Ill-effects of drinking too much water

Hydration is a cornerstone of good health. But experts warn that drinking water in excess, especially over a short time, can lead to serious, even life-threatening problems.

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Overhydration, also called water intoxication or dilutional hyponatremia, occurs when the body holds more water than the kidneys can safely excrete. When sodium and other electrolytes are diluted, cells swell. If this swelling occurs in brain tissue, dangerous pressure can build inside the skull.

Symptoms often begin subtly. Clear or very pale urine and frequent urination are early signs that the body has more water than it needs. Along with these may come tiredness, nausea or vomiting, headaches, and swelling in extremities such as hands or feet. These signals may feel mild—a faint headache, a sense of bloating, fatigue—but ignoring them can allow the condition to worsen.