Heatwave dehydration guidance for public health

Health experts emphasize that staying properly hydrated during extreme heat and high humidity requires more than just drinking water. Recommended daily fluid intake varies—about 2 L for women and 2.5 L for men—but increases with temperature, physical activity and individual factors. During heatwaves, the body loses water, sodium, potassium and other electrolytes through sweat, making mineral balance crucial.

Signs of dehydration can be subtle: persistent fatigue, dark urine, reduced urination frequency, headaches, or difficulty concentrating. Vulnerable groups—including the elderly, people with heart or respiratory conditions, and those with chronic illnesses—are at higher risk of severe complications such as respiratory distress or heat‑related illness.

Nutrition advice highlights electrolyte‑rich foods and mineral‑rich waters. Fruits and vegetables such as watermelon, cucumber, citrus, and lettuce supply up to 30 % of fluid needs. Mineral waters high in calcium, magnesium or bicarbonates can support bone health, muscle function and digestion, especially for women, athletes and those on specific diets. A balanced breakfast with water‑rich foods, protein and complex carbs is recommended to sustain hydration throughout the day.

Preventive measures include monitoring weather forecasts, avoiding direct sun between 11 am‑4 pm, using air‑conditioning or fans, drinking fluids regularly—not only when thirsty—and seeking medical help if breathlessness persists, lips turn blue, or oxygen saturation falls below 93 %. These guidelines aim to reduce heat‑induced dehydration and its health impacts across regions experiencing severe summer temperatures.