Exercise-Associated Hyponatremia: Why More Water Is Not Always Safer
Exercise-associated hyponatremia is low blood sodium arising during or shortly after exercise. The central preventable driver is often drinking more fluid than the body can excrete, which dilutes blood sodium. Sodium loss may contribute, but taking salt does not make unlimited drinking safe.
This is a medical emergency topic. Confusion, severe headache, repeated vomiting, seizures, altered behaviour or collapse during an endurance event require urgent medical assessment.
Updated 25 August 2026. This is general sports nutrition information, not individual medical advice.
dehydration and hyponatremia are different
Both can involve nausea, headache and poor performance, so guessing at an aid station is risky. A dehydrated athlete has lost body water; a hyponatraemic athlete may have gained or retained excess water relative to sodium.
Automatically telling every struggling athlete to drink more can worsen the second problem. Event medical teams need the context and, where indicated, blood sodium measurement.
drink to a plan with feedback
Consensus guidance emphasises avoiding overdrinking. Thirst, conditions, sweat observations, aid-station access and body-mass trends can inform a plan, but no single number fits every athlete.
Do not aim to gain weight during a race through fluid intake. Do not use a high sodium product as permission to force litres beyond thirst.
where sodium products fit
Sodium can support palatability, fluid retention and replacement of sweat losses in the right context. It is one part of a plan, not an antidote to excess water.
Our sweat-rate hydration guide explains how to gather personal data without turning it into a rigid drinking rule.
the bottom line
Exercise-associated hyponatremia is low blood sodium arising during or shortly after exercise. The central preventable driver is often drinking more fluid than the body can excrete, which dilutes blood sodium. Sodium loss may contribute, but taking salt does not make unlimited drinking safe. Turn the principle into a plan, test it under relevant training pressure and keep clear notes on what actually works.
For a food-first option providing 30g carbohydrate and 250mg sodium per pouch, see 2THRV Whole Food Fuel Gel. Product does not replace a complete daily diet or individual medical care.
frequently asked questions
can you get hyponatremia while taking electrolytes?
Yes. Excess fluid intake can still dilute blood sodium even when some sodium is consumed.
is clear urine always the goal before a race?
No. Persistently forcing fluid to produce clear urine can indicate overdrinking.
what should i do if a runner is confused?
Stop the event and seek urgent medical help. Do not assume the answer is more water.
research and guidance
whole-food endurance fuel