Just before sport camps and marathon training begins in the US, doctors report a new set of guidelines that should be reviewed to ensure athletes don’t consume more water than they should. Drinking excessive amounts of water can result in potentially serious reductions in blood sodium a condition called hyponatremia. Last year, two high school football players died of exercise-associated hyponatremia (EAH). So, what do you need to do to be on the safe side? Just drink water when you’re thirsty. If you have to drink in advance for various reasons – say, if you’re a marathon runner – keep the excess water at sensible levels.

“Using the innate thirst mechanism to guide fluid consumption is a strategy that should limit drinking in excess and developing hyponatremia (low blood sodium) while providing sufficient fluid to prevent excessive dehydration,” according to recommendations developed at this year’s 3rd International Exercise-Associated Hyponatremia Consensus Development Conference. Tamara Hew-Butler, of Oakland University is lead author of the updated report.

“Our major goal was to re-educate the public on the hazards of drinking beyond thirst during exercise,” Dr. Hew-Butler comments.

Hyponatremia refers to a low level of sodium in the blood. This usually happens because of ingesting too much fluid. At the same time, it could also happen  due to a loss of sodium and body fluid. Sodium is essential for many body functions including the maintenance of fluid balance, regulation of blood pressure, and normal function of the nervous system. Hyponatremia has sometimes been referred to as “water intoxication,” especially when it is due to the consumption of excess water. Symptoms include headache, vomiting, and confusion or seizures.

“The release of these recommendations is particularly timely, just before sports training camps and marathon training begins within the United States—where the majority of EAH deaths have occurred,” Dr. Hew-Butler added.

Staying hydrated is essential to an athlete’s performance, which is why coaches often cheer “drink before you get thirsty”. This can not only be dangerous, but can also worsen performance. This is why the panel suggested that “educational efforts regarding the risks of overhydration should be encouraged and disseminated widely to athletes, coaches, and event management personnel,” as reported in the Clinical Journal or Sport Medicine.

It’s not athletes that need to be careful. During heat waves, it’s common for some people to drink a lot more water than they need to. In other instances, people just don’t give drinking too much water a second thought. They think the worst that can happen is you get bloated. In 2007, a 28-year-old California woman died after competing in a radio station’s on-air water-drinking contest. After downing some six liters of water in three hours in the “Hold Your Wee for a Wii” (Nintendo game console) contest, Jennifer Strange vomited, went home with a splitting headache, and died from  water intoxication. In 2005 a fraternity hazing at California State University, Chico, left a 21-year-old man dead after he was forced to drink excessive amounts of water between rounds of push-ups in a cold basement. Also, people who have taken MDMA (“ecstasy”) have died after consuming copious amounts of water trying to rehydrate following long nights of dancing and sweating.

“Every single EAH death is tragic and preventable, if we just listen to our bodies and let go of the pervasive advice that if a little is good, than more must be better.”