Oral Rehydration Solution for Hospitalized Adults with Diarrhea
Reduced osmolarity oral rehydration solution (ORS) is the recommended first-line treatment for hospitalized adult patients with mild to moderate dehydration from diarrhea, with intravenous fluids reserved only for severe dehydration, shock, altered mental status, or ORS failure. 1
Initial Assessment of Dehydration Severity
Mild-to-moderate dehydration (6-9% fluid deficit) presents with:
- Decreased skin turgor
- Dry mucous membranes
- Sunken eyes
- Decreased urine output 2
Severe dehydration (≥10% fluid deficit) presents with:
- Altered mental status
- Shock or poor perfusion
- Inability to tolerate oral intake 2
First-Line Rehydration Strategy
For mild-to-moderate dehydration:
- Administer reduced osmolarity ORS (<250 mmol/L) as first-line therapy 1, 2
- Commercial formulations include Pedialyte, CeraLyte, or generic WHO-recommended solutions 1, 2
- Adults should receive ORS ad libitum, up to approximately 2 L/day 2
- Do not use apple juice, Gatorade, soft drinks, or sports drinks for rehydration, as incorrect osmolarity can worsen electrolyte imbalances 2, 3
For severe dehydration:
- Administer isotonic intravenous fluids (lactated Ringer's or normal saline) immediately 1
- Continue IV rehydration until pulse, perfusion, and mental status normalize 1
- Once stabilized, transition to ORS to replace remaining fluid deficit 1, 4
Nasogastric Administration Option
For patients with moderate dehydration who cannot tolerate oral intake:
- Nasogastric administration of ORS may be considered in patients with normal mental status who are too weak or refuse to drink adequately 1, 4
Maintenance and Ongoing Loss Replacement
Once rehydrated:
- Administer maintenance fluids and replace ongoing stool losses with ORS until diarrhea resolves 1, 4
- Resume age-appropriate usual diet during or immediately after rehydration is completed 1, 4
When to Avoid ORS and Use IV Fluids
Absolute indications for IV fluids:
- Severe dehydration with shock 1
- Altered mental status 1
- Failure of ORS therapy 1
- Ileus 1
- Ketonemia (may require initial IV course to enable tolerance of oral rehydration) 1
Adjunctive Therapies: Critical Restrictions
Antimotility agents (loperamide):
- Contraindicated in patients <18 years of age 1, 5
- Contraindicated in suspected or proven inflammatory diarrhea, bloody diarrhea, or fever due to risk of toxic megacolon 1, 5
- May be given to immunocompetent adults with acute watery diarrhea only after adequate hydration 2, 4
- Maximum daily dose is 16 mg (eight 2 mg capsules) 5
- Avoid in patients taking QT-prolonging drugs or with cardiac risk factors 5
Antiemetic agents:
- Ondansetron may be given to facilitate tolerance of oral rehydration in patients >4 years of age with vomiting 1, 4
Common Pitfalls to Avoid
Do not withhold ORS in favor of IV fluids for mild-to-moderate dehydration:
- ORS is equally effective and avoids IV complications 2
- This is the most common error in hospitalized patients 2
Do not give loperamide to:
- Any patient <18 years of age 1, 5
- Patients with bloody diarrhea, fever, or suspected inflammatory diarrhea 1, 5
- Patients with AIDS and abdominal distention (risk of toxic megacolon) 5
Do not use inappropriate fluids:
- Sports drinks, juice, soft drinks, and chicken broth have incorrect osmolarity and electrolyte composition 2, 3
Do not neglect rehydration while focusing on antimicrobial therapy:
- Fluid and electrolyte replacement is the cornerstone of treatment 1, 4
- Antimicrobials are not indicated for most acute watery diarrhea 4
Evidence Quality Note
The recommendation for ORS as first-line therapy is supported by strong, high-quality evidence from the 2017 Infectious Diseases Society of America guidelines 1, which represents the most authoritative and recent guidance on this topic. This recommendation has been consistently reinforced across multiple guideline bodies and has demonstrated a 93% reduction in diarrhea mortality when properly implemented 6.