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Diarrhea: Causes, Symptoms, and Home Remedies

Diarrhea is one of the most common gastrointestinal complaints that disrupts daily life. Causes range from a simple viral infection to serious inflammatory bowel disease. This guide covers types and causes of diarrhea, the risk of dehydration, effective home methods, and when to seek medical help.

March 26, 2026
Dr. Emre Gecer
1 min read

  • Osmotic diarrhea: occurs when unabsorbable osmotically active substances accumulate in the intestinal lumen. Lactose intolerance, artificial sweeteners containing sorbitol, and magnesium-containing antacids are examples. Its key feature is that diarrhea stops when the patient fasts (and thus stops taking the osmotic agent).
  • Secretory diarrhea: results from increased active fluid secretion from the intestinal mucosa. Cholera toxin, enterotoxins, and certain hormone-secreting tumors (e.g., VIPoma) act through this mechanism. Secretory diarrhea does not resolve with fasting and is typically voluminous and watery.
  • Inflammatory diarrhea: results from damage to the intestinal mucosa from infection or inflammatory disease. Dysentery (bloody diarrhea), Crohn's disease, and ulcerative colitis fall into this group. Fever, abdominal pain, and bloody-mucoid stools often accompany it.
  • Motility-related diarrhea: occurs when accelerated intestinal transit gives insufficient time for fluid absorption. Irritable bowel syndrome (IBS) and hyperthyroidism can cause this pattern.

  • Viral gastroenteritis: norovirus and rotavirus are the most common agents. Nausea, vomiting, and mild fever may accompany. Usually resolves on its own within 1–3 days.
  • Bacterial infections: Salmonella, Shigella, Campylobacter, E. coli (especially EHEC and ETEC strains), Clostridium difficile. Foodborne transmission is common.
  • Parasitic infections: Giardia lamblia, Entamoeba histolytica, Cryptosporidium. Contaminated water is the main source.
  • Medication side effects: antibiotics (especially amoxicillin–clavulanate, cephalosporins), NSAIDs, metformin, colchicine.
  • Food intolerance: the first attack of lactose, fructose, or gluten sensitivity.

  • Inflammatory bowel diseases: Crohn's disease and ulcerative colitis
  • Celiac disease: gluten-related intestinal mucosal damage
  • Irritable bowel syndrome (IBS-D): a functional disorder with no organic cause
  • Microscopic colitis: particularly in middle-aged and older women
  • Pancreatic insufficiency: oily, foul-smelling stools (steatorrhea)
  • Endocrine causes: hyperthyroidism, carcinoid syndrome, VIPoma
  • Colorectal cancer: especially when there is a persistent change in bowel habits

  • Dry mouth and thirst
  • Darker urine
  • Mild weakness

  • Marked thirst and dry mouth
  • Decreased urine output
  • Reduced skin turgor (skin returns slowly when pinched)
  • Sunken eyes
  • Dizziness and rapid heart rate

  • Very low or absent urine output
  • Confusion and lethargy
  • Low blood pressure and signs of shock
  • Increased respiratory rate
  • Cold and clammy skin

  • Milk and dairy products (temporary lactase deficiency may develop)
  • Fatty and fried foods
  • Spicy foods
  • Raw vegetables and fruits (prefer cooked forms)
  • Artificial sweeteners (sorbitol, mannitol)
  • Gas-producing foods such as beans and chickpeas
  • Alcohol and caffeinated drinks

  • Loperamide (Imodium): an antisecretory agent that slows intestinal motility. It provides symptomatic relief in mild to moderate watery diarrhea. However, it must not be used in bloody or febrile diarrhea, in children under 2, or in C. difficile infection.
  • Bismuth subsalicylate (Pepto-Bismol): has antisecretory and mild antimicrobial effects. Useful in traveler's diarrhea for prevention and treatment.
  • Antibiotics: not needed for all diarrhea. Targeted antibiotic therapy is reserved for specific bacterial infections (Shigella, Campylobacter, C. difficile, severe traveler's diarrhea). Empirical antibiotic use can promote resistance.
  • Intravenous (IV) fluid therapy: patients unable to tolerate oral intake or with severe dehydration require IV fluid replacement in a hospital.

  • Prefer bottled or boiled water
  • Avoid ice cubes
  • Stay away from undercooked food and street food
  • Choose fruits you can peel yourself
  • Practice good hand hygiene

  • Blood or mucus in the stool (dysentery)
  • High fever above 39°C
  • Diarrhea lasting more than 48 hours (24 hours in children)
  • Signs of severe dehydration (decreased urine, altered consciousness)
  • Severe abdominal pain or abdominal rigidity
  • Diarrhea that began after antibiotic use in the past 3 months (suspected C. difficile)
  • Diarrhea in immunocompromised patients
  • Chronic diarrhea with unexplained weight loss in the past 6 months
  • New change in bowel habits in patients over 50

  • Harrison's Principles of Internal Medicine, 22nd Edition — Chapter: Diarrhea and Constipation
  • Sleisenger and Fordtran's Gastrointestinal and Liver Disease, 11th Edition
  • Tintinalli's Emergency Medicine, 9th Edition — Chapter: Diarrhea
  • World Health Organization. Diarrhoeal Disease Fact Sheet, 2024
  • DuPont HL. Acute Infectious Diarrhea in Immunocompetent Adults. N Engl J Med. 2014;370:1532–1540
Dr. Emre Gecer

Dr. Emre Gecer

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İlgilendiğim bazı şeyler var. Sinema kuramı, senaryo mekaniği, sanat akımları, jazz müzik, finans teorisi, python, yapay zeka, makine öğrenmesi ve tıpın ilgimi çeken konuları gibi. Bunlar hakkında not düşebileceğim, düşüncelerimi paylaşabileceğim bir alan yaratmak istedim. Birazda hayatın içinden anlar, hikayeler eklerim diye düşünüyorum. Buranın zamanla gelişeceğine inanıyorum, belki de uzun vadede bambaşka bir şeye dönüşür. Neden olmasın?

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