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Loose motions plus stomach pain

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Here is a comprehensive overview of loose motions (acute diarrhea) with stomach pain, based on Harrison's Principles of Internal Medicine and Sleisenger & Fordtran's GI and Liver Disease.

Acute Diarrhea with Abdominal Pain

What Is It?

Diarrhea lasting <2 weeks is considered acute. More than 90% of cases are caused by infectious agents (bacteria, viruses, parasites) and are often accompanied by vomiting, fever, and abdominal pain. The remaining ~10% stem from medications, toxic ingestions, ischemia, or food-related causes.

Common Causes

Infectious (most common):
SourceLikely Pathogen
Undercooked chickenSalmonella, Campylobacter, Shigella
Undercooked hamburgerE. coli O157:H7
Fried/reheated riceBacillus cereus
Mayonnaise/creamsStaphylococcus aureus, Salmonella
Raw seafoodVibrio, hepatitis A
Travel abroadE. coli (enterotoxigenic), Campylobacter, Giardia, norovirus
Recent antibioticsClostridioides difficile
Non-infectious causes:
  • Medications (laxatives, antibiotics, NSAIDs, metformin)
  • Irritable bowel syndrome (IBS) flare
  • Inflammatory bowel disease (IBD — Crohn's/UC)
  • Ischemic colitis (especially in older adults)
  • Food intolerance (lactose, gluten)

Red Flag Symptoms — Seek Medical Attention

Evaluation is warranted if any of the following are present:
  • Profuse diarrhea with signs of dehydration (dry mouth, no urination, dizziness)
  • Bloody or black stools
  • Fever ≥38.5°C (101°F)
  • Duration >48 hours without improvement
  • Recent antibiotic use
  • Severe abdominal pain, especially if aged >50
  • Elderly (≥70 years) or immunocompromised patients

Management Algorithm

Algorithm for management of acute diarrhea

Treatment

1. Fluids first — most important step
  • Oral rehydration is the cornerstone: use ORS (oral rehydration solution), sports drinks, or coconut water
  • Sip frequently even if nauseous
  • Severely dehydrated patients (especially infants, elderly) need IV fluids
2. Antidiarrheal medications (mild–moderate, non-febrile, non-bloody)
  • Loperamide (Imodium) — reduces stool frequency; do not use if fever or bloody stools (can worsen bacterial dysentery)
  • Bismuth subsalicylate (Pepto-Bismol) — helps nausea and diarrhea; avoid in immunocompromised or renal impairment
3. Antibiotics (only when indicated)
  • Empirical for moderate-to-severe febrile diarrhea:
    • Azithromycin 500 mg single dose, or
    • Ciprofloxacin 500 mg twice daily × 3–5 days
  • Suspected Giardia: Metronidazole 250 mg 4×/day × 7 days
  • C. difficile: requires specific targeted therapy
4. Diet
  • Continue eating if tolerated — the old "starve a fever" approach is outdated
  • BRAT diet (Banana, Rice, Applesauce, Toast) helps settle the stomach
  • Avoid dairy, caffeine, alcohol, and fatty/spicy food temporarily
  • Probiotics may shorten duration slightly

When to Go to a Doctor

  • Diarrhea lasting >2–3 days with no improvement
  • Blood in stool
  • High fever
  • Signs of dehydration (not urinating, confusion, extreme weakness)
  • Symptoms in a child under 2, elderly person, or immunocompromised individual
Disclaimer: This information is educational and not a substitute for professional medical advice. If symptoms are severe or persistent, please consult a healthcare provider.
— Harrison's Principles of Internal Medicine 22E, Chapter 49 | Sleisenger and Fordtran's GI and Liver Disease, Chapter 16
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