The Shocking Science of Water Intoxication

The phrase “water intoxication” sounds like a paradox, but the science behind it is shockingly real. A medical expert in nephrology explains the cellular-level chaos that ensues when the body is flooded with too much water, turning the very substance of life into a potential poison.
Your kidneys are your body’s primary line of defense against fluid overload, but they can only process so much at once. For most people, a total daily fluid intake of two to three liters is a safe and effective amount for maintaining health.
When you drink water far faster than your kidneys can excrete it, the excess fluid enters your bloodstream. This dilutes the concentration of sodium, a key electrolyte. This creates an osmotic imbalance, causing water to move from the blood into your body’s cells in an attempt to restore equilibrium.
This cellular swelling is the core danger of water intoxication. While it affects the whole body, it is most perilous in the brain. The rigid skull provides no room for brain cells to expand, leading to increased intracranial pressure. This can cause severe neurological symptoms, including seizures, coma, and even death.
This shocking chain of events is why moderation is so crucial. While rare, water intoxication is a real risk for those who over-consume, such as participants in water-drinking contests or athletes who rehydrate incorrectly. For safe hydration, simply drink to your thirst.