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You can drink too much water—seriously

Believe it or not, too much water can kill you.

People working, training or competing in hot weather can be at greater risk.

“Folks know in hot, humid conditions they must drink enough to avoid dehydration, because it’s very easy to become dehydrated and risk heat cramps, heat exhaustion or even heat stroke”, said Amy MacDougall, MD, with Carle Sports Medicine.

“But if you drink too much fluid, your life could be in danger.”

Drinking too much, and losing a lot of salt through sweating, can lead to a rare but risky condition called hyponatremia. Hyponatremia is a low concentration of sodium in the blood. Cells in the body swell because too much water dilutes the sodium.

“Initially, you may feel your fingers and feet puff up,” Dr. MacDougall said. “But if electrolytes get too low, it can make you feel light-headed or nauseated.”

“In very bad cases, hyponatremia can cause the brain to swell, leading to seizures, coma and possibly death,” she added.

While rare, hyponatremia is a growing concern.

“We tend to see this in people participating in ultra-marathons and other long endurance events,” she said.

“But we are starting to see hyponatremia in people who train for marathons and half-marathons, football players and even people doing hot yoga. These are situations where people ended up over-drinking to avoid dehydration but end up putting themselves at risk going too far.”

Hyponatremia can strike non-athletes, too. In fact, the park rangers at the Grand Canyon see it in vacationers, so they regularly counsel hikers about proper hydration.

“More people in the Grand Canyon are hospitalized in the ICU due to hyponatremia than dehydration,” Ben Cooper, Preventative Search and Rescue supervisor at Grand National Park, said in Grand Canyon News.

“We can fix dehydration, but low sodium is very difficult to fix.”

So, how much fluid should people drink?

  • Most adults should drink about 500 milliliters per every hour of hard exercise.
  • Athletes should sip fluid every 15 to 20 minutes.
  • People working should drink when thirsty, following similar guidelines.

Drinking sports drinks may reduce the chance of hyponatremia, but it doesn’t remove all risk.

“Listen to your body. Thirst is a precisely tuned alert. Drink to quench your thirst and your body should be fine,” Dr. MacDougal said.

If you think you have hyponatremia or if you are suffering from dehydration, get to the emergency room immediately.

If you have any sports medicine questions, including how much water to drink, please visit the free Carle Sports Medicine walk-in clinic weekday mornings and afternoons.