An athlete dies after drinking a lot of water after a workout. A fraternity hazing incident results in the death of a pledge forced to drink large amounts of water in between rounds of push ups. A woman participates in a contest to win a Wii video game by drinking 3 liters of water without urinating for several hours, and is later found dead in her home. Autopsies reveal that all these persons died of water intoxication or water poisoning.
We hear constantly that most people do not drink enough water throughout the day, that we are virtually made of water, and that water is the most crucial nutrient for life. But occasionally we hear of someone dying from drinking too much water. How can there be too much of such a good thing?
First, it is pretty difficult to drink too much water. Normally, when you start to take in too much water, your body gets rid of it by increasing the need to urinate. However, when you are engaging in strenuous exercise, you are losing a large amount of water through sweating, and your body responds by secreting antidiuretic hormone (ADH) which suppresses the urge to urinate. This is why the majority of deaths from over consumption of water happen to athletes.
Second, it is not so much the large amount of water that kills you, it is the resulting imbalance of sodium and electrolytes in your system. Normally your kidneys and individual cells are capable of fine tuning the balance of sodium, electrolytes and water in your system by drawing more or less water into the cells. However, when your body is swamped by an overdose of water with too little sodium and electrolytes, a condition called hyponatremia (literally too little salt in the blood) results.
Cells respond by trying to take in more water, which causes them to swell. Cells are capable of swelling quite a bit without danger, normally, provided there is room for them to get larger. The problem comes when hyponatremia causes brain cells to swell with water, as the skull does not allow this room for expansion, and any fluids in the brain are already sharing space with cerebrospinal fluid that is meant to be there. Just as when the brain swells due to injury, headache, convulsions, coma, and death can quickly follow.
The best preventative to this condition for athletes is to be careful to balance water intake with consumption of sports drinks that contain sodium and electrolytes. If your normal thirst awareness is not impeded by drugs or a medical condition, trust it to tell you when you have had enough to rehydrate.
Early symptoms of water intoxication can resemble those of alcohol intoxication. If you are working out with others or coaching kids or athletes at a training session, watch out for these signs:
Loss of coordination
Complaints of headache
Seizures or convulsions
Loss of consciousness
If you see any of these symptoms developing, try to determine how much water and/or sports drinks the individual has recently had, and call for an ambulance. Hyponatremia can quickly become alife-or-death emergency and needs prompt medical treatment.