 16 to 24 oz. for every pound lost. If you're in two-a-day workouts or need to perform again soon, drink 24 oz. for every pound lost to help with rapid rehydration.
  • Remember water does not contain the electrolytes lost in sweat. Drinking a sports drink containing sodium and potassium (like Gatorade) or consuming sodium and potassium-rich foods is essential to rehydrate properly.
  • Sodium-rich foods are salty foods like pretzels, crackers, popcorn, soup, pickles, tomato sauce, deli meat and beef jerky.
  • Potassium-rich foods include bananas, strawberries, potatoes, sweet potatoes, avocado, coconut water and other fruits and vegetables.
  • Eating foods full of electrolytes and drinking proper amounts of water is another way to hydrate. So whether you grab a sports drink or beef jerky, or a banana and water, make sure you get those electrolytes in.


Adrogué, H.J., and N.E. Madias (2000). Hyponatremia. New Engl. J. Med. 342:1581-1589.

American Dietetic Association, Dietitians of Canada, and American College of Sports Medicine (2000). Nutrition and athletic performance. J. Amer. Diet. Assoc. 100:1543-1556.


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