Moderate Acute Alimentary Infections & Inflammations

Acute Gastroenteritis (Stomach Flu)

Acute infection of the stomach and intestines causing diarrhea and vomiting.

Primary risk age: All ages; dehydration risk is highest in infants and toddlers.

Urgency: Moderate
Typical age: All ages; dehydration risk is highest in infants and toddlers.
Body system: Gastrointestinal System

Typical course: Vomiting usually settles within 1–2 days; diarrhea typically lasts 3–7 days.

Reviewed against AAP · CDC · WHO · NHS guidance Last reviewed 2026-06-13

1. Summary & Pathophysiology

Acute infection of the stomach and intestines causing diarrhea and vomiting.

Pathophysiology (Development Path)

Infection of the gut lining disrupts fluid absorption and increases secretion, producing watery diarrhea and vomiting that can quickly deplete body fluids in small children.

Primary Causes & Etiology

Most often viruses (rotavirus, norovirus); also bacteria and parasites from contaminated food or water and person-to-person spread.

2. Symptom Continuum

Early Onset Signs
Nausea, vomiting, and the onset of loose or watery stools, sometimes with low-grade fever.
Progressive Phase
Frequent watery diarrhea, crampy abdominal pain, reduced appetite, and early signs of dehydration such as decreased urination.
Severe Indicators
Signs of significant dehydration (no wet diaper for 8+ hours, no tears, sunken eyes, lethargy), blood in stool, persistent green vomiting, or high fever.

3. Clinical Verification

Clinical diagnosis; stool testing is reserved for blood in stool, prolonged illness, recent travel, or suspected bacterial or parasitic causes.

4. Care & Elements Plan

Primary Care Treatment Plan

The priority is rehydration with oral rehydration solution. Most children do not need medication; antibiotics are only for specific confirmed bacterial infections.

Home Support Elements

Give frequent small amounts of oral rehydration solution, continue breastfeeding, and resume a normal diet as tolerated once vomiting settles. Avoid sugary drinks, which can worsen diarrhea.

Generic Active Ingredients (No Brands)

Oral rehydration solution (ORS) (electrolyte and glucose active formulation, the mainstay of treatment)
zinc (active supplement that shortens diarrhea in young children)
rotavirus vaccine (preventive).

Lists active elements only. Never administer self-designed therapies.

5. Doctor Critical Lines

Critical Thresholds: When to See a Doctor

Seek care for signs of dehydration, blood in stool, persistent vomiting preventing fluids, high fever, severe abdominal pain, or illness in a young infant.

6. Vaccine & Prevention

Routine Prophylaxis (Prevention)

Handwashing, safe food and water, and rotavirus vaccination prevent many cases.

Immunization Context

The oral rotavirus vaccine series in infancy prevents the most severe viral gastroenteritis.

7. Timelines & Outlook

Active Timeline

Vomiting usually settles within 1–2 days; diarrhea typically lasts 3–7 days.

Expected Prognosis

Excellent with adequate rehydration; most viral cases resolve without complications.

Potential Untreated Complications

Dehydration and electrolyte imbalance, and in some bacterial infections, hemolytic uremic syndrome.

Moderate

Rotavirus Gastroenteritis

Acute Viral Enterotoxin-Mediated Intestinal Infection

Infants and toddlers aged 3 to 24 months (Highly contagious)

Emergency

Pediatric Appendicitis

Acute Obstruction & Inflammation of the Vermiform Appendix

School-aged children and adolescents (Peak incidence: 10 to 19 years; rare under 2 years)