Does Water Help Hangovers?
Dehydration is a major contributor to hangover symptoms, and water helps significantly.
Quick answer
Does Water Help Hangovers?
Water helps hangovers only partially. Alcohol suppresses vasopressin (ADH) in a biphasic way (Harper 2018) and raises urine output, so replacing fluid eases headaches, dry mouth, and dizziness. But hangovers are also driven by inflammation and acetaldehyde, which water cannot fix. Eggleton (1942) estimated roughly 10 mL of extra urine per gram of alcohol, so pace drinks, alternate with water, and add electrolytes the morning after.
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While hangovers have multiple causes beyond dehydration (including inflammation, acetaldehyde toxicity, and electrolyte disruption), dehydration is one of the primary contributors to hangover symptoms. Alcohol is a potent diuretic that inhibits vasopressin, the hormone that tells your kidneys to retain water. This means you can lose significantly more fluid than you consume while drinking. Headaches, fatigue, dry mouth, and dizziness associated with hangovers are largely dehydration symptoms that water can help address.
How Alcohol Dehydrates You
Vasopressin Suppression
Alcohol suppresses vasopressin (ADH), the hormone that controls water reabsorption. Without it, your kidneys produce much more urine, causing rapid fluid loss.
Net Fluid Loss
For every standard alcoholic drink, you may lose an additional 100-200 mL of water beyond what you consumed. Over several drinks, this creates a significant fluid deficit.
Electrolyte Depletion
Increased urination from alcohol flushes out sodium, potassium, and magnesium. These electrolyte losses contribute to headaches, muscle aches, and fatigue.
Delayed Effects
Dehydration worsens overnight as you sleep without drinking water. By morning, the cumulative fluid deficit manifests as classic hangover symptoms.
Hydration Strategies for Drinking Occasions
- Drink a glass of water between each alcoholic beverage to slow fluid loss
- Hydrate well before you start drinking to build a fluid buffer
- Drink at least 2 large glasses of water before going to bed after drinking
- Choose electrolyte-containing drinks the morning after to replace lost minerals
- Eat before and while drinking, as food slows alcohol absorption and provides some hydration
Medical Disclaimer: This content is for informational purposes only and does not constitute medical advice. Excessive alcohol consumption is harmful to health. If you choose to drink, do so in moderation. If you have concerns about alcohol use, speak with a healthcare provider.
Sources & Citations
- ~10 mL urine per 1 g alcohol (n=1, approximate) — Alcohol's diuretic effect is dose-dependent on alcohol amount; Eggleton's classic single-subject estimate is roughly 10 mL extra urine per gram of alcohol.[1]
- Wine 536 vs 504 mL (p<0.03); Spirits 471 vs 450 mL (p<0.001); Beer 829 vs 836 mL (NS), 4 h — At a fixed 30 g alcohol dose, wine (13.5% ABV) and spirits (35% ABV) significantly raised 4-hour urine output while 5% beer did not differ from non-alcoholic beer; all differences resolved by 24 hours.[2]
- Euhydrated 1279 vs 1121 mL (p<0.001); Hypohydrated 261 vs 174 mL (p=0.057, NS) — Alcohol's diuresis is significant when starting euhydrated but is blunted when already dehydrated, so prior hydration status changes how much fluid alcohol costs you.[3]
- Higher total urine all alcohol vs water (p=0.01); late copeptin rebound (p=0.02) at BAC 0.8 per mille — Using copeptin as a vasopressin surrogate, alcohol prolonged suppression and raised total urine output versus water, with a later compensatory rebound.[4]
- AVP falls on rising BAC, rebounds on cessation (biphasic) — Plasma vasopressin (ADH) suppression from alcohol is biphasic, not a sustained shutdown: it falls as blood alcohol rises and rebounds on cessation.[5]
- ~250 mg potassium / 105 mg sodium per 100 g (~600 mg K per 240 g cup) — Coconut water is high in potassium but low in sodium, supporting its use for replacing potassium lost during alcohol-driven diuresis.[6]
- [1]Eggleton 1942 — Eggleton MG. Diuretic action of alcohol in man. J Physiol. 1942;101(2):172-191.DOI: 10.1113/jphysiol.1942.sp003973
- [2]Polhuis 2017 — Polhuis KCMM, et al. The Diuretic Action of Weak and Strong Alcoholic Beverages in Elderly Men. Nutrients. 2017;9(7):660.PMID: 28672801DOI: 10.3390/nu9070660
- [3]Hobson & Maughan 2010 — Hobson RM, Maughan RJ. Hydration status and the diuretic action of a small dose of alcohol. Alcohol Alcohol. 2010;45(4):366-373.PMID: 20497950DOI: 10.1093/alcalc/agq029
- [4]Sailer 2020 — Sailer CO, et al. Influence of alcohol consumption on copeptin levels and sodium-water homeostasis. Am J Physiol Renal Physiol. 2020;318(3):F702-F709.PMID: 31961713DOI: 10.1152/ajprenal.00458.2019
- [5]Harper 2018 — Harper KM, et al. Vasopressin and alcohol: a multifaceted relationship. Psychopharmacology (Berl). 2018;235(12):3363-3379.PMID: 30392132DOI: 10.1007/s00213-018-5099-x
- [6]USDA FDC 170174 — USDA FoodData Central. Coconut water (liquid from coconuts), FDC 170174. Agricultural Research Service.
Last reviewed: 2026-06-21. Every figure on this page is sourced to the named primary references above.
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Frequently Asked Questions
Should I drink water before bed to prevent a hangover?
Yes, drinking 2-3 glasses of water before bed can significantly reduce hangover severity. This helps counteract the fluid deficit created by alcohol's diuretic effect.
Is coconut water good for hangovers?
Coconut water provides both hydration and electrolytes (especially potassium), making it a good choice for hangover recovery. However, regular water with a balanced meal is also effective.
Can water completely prevent a hangover?
Water can reduce but not completely prevent hangovers. Alcohol causes inflammation and acetaldehyde toxicity that water cannot address. However, staying hydrated significantly reduces symptom severity.
How much water should I drink for a hangover?
Drink at least 4-6 cups of water the morning after to begin rehydrating. Continue drinking water throughout the day. Adding electrolytes can speed recovery.
Is the hair of the dog myth true?
Drinking more alcohol to cure a hangover only delays and worsens symptoms. It adds more dehydration on top of the existing deficit. Water and rest are far better remedies.
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