What is the most appropriate initial management for a 68‑year‑old man presenting with four days of epigastric discomfort, bloating, heartburn, and diarrhea?

Initial Management of Acute Gastroenteritis with Dyspeptic Symptoms

Begin immediate oral rehydration while simultaneously excluding life-threatening cardiac and surgical emergencies, then initiate empirical proton pump inhibitor therapy pending Helicobacter pylori testing.

Immediate Life-Threatening Exclusions (First 10 Minutes)

• Obtain an ECG within 10 minutes to exclude myocardial infarction, which can present atypically with isolated epigastric pain, particularly in elderly men, diabetics, and those with cardiovascular risk factors (mortality 10-20% if missed) 1, 2.
• Check vital signs immediately for tachycardia ≥110 bpm, fever ≥38°C, or hypotension, which predict perforation or sepsis with high specificity 1, 2.
• Measure cardiac troponins at 0 and 6 hours if any concern for acute coronary syndrome 2.

Essential Laboratory Workup

• Order complete blood count to identify anemia (an alarm feature mandating urgent endoscopy) 1, 2.
• Obtain comprehensive metabolic panel including electrolytes, glucose, and renal function to assess dehydration 2.
• Check serum amylase (≥4× normal) or lipase (≥2× normal) to exclude acute pancreatitis (sensitivity/specificity 80-90%) 1, 2.
• Send stool testing for Clostridium difficile in all new presentations of diarrhea, regardless of antibiotic history 3.

Primary Treatment: Rehydration

Rehydration is the priority treatment and must be initiated immediately before any other intervention 2, 4. The majority of acute infectious diarrhea cases are self-limited and resolve without specific intervention beyond volume correction 4.

• Encourage 8-10 large glasses of clear liquids per day 2.
• Resume an age-appropriate diet immediately after or during rehydration 2.
• Recommend small, frequent meals: bananas, rice, applesauce, toast, plain pasta 2.

Symptomatic Management

• Administer ondansetron 8 mg sublingually every 4-6 hours to facilitate tolerance of oral rehydration in patients with vomiting 2.
• Obtain a baseline ECG before ondansetron due to QTc prolongation risk 1, 2.
• Alternative antiemetics: promethazine 12.5-25 mg orally/rectally every 4-6 hours, or prochlorperazine 5-10 mg every 6-8 hours 1, 2.

Empirical Acid Suppression

Initiate omeprazole 20-40 mg once daily before meals immediately while awaiting diagnostic workup, as epigastric discomfort suggests acid-related pathology (peptic ulcer disease or functional dyspepsia) 1, 2, 5.

• Full-dose PPI therapy achieves 80-90% healing of duodenal ulcers and 70-80% healing of gastric ulcers within 4 weeks 1, 6.
• Continue for 4-8 weeks pending H. pylori test results 1, 2, 5.

Helicobacter pylori Testing and Eradication

• Test for H. pylori using ¹³C-urea breath test or stool antigen (serology is not recommended due to inferior specificity) 1, 2.
• If positive, treat with triple therapy: omeprazole 20 mg + amoxicillin 1000 mg + clarithromycin 500 mg, all twice daily for 10 days 2, 5.
• Eradication eliminates peptic ulcer mortality risk 1, 2.

Lifestyle Modifications

• Advise remaining upright for at least 2-3 hours after meals to reduce reflux symptoms 6.
• Reduce regular coffee consumption, as caffeine increases gastric acid secretion 6.
• Limit intake of citrus fruits, which commonly trigger dyspeptic symptoms 6.
• Eliminate products containing lactose and alcohol during the acute phase 2.

Red Flags Requiring Urgent Endoscopy

At age 68, this patient meets age-based criteria for consideration of endoscopy, but urgent 2-week-wait endoscopy is indicated only if any of the following alarm features develop 3, 1, 2:

• Persistent vomiting beyond 48-72 hours (a red-flag that excludes functional dyspepsia) 3, 1, 2
• Unintentional weight loss 3, 1, 2
• Dysphagia or sensation of food sticking 3, 1, 2
• Hematemesis or melena 3, 1
• Palpable epigastric mass 3
• Epigastric tenderness on examination that persists beyond initial presentation 1, 6

Follow-Up Strategy

• If symptoms resolve within 4-8 weeks, consider tapering and withdrawing PPI therapy, reserving on-demand use for recurrence 1, 6.
• Confirm H. pylori eradication with repeat stool antigen or breath test 4 weeks after completing therapy 6.
• If symptoms persist beyond 4-8 weeks despite PPI therapy, refer for non-urgent endoscopy to exclude peptic ulcer disease, gastritis, or malignancy 1, 2, 6.

Critical Pitfalls to Avoid

• Never use loperamide in cases of bloody diarrhea or fever due to risk of toxic megacolon 2.
• Do not delay endoscopy if alarm features emerge, as this can lead to missed serious pathology and poor outcomes 3, 1.
• Do not miss cardiac causes—myocardial infarction can present with isolated epigastric pain in elderly patients 1, 2, 6.
• Do not attribute persistent vomiting to functional dyspepsia without investigation, as it signals possible organic disease 3, 1, 2.