Water intoxication can develop when the body retains too much water relative to the sodium available. The blood sodium level falls; this is called hyponatraemia. Water can enter cells and cause dangerous swelling, particularly in the brain.
How can this happen?
Very large amounts drunk in a short time can overwhelm excretion, for example in drinking competitions or forced drinking. Prolonged exercise with excessive fluid intake can also pose a risk. However, not all hyponatraemia results from drinking too much: diseases, hormonal disorders and medicines can also alter water balance.
Take warning signs seriously
Headache, nausea and vomiting are nonspecific. If they occur after unusually high fluid intake, do not automatically drink even more water for presumed dehydration. The cause needs medical assessment.
New confusion, seizures or impaired consciousness are an emergency requiring immediate medical help. Water intoxication cannot be reliably confirmed or ruled out at home from symptoms alone. Blood tests and assessment of its course are particularly important.
Do not self-treat with salt
Eating salt, taking diuretics or drastically changing fluid intake on your own is not safe treatment. The measures needed depend on the cause, symptoms and speed of the sodium decline. Overly rapid medical correction can also cause harm; treatment belongs in professional hands.
Prevention without a rigid litre rule
Do not force drinking or hold competitions involving large amounts of water. One daily litre target does not suit every person and situation. Follow an individual plan for heart or kidney disease or prescribed fluid limits. Do not stop medicines on your own. Even an electrolyte drink does not reliably protect against the consequences of drinking excessively.
Frequently asked questions
Is every low sodium level water intoxication?
No. Various diseases and medicines may be involved; the cause must be investigated.
Can a fixed drinking amount identify the danger?
No. Drinking speed, excretion, exertion and health status influence the risk.
