What is the appropriate treatment for a patient with suspected gastritis versus food poisoning?

Distinguishing and Managing Gastritis versus Food Poisoning

For a patient presenting with acute gastrointestinal symptoms, the key distinction is timing and symptom pattern: food poisoning typically causes rapid onset (within hours) of vomiting and diarrhea after a specific meal exposure, while gastritis presents with more persistent epigastric pain, nausea, and dyspepsia that may worsen with eating but lacks the acute temporal relationship to a single food exposure.

Clinical Differentiation

Food Poisoning (Acute Gastroenteritis)

• Onset within 1-24 hours after consuming contaminated food (particularly high-risk items like raw fish/sushi, undercooked meat, or improperly stored foods) 1
• Predominant symptoms are vomiting (often severe and early), watery diarrhea, abdominal cramping, and possible fever 1, 2
• Self-limited course, typically resolving within 24-72 hours 3, 4
• Multiple people consuming the same food may be affected 1

Gastritis

• Gradual onset of persistent epigastric discomfort, burning pain, early satiety, and postprandial fullness 5
• Symptoms arise from stomach/duodenal dysfunction rather than acute infection 5
• No clear temporal relationship to a single meal exposure 5
• May have chronic or recurrent pattern rather than acute self-limited course 5

Management of Food Poisoning (Acute Gastroenteritis)

Initial Assessment

• Evaluate for severity markers: persistent vomiting preventing oral intake, signs of dehydration (orthostatic symptoms, decreased urine output), fever >38.5°C, bloody stools, or severe abdominal pain 1, 5
• Assess hydration status through vital signs, mental status, and physical examination 6
• Obtain stool history including frequency, consistency, and presence of blood 5, 6

Mild to Moderate Symptoms (No Severe Dehydration)

Oral rehydration therapy is the first-line treatment and is as effective as intravenous therapy for mild-to-moderate dehydration 3, 4

• Begin oral rehydration solution (8-10 glasses of clear liquids daily such as electrolyte solutions or broth) 5, 1
• Avoid lactose-containing products, alcohol, fatty foods, and raw fish until complete recovery 5, 1
• For persistent vomiting limiting oral intake, administer ondansetron 0.15 mg/kg (or weight-based: 8-15 kg = 2 mg; 15-30 kg = 4 mg; >30 kg = 8 mg) as a single oral dose 2, 7
  • Ondansetron reduces vomiting episodes by 32.9% compared to placebo and decreases need for IV hydration from 54.5% to 21.6% 2
  • Reattempt oral rehydration 30 minutes after ondansetron administration 2
• Gradually reintroduce bland, easily digestible foods (bananas, rice, applesauce, toast, plain pasta) when able to tolerate oral intake 5, 1

Severe Symptoms or Failed Oral Rehydration

If vomiting persists despite ondansetron, or if signs of severe dehydration, fever with dehydration, or bloody stools develop, escalate to intravenous management 6, 1

• Administer intravenous isotonic fluids (normal saline or lactated Ringer's) at 10-20 mL/kg/hr until pulse, perfusion, and mental status normalize 6, 7
• Add dopamine receptor antagonists (metoclopramide 10 mg IV or prochlorperazine 10 mg IV) for refractory nausea 5, 6
• Consider octreotide 100-150 mcg subcutaneously three times daily if severe secretory diarrhea persists (dose escalation up to 500 mcg three times daily may be needed) 5, 6
• Initiate broad-spectrum antibiotics (fluoroquinolone) if fever, bloody stools, or severe systemic symptoms suggest bacterial infection 5, 6
• Obtain stool studies (culture, ova and parasites, Clostridium difficile), complete blood count, and electrolyte panel 6

Management of Gastritis

Initial Approach

Test for Helicobacter pylori infection via stool antigen or urea breath test in all patients with suspected gastritis 5

• If H. pylori positive: Treat with triple therapy (proton pump inhibitor + amoxicillin + clarithromycin) for 10-14 days 8
  • Omeprazole 20 mg twice daily + amoxicillin 1000 mg twice daily + clarithromycin 500 mg twice daily for 10 days 8
  • Continue omeprazole 20 mg once daily for additional 18 days if ulcer present 8

Symptomatic Management (H. pylori Negative or Persistent Symptoms)

• Initiate proton pump inhibitor therapy: omeprazole 20 mg once daily before meals for 4-8 weeks 5, 8
• Avoid foods that trigger symptoms, but do not restrict diet excessively 5
• Regular exercise and stress management may provide benefit 5
• For refractory symptoms, consider neuromodulators (low-dose tricyclic antidepressants) or prokinetic agents 5

Critical Red Flags Requiring Urgent Evaluation

Seek immediate medical attention for any of the following 1:

• Severe abdominal pain suggesting peritonitis or obstruction
• Persistent high fever (>38.5°C) with signs of sepsis
• Bloody vomit or bloody/black tarry stools
• Signs of severe dehydration (altered mental status, inability to maintain oral intake for >24 hours, minimal urine output)
• Age >50 years with new-onset symptoms (concern for malignancy) 5

Common Pitfalls to Avoid

• Do not interpret elevated chromogranin A while patient is taking proton pump inhibitors - this causes false positives and may lead to unnecessary neuroendocrine tumor workup 9
• Do not withhold ondansetron in food poisoning due to outdated concerns about masking serious pathology - evidence shows it safely facilitates oral rehydration and reduces hospitalization 2, 7
• Do not assume normal endoscopy excludes functional dyspepsia/gastritis - the condition involves gut-brain axis dysfunction not visible on structural testing 5
• Do not use loperamide in acute food poisoning with fever or bloody stools - this may worsen bacterial enteritis by reducing pathogen clearance 5