What is the cause of my persistent gastrointestinal symptoms, including dry heaving, nausea, acid reflux, and epigastric pain, following a recent episode of diarrhea treated with anti-diarrheal medication?

Post-Infectious Gastroenteritis with Possible Functional Dyspepsia or GERD

Your symptoms most likely represent post-infectious gastroenteritis that has evolved into either functional dyspepsia or gastroesophageal reflux disease (GERD), and you should start high-dose proton pump inhibitor therapy (omeprazole 40 mg once daily before breakfast) while monitoring for alarm symptoms that would require urgent evaluation. 1, 2

Immediate Concerns to Rule Out

Before attributing your symptoms to a benign cause, several life-threatening conditions must be excluded:

• Obtain an ECG immediately to rule out myocardial infarction, which can present with isolated epigastric pain, especially in women, diabetics, and elderly patients, with mortality rates of 10-20% if missed 1, 2, 3
• Check vital signs for tachycardia ≥110 bpm, fever ≥38°C, or hypotension, which may indicate perforation, sepsis, or complications 2, 3
• Assess for peritoneal signs (abdominal rigidity, severe tenderness) which would suggest perforated peptic ulcer with 30% mortality if treatment is delayed 1, 2

Most Likely Diagnosis

Your symptom pattern suggests:

• Functional dyspepsia or GERD is most probable given the combination of epigastric pain, nausea, and acid reflux following a recent diarrheal illness 4
• Approximately 66% of patients with GERD and heartburn also experience epigastric pain, and patients frequently cannot distinguish which symptom is predominant 4, 2
• The recent diarrhea treated with anti-diarrheal medication may have been acute infectious gastroenteritis, which can trigger functional gastrointestinal symptoms that persist after the infection resolves 5, 6

Critical pitfall: Anti-diarrheal medications can mask ongoing infectious processes or complications. The fact that diarrhea stopped with medication doesn't exclude post-infectious inflammation or secondary complications. 4

Recommended Diagnostic Workup

Based on your symptoms, you need:

• Complete blood count to assess for anemia from occult bleeding, which is the most common peptic ulcer disease complication 1, 2
• Stool testing for occult blood 1
• H. pylori testing using stool antigen test or urea breath test, as this is a major risk factor for peptic ulcer disease 1
• Serum electrolytes and glucose 2, 3

Do NOT need immediate endoscopy unless alarm symptoms develop (see below). 1

Treatment Algorithm

First-Line Therapy (Start Immediately)

• Omeprazole 40 mg once daily, taken 30-60 minutes before breakfast for optimal acid suppression, with expected healing rates of 80-90% for duodenal ulcers and 70-80% for gastric ulcers 1, 2, 3
• Avoid all NSAIDs completely as they worsen peptic ulcer disease and increase bleeding risk 1, 2, 3

Symptomatic Relief for Nausea

• Ondansetron 8 mg sublingual every 4-6 hours (obtain baseline ECG first due to QTc prolongation risk) 2, 3
• Alternatives: promethazine 12.5-25 mg orally/rectally every 4-6 hours, or prochlorperazine 5-10 mg every 6-8 hours 2

Critical Lifestyle Modifications

• Eliminate carbonated beverages and spicy foods during the acute phase 1
• Avoid late meals and remain upright for 2-3 hours after eating to reduce nocturnal acid exposure 1, 2, 3
• Immediate smoking cessation and alcohol reduction/cessation as these have a synergistic dose-dependent effect on gastric ulcer risk 2, 3

H. Pylori Management

• If H. pylori testing is positive: Start triple therapy (PPI + two antibiotics) 1
• If H. pylori testing is negative: Continue omeprazole alone 1

When to Seek Urgent Care

Go to the emergency department immediately if you develop:

• Sudden, severe epigastric pain with fever and abdominal rigidity (suggests perforation with 30% mortality) 1, 2
• Vomiting blood (hematemesis) or black tarry stools 1, 2
• Persistent vomiting that prevents oral intake 4
• Severe dehydration, bloody stools, or persistent fever 5, 6

Follow-Up and Endoscopy Indications

• Reassess symptoms after 4-8 weeks of PPI therapy 1
• Refer for urgent endoscopy if:
  • Symptoms persist despite 4-8 weeks of PPI therapy 1
  • Alarm symptoms develop: unintentional weight loss, difficulty swallowing (dysphagia), vomiting blood, or progressive worsening of symptoms 1, 2
  • Anemia is detected on blood work 2, 3

Important Caveats

• Do not assume benign disease based on antacid response alone - peptic ulcer disease often fails to respond to antacids but responds to PPIs 1
• Persistent vomiting (dry heaving) suggests another disorder beyond simple functional dyspepsia and warrants closer evaluation 4
• The overlap between functional dyspepsia, GERD, and irritable bowel syndrome is substantial - approximately 80% of people with dyspepsia in community surveys have functional dyspepsia with no organic cause found on endoscopy 4
• Your recent diarrhea may have been part of an infectious gastroenteritis that has now evolved into post-infectious functional symptoms, which can persist for weeks to months 5, 7, 6