Is it possible to drink too much water? - Hyponatremia

I guess it depends where you are, but in North America we're told constantly to make sure we drink lots of water to stay hydrated. But as with everything else, it is possible to have too much of it.

Hyponatremia (or water poisoning) happens when you have had so much water to drink that it has disrupted the normal balance of electrolytes (salts) in your bloodstream. Severe cases (when electrolyte levels drop too low in less than 48 hours) can result in brain swelling, which can lead to all sorts of fun medical issues including comas. If it happens over a longer period of time, the symptoms will be significantly less noticeable (and may be completely ignored). These include dizziness, loss of appetite and muscle cramps.

Most people do not have to worry about getting water poisoning. Almost all deaths caused by drinking too much water were the result of exercising for extended periods (while drinking water and not replenishing electrolytes in any way) or drinking contests. The more common causes of hyponatremia are related to other medical issues that have symptoms such as vomiting or diarrhea (i.e. losing fluids rich in salts instead of consuming too much of fluids with no salts).

If you are worried about getting water poisoning because of the amount of fluids you tend to consume, try drinking sports drinks instead of water. I used to work as a lifeguard on a beach all summer and gave myself mild cases of hyponatremia all the time and fixed it by buying a big tin of Gatorade powder.