Overhydration Vs. Dehydration

Advice about preventing dehydration is especially prevalent during the hot summer months when the amount of fluid lost through sweat can reach dangerous levels. There is another danger related to hydration that is lesser known, hyponatremia, a potentially fatal condition that can result from drinking too much water.

When too much water is consumed, sodium levels can reach dangerously low levels, leading to a condition known as hyponatremia. Endurance athletes are at a particularly high risk for hyponatremia, also called "water intoxication" or  exercise associated hyponatremia. In a 2002 study of 488 Boston Marathon runners, 13 percent had hyponatremia at the end of the race.