What is Hyponatremia?

Hyponatremia (often called water intoxication) occurs when the sodium concentration in your blood is abnormally low. In runners, this is usually caused by drinking too much plain water during a long race, diluting the sodium levels.

Why is it Dangerous?

It causes cells to swell. In the brain, this swelling can lead to:

• Nausea and vomiting
• Confusion and disorientation
• Seizures
• Coma and even death

Prevention

"Drink to thirst." Do not force yourself to drink at every aid station if you aren't thirsty. Also, consume electrolytes (sodium) alongside water during long endurance events.