How to Rehydrate After Diarrhea
Replace both fluids and electrolytes to recover safely from diarrhea-related dehydration.
Quick answer
How to Rehydrate After Diarrhea
- Step 1: Use oral rehydration solution (ORS), not plain water. WHO low-osmolarity ORS (245 mOsm/L) cuts the need for unscheduled IV fluids by about 33% versus the old formula. Take frequent small sips, not large gulps, and replace 100-200 ml of fluid after each loose stool. Avoid sports drinks, soda, and full-strength juice — too much sugar and too little sodium can worsen fluid loss.
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Diarrhea is one of the fastest ways to become severely dehydrated because it causes rapid loss of both water and essential electrolytes (sodium, potassium, and chloride). Rehydrating after diarrhea requires more than just drinking plain water. Oral rehydration solutions (ORS) that contain the right balance of water, salt, and sugar are considered the gold standard for recovery. The World Health Organization estimates that ORS therapy has saved over 50 million lives from dehydration-related deaths.
Effective Rehydration Strategies
Oral Rehydration Solutions
ORS packets (available at pharmacies) contain the ideal ratio of salt, sugar, and water for optimal absorption. They are the most effective way to rehydrate after diarrhea.
Small, Frequent Sips
Drink small amounts frequently rather than large gulps which can trigger more diarrhea. Start with 1-2 tablespoons every 5 minutes and gradually increase.
Electrolyte Replacement
Diarrhea depletes sodium, potassium, and chloride. Sports drinks, coconut water, or broth can help replace these, though ORS is most effective.
BRAT Diet Support
The BRAT diet (bananas, rice, applesauce, toast) provides easy-to-digest food alongside hydration. Bananas also replace potassium lost through diarrhea.
Step-by-Step Rehydration Guide
- Start with small, frequent sips of ORS or clear fluids, about 1 cup every 30 minutes
- Avoid coffee, alcohol, and sugary drinks which can worsen diarrhea and dehydration
- Gradually introduce bland foods as your stomach tolerates them
- Monitor urine color and aim for pale yellow to gauge recovery progress
- Seek medical attention if you cannot keep fluids down or if diarrhea persists beyond 48 hours
Medical Disclaimer: This content is for informational purposes only and does not constitute medical advice. Diarrhea in infants, elderly adults, or immunocompromised individuals can quickly become dangerous. Seek medical attention if dehydration signs are severe or if diarrhea contains blood.
Sources & Citations
- 245 mOsm/L (old: 311) — WHO/UNICEF reduced-osmolarity ORS total osmolarity, down from the old 311 mOsm/L formula[1]
- 75 mmol/L sodium, 75 mmol/L glucose — Sodium and glucose in WHO low-osmolarity ORS[1]
- potassium 20, chloride 65, citrate 10 mmol/L — Potassium and chloride/citrate in WHO low-osmolarity ORS[1]
- ~33% reduction — WHO/UNICEF: new low-osmolarity ORS cut unscheduled IV therapy need[1]
- OR 0.61 (95% CI 0.47-0.81) — Reduced-osmolarity ORS lowers unscheduled IV infusion need vs standard WHO ORS[2]
- stool SMD -0.214; WHO ~20% stool, ~30% vomiting — Reduced-osmolarity ORS reduces stool output and vomiting vs standard WHO ORS[2]
- 2 Na+ : 1 glucose — ORS works via SGLT1 cotransport; glucose is required for sodium absorption and water follows osmotically[3]
- high osmolarity; not recommended — Sports drinks, sodas, and full-strength juices have very high osmolarity (too much sugar, too little sodium) and are not ideal[4]
- failure 16.7% vs 25.0%; index-visit IV 0.9% vs 6.8% — In mild childhood gastroenteritis with minimal dehydration, half-strength apple juice plus preferred fluids had fewer treatment failures than electrolyte solution (not moderate/severe)[5]
- 1 tsp every 1-2 min; 50-200 mL per stool — Give ORS as frequent small sips; WHO 50-100 mL (under 2) / 100-200 mL (2-10) after each loose stool[6]
- no urine 8+ hrs; bloody stool/vomit; confusion/dizziness — Red-flag dehydration signs requiring medical care[7]
- [1]WHO/UNICEF, Oral Rehydration Salts: Production of the new ORS (WHO/FCH/CAH/06.1, 2006) — WHO/UNICEF, Oral Rehydration Salts: Production of the new ORS (WHO/FCH/CAH/06.1, 2006), TABLE 1; Section 2.2, p.3
- [2]Hahn S, Kim Y, Garner P. BMJ 2001;323(7304):81-85 — Hahn S, Kim Y, Garner P. Reduced osmolarity oral rehydration solution for treating dehydration caused by acute diarrhoea in children. BMJ 2001;323(7304):81-85. Cochrane Database Syst Rev CD002847PMID: 11451782
- [3]Buccigrossi V, et al. Sci Rep 2020 — Buccigrossi V, et al. Functional and metabolic effects of oral rehydration solution on intestinal mucosa. Sci Rep 2020PMID: 32385331DOI: 10.1038/s41598-020-64818-3
- [4]Chang JG. Am Fam Physician 2017;96(11):700-701 — Chang JG. Oral Rehydration Therapy. Am Fam Physician 2017;96(11):700-701
- [5]Freedman SB, et al. JAMA 2016;315(18):1966-1974 — Freedman SB, et al. Effect of Dilute Apple Juice and Preferred Fluids vs Electrolyte Maintenance Solution on Treatment Failure Among Children With Mild Gastroenteritis: A Randomized Clinical Trial. JAMA 2016;315(18):1966-1974PMID: 27131100
- [6]Hartman S, et al. Am Fam Physician 2019;99(3):159-165 — Hartman S, et al. Dehydration: Diagnosis and Management. Am Fam Physician 2019;99(3):159-165
- [7]Cleveland Clinic; CDC — Cleveland Clinic; CDC. Red-flag dehydration signs
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
Can I make ORS at home?
Yes, a basic ORS can be made with 1 liter of clean water, 6 teaspoons of sugar, and 1/2 teaspoon of salt. Stir until dissolved. Commercial ORS packets are more precisely formulated.
How long does it take to rehydrate after diarrhea?
Mild dehydration can recover in hours with ORS. Moderate dehydration may take 12-24 hours. Severe dehydration, especially in children or elderly, may require IV fluids.
Should I avoid food while rehydrating?
You do not need to fast. Once you can tolerate fluids, start introducing bland, easy-to-digest foods. Eating helps restore energy and provides additional nutrients for recovery.
Is Gatorade good for diarrhea?
Sports drinks like Gatorade can help but are not ideal. They contain more sugar and less sodium than ORS. For mild cases, they are acceptable but ORS is preferred for significant dehydration.
When should I go to the hospital for diarrhea dehydration?
Seek emergency care if you cannot keep any fluids down, have not urinated in 8+ hours, feel confused or dizzy, have bloody diarrhea, or if an infant has fewer than 3 wet diapers in 24 hours.
Can dairy worsen diarrhea?
Diarrhea can temporarily reduce lactase enzyme production, making dairy harder to digest. Avoid dairy during acute diarrhea and reintroduce gradually as recovery progresses.
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