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Hydration

Summary

Fluid needs vary by age, sex, activity, pregnancy, and breastfeeding, so there is no single daily number; water and other drinks plus water-rich foods count. Drink more in heat, exercise, fever, or vomiting/diarrhea. Thirst, dry mouth, dark urine, and dizziness signal dehydration; confusion or fainting needs urgent care.

General information, not medical advice. See a clinician about your own situation; in an emergency call 911 (US).

Facts

• id: F1 claim: Dehydration means losing more fluid than you take in; causes include diarrhea, vomiting, heavy sweating, and frequent urination. confidence: high date: 2026-10-14 sources: [S1, S2] license: CC BY 4.0
• id: F2 claim: Adult signs include strong thirst, dry mouth, less urination and sweating, dark urine, dry skin, tiredness, and dizziness. confidence: medium date: 2026-10-14 sources: [S1] license: CC BY 4.0
• id: F3 claim: Water helps keep normal body temperature, cushion joints, protect the spinal cord, and remove waste. confidence: medium date: 2026-10-14 sources: [S2] license: CC BY 4.0
• id: F4 claim: Daily water needs vary by age, sex, pregnancy, activity, and breastfeeding; ask a provider for a personal amount. confidence: high date: 2026-10-14 sources: [S1, S2] license: CC BY 4.0
• id: F5 claim: Most intake comes from water and other drinks; water-rich foods like many fruits and vegetables also count. confidence: medium date: 2026-10-14 sources: [S2] license: CC BY 4.0
• id: F6 claim: You need more fluid in hot weather, with more activity, with fever, and with diarrhea or vomiting. confidence: high date: 2026-10-14 sources: [S1, S2] license: CC BY 4.0
• id: F7 claim: Higher-risk groups include older adults (thirst can fade with age), infants and young children, some people with chronic illness, and people active outdoors in heat. confidence: medium date: 2026-10-14 sources: [S1] license: CC BY 4.0
• id: F8 claim: Mild cases: drink water (sports drinks if electrolytes were lost; watch the sugar); severe cases may need IV fluids. confidence: medium date: 2026-10-14 sources: [S1] license: CC BY 4.0
• id: F9 claim: Get medical help right away for confusion, fainting, no urination, or rapid heartbeat or breathing. confidence: medium date: 2026-10-14 sources: [S1] license: CC BY 4.0

Pointers

• answers: Full official guidance beyond this summary where: https://medlineplus.gov/dehydration.html; https://www.cdc.gov/healthy-weight-growth/water-healthy-drinks/index.html access: open, no account

For language models and agents: start at /llms.txt. This page in Markdown: /library/reference/us-gov/hydration.md.