Water Intoxication: Did You Know That Overhydration Can Be Deadly?

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From the counterintuitive department: New guidelines reveal the health risks of drinking too many fluids while exercising.

Of all the health advice we are constantly bombarded with in the media (confession: I’m guilty of bombarding) to drink plenty of fluids is a constant. Water, it would seem, solves all that ails from wrinkles to wellness and everything in-between. And yes, we are creatures made up of up to 60 percent water and getting enough is essential for survival. But as it turns out, even with water, too much of a good thing can be too much.

While the risks of not getting enough water are well known, the dangers of getting too much water are not. Now, a set of international guidelines created by 16 experts from four countries has been set forth to protect athletes from the potentially fatal health risks that come with drinking too much while exercising.

Mitchell Rosner, MD, a kidney specialist at the University of Virginia School of Medicine who chaired the guideline development group, says that overhydrating with water or sports drinks can lead to a condition called exercise-associated hyponatremia (EAH). When the body has too much water relative to its salt level, the salt level in the blood drops too low which can lead to significant problems.

This condition was once only relevant in the domain of endurance events, but physicians are seeing EAH in a wider array of sports now, leading to the call for new guidelines. Given that many a treehugger is active in the great outdoors, it seems like a relevant issue.

"We have documented at least 14 deaths [from EAH] since 1981, including two deaths last summer in young athletes playing football," Rosner says. "The common feature in all cases is excessive water consumption during athletic events. This is driven by common misbeliefs that overhydration can improve performance and even prevent dehydration. It is worth noting that data demonstrates mild degrees of dehydration do not impair performance."

How to prevent EAH, Rosner says, is to let your body tell you when you need a drink.

"We recommend using your thirst as a guide," he says. "If you drink when thirsty, you will not become hyponatremic and you will not suffer from significant dehydration."

And this applies to whether you’re drinking water or sports drinks; even though sports drink do contain some sodium and may decrease the risk slightly, they are still mostly water.

Here’s what to look out for, says Rosner:

Initial mild symptoms: Cloudy thinking, nausea, headaches.
Severe symptoms: Seizures, severe confusion and coma [you know something's wrong when you slip into a coma].

If you suspect that you or someone nearby may be suffering from EAH, the most important thing is to stop drinking fluids! And then call for medical help.

The new guidelines have been published in the Clinical Journal of Sports Medicine.