Dehydration can contribute to headache, but the evidence is limited. See what studies show, what they do not prove, and when headache needs medical care.
Evidence-based guides
Hydration guidance you can actually use.
Practical guides on daily intake, dehydration, exercise, sleep and habits. Sources are linked in every article, with important limits stated clearly.

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How much water do you really need each day? Compare EFSA, NHS and US guidance, see what counts toward intake, and choose a practical hydration target.
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Extra water may slightly increase skin hydration in some people, but the evidence is limited. See what studies show about dry skin and moisturizers.
Habit formation does not follow a 21-day rule. Research shows wide variation, with many health habits taking months rather than weeks to become automatic.
Exercise hydration depends on sweat loss, duration, heat and intensity. Learn what major sports-medicine guidance supports before, during and after exercise.
Drinking water before bed is not automatically good or bad. Learn how evening fluids relate to nocturia, sleep disruption and daily hydration.

Do you really need electrolyte drinks? Learn when water is enough, when electrolytes can help, and how sports drinks differ from oral rehydration solution.

How much water do you really need each day? Compare EFSA, NHS and US guidance, see what counts toward intake, and choose a practical hydration target.

Learn the common signs of dehydration, what urine colour and thirst can tell you, which symptoms are nonspecific, and when to seek medical help.

There is no perfect drinking interval. Learn how to spread fluids through the day, use thirst well, and place reminders where they actually help.

Learn how to replace fluids during fever, vomiting and diarrhoea, when oral rehydration solution helps, and which warning signs need medical care.

Water is not the only source of hydration. Learn how coffee, tea, milk, sparkling water and food contribute to your daily fluid intake.

Hot weather raises your fluid needs, but there is no single summer target. Learn how to adjust your intake, use electrolytes and spot warning signs.

Forget rigid water rules. Use eight practical habits to make drinking water easier to remember throughout a normal day.