Which types of drinks actually help keep you hydrated in extreme heat?

Paris – 06/07/2026: During prolonged heatwaves, drinking water regularly is the most important preventive measure against dehydration—ideally before feeling thirsty. French health authorities such as Santé publique France emphasize that fluids and salts lost through sweating must be continuously replenished. Insufficient intake can lead to fatigue, dizziness, headaches and, in severe cases, heatstroke with circulatory collapse.

Water is the standard choice. Tap water is considered safe in France and sufficient for everyday needs. Those who find its taste bland can choose unsweetened herbal tea, diluted fruit juice or water with lemon slices. Regularity is important: small amounts consumed at short intervals are easier to tolerate than drinking infrequently in large quantities. Very cold drinks offer no proven benefit over cool or lukewarm beverages and may cause stomach discomfort in sensitive people.

When sweating heavily—for example during physical work, exercise or in places with little air conditioning—sodium replacement is especially important. Salty drinks, clear broth or suitable oral rehydration solutions are recommended. For people exercising for long periods or at high intensity, electrolyte drinks with a moderate sugar content may be used; they should have a balanced ratio of water, sodium and carbohydrates. For infants, older adults and people with chronic illnesses: a drinking plan with small, frequent portions is recommended, possibly combined with electrolyte solutions as directed by a doctor.

Unsuitable options include sugary soft drinks, highly concentrated pure fruit juices, alcohol and heavily caffeinated beverages. They may increase water excretion, reduce the sensation of thirst or adversely affect blood sugar levels. Iced coffee, energy drinks and mate or concentrated black tea should only be consumed in small amounts in hot weather. So-called “detox” or “miracle” waters also cannot replace a balanced supply of water and salt.

Warning signs of dehydration include dry mouth, dark or reduced urine, dizziness, muscle cramps, unusual fatigue and confusion. If these symptoms occur, drink immediately, preferably water or a suitable oral rehydration solution. If symptoms persist or are accompanied by vomiting, impaired consciousness or very little urine output, seek medical help immediately.

In addition to choosing drinks, basic advice remains important: reduce strenuous activity, wear light clothing, cool or shade rooms, ventilate regularly and use fans or air conditioning appropriately. Families, neighbors and caregivers should pay particular attention to infants, very elderly people and those living alone. Updated information and heat warnings are regularly published by Santé publique France, Ameli health insurance and the Ministry of Health on their information pages.