During periods of extreme heat, we are often told: “Drink some water”. But it is also possible to drink it too much, to the point of endangering his health. This risk is called hyponatremia.
What is hyponatremia?
Hyponatremia is an abnormal drop in blood sodium (< 135 mmol/L). It occurs when we bring too much water compared to salt available, or we loses too much salt (sweating, certain medications) without compensating.
The blood then becomes “diluted”, water enters the cells which swell (including in the brain), which can lead to serious complications.
Symptoms to watch out for
- Nausea, vomiting
- Headaches
- Confusion, disorientation, unusual fatigue
- Edema, muscle cramps
- Emergency (severe forms): convulsions, coma
Who is most at risk?
- Elderly : decreased perspiration, less effective water elimination.
- Chronic diseases : kidney or heart failure, diabetes, cancer.
- Medicines : diuretics, psychotropic drugs (e.g.: antidepressants).
- Athletes/workers in heat : heavy sweating not compensated for by salt.
Why does the heatwave increase the risk?
Sweating removes a lot of water (≈99%) and also minerals (including sodium). Drinking only water (tap or bottle) is not always enough to restore balance: you also need a sodium intake via suitable food or drinks.
How much to drink safely?
- General population : avoid exceeding 3 to 4 L of liquids/day.
- People at risk : approximately 1.5 L/day (excluding water from food), according to medical advice.
Avoid “chugs” : ingesting very large quantities of water in a very short time can be dangerous.
How to hydrate properly during the heatwave?
- Drink regularly in small sips, without forcing yourself excessively.
- Alternate pure water and mineral intake : broths, more sodium mineral waters, salty foods (tomato, olives, cheese in reasonable quantities).
- For exercise and work in heat: consider oral rehydration drinks or mineral water richer in sodium.
- Do not drink several liters at once: split your catches.
- If you are fragile (age, illness, medication): ask for a medical advice to adjust your intake.
What to do if you have symptoms?
- Light shapes : temporarily reduce fluid intake and consult if signs persist.
- Severe signs (confusion, convulsions): call emergency services immediately.
Key message : during the heatwave, hydrate yourself regularly, but keep the balance: water and minerals.
