Diarrhoea: Causes, Symptoms, and Treatment

Diarrhoea means having loose or watery bowel movements more often than usual. It's usually caused by infections from viruses, bacteria, or parasites, but can also result from food intolerances or medications. The main treatment is drinking plenty of fluids to prevent dehydration. See a doctor if symptoms last more than 2 days or if you notice signs of dehydration like dizziness or minimal urination.

In plain words

Diarrhoea means having loose or watery bowel movements more often than usual. It is usually caused by infections from viruses, bacteria, or parasites. It can also happen because of food intolerances or certain medicines. The main treatment is drinking plenty of fluids to stay hydrated. See a doctor if symptoms last more than 2 days or if you feel dizzy or pee very little.

What is Diarrhoea: Causes, Symptoms, and Treatment?

Diarrhoea means having loose or watery bowel movements more often than usual. It's usually caused by infections from viruses, bacteria, or parasites, but can also result from food intolerances or medications. The main treatment is drinking plenty of fluids to prevent dehydration. See a doctor if symptoms last more than 2 days or if you notice signs of dehydration like dizziness or minimal urination.

Symptoms

Early symptoms

  • Loose or watery stools: Bowel movements become less solid and more liquid than usual. You may need to go more frequently than your normal pattern. (3)
  • Abdominal cramps: Pain or discomfort in the stomach area that may come and go with bowel movements. (3)
  • Urgency to use the toilet: Sudden strong need to have a bowel movement that may be difficult to control. (3)
  • Bloating: Feeling of fullness or swelling in the abdomen. (3)
  • Nausea: Queasy feeling that may or may not lead to vomiting. (3)
  • Mild fever: Slightly elevated temperature, especially with infectious causes. (3)

Serious or emergency symptoms

  • Blood or mucus in stool: Red streaks or black tarry appearance indicates possible serious infection or intestinal bleeding. Seek urgent medical care. (4)
  • Signs of severe dehydration: Sunken eyes, dry mouth, dizziness when standing, little or no urination for 8+ hours, or extreme thirst. Get medical help immediately, especially for babies or elderly. (8)
  • High fever (above 102°F/39°C): Suggests possible serious infection needing medical evaluation. Contact your healthcare provider. (4)
  • Persistent vomiting: Unable to keep fluids down for more than 24 hours, increasing dehydration risk. Seek medical attention. (8)
  • Severe abdominal pain: Pain that doesn't ease with bowel movements could indicate serious conditions. Requires urgent evaluation. (4)

Causes

Primary causes

  • Viral infections: Norovirus, rotavirus (common in children), and other viruses are frequent causes, especially with accompanying vomiting. (1)
  • Bacterial infections: Salmonella, E. coli, Campylobacter from contaminated food or water cause more severe cases often with fever. (1)
  • Parasites: Giardia and Cryptosporidium from unclean water can cause persistent diarrhoea with bloating. (5)
  • Food intolerances: Lactose intolerance and other digestive enzyme deficiencies lead to diarrhoea after consuming trigger foods. (5)
  • Medications: Antibiotics commonly disrupt gut bacteria balance. Other drugs like magnesium-containing antacids may also cause it. (5)

Risk factors

Young age

Children under 5, especially in developing countries, have higher rates due to developing immune systems and exposure risks. (6)

Travel to developing regions

Higher risk of exposure to contaminated food/water. 'Traveller's diarrhoea' often stems from E. coli strains. (7)

Weakened immune system

HIV/AIDS patients and those on immunosuppressants face more severe and prolonged diarrhoea episodes. (6)

Poor sanitation

Lack of clean water and proper hygiene facilitates faecal-oral pathogen transmission. (6)

Diagnosis

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Treatment

Medication options

Oral rehydration solutions

Replaces lost fluids and electrolytes more effectively than water alone, especially important for children. (5)

Antimotility agents

Slows intestinal movement to reduce stool frequency, providing symptomatic relief for adults. (5)

Antibiotics (when indicated)

Only effective for confirmed bacterial infections like Campylobacter or Shigella, not routine cases. (5)

Lifestyle and self-care

  • Fluid replacement: Sip small amounts of ORS, diluted fruit juice, or broth frequently. Avoid alcohol, caffeine, and sugary drinks that worsen fluid loss. (2) (3)
  • Gradual food reintroduction: Start with bland, easy-to-digest foods like bananas, rice, applesauce, or toast when appetite returns. Eat smaller portions more frequently. (3)
  • Probiotics: May help restore gut bacteria balance, especially after antibiotic-associated diarrhoea. Evidence is mixed for other causes. (3)
  • Hand hygiene: Thorough handwashing with soap after toilet use and before food preparation prevents spreading infectious causes to others. (2)

Always discuss dosing and treatment changes with your own prescriber.

Possible complications

  • Dehydration: The most serious risk, especially for infants and elderly. Can lead to electrolyte imbalances, kidney problems, or shock if untreated. (6)
  • Nutritional deficiencies: Persistent diarrhoea may impair nutrient absorption, concerning for growing children. (6)
  • Febrile seizures: In young children with high fever from certain infections. (6)
  • Reactive arthritis: Rare complication following some bacterial infections causing joint pain and swelling. (6)

When to see a doctor

Routine follow-up

  • See your doctor if diarrhoea lasts more than 2 days in adults or 24 hours in children, or if accompanied by fever above 102°F (39°C). (2)
  • Infants under 6 months with diarrhoea should always be evaluated promptly due to rapid dehydration risk. (8)

Seek emergency care

  • Seek emergency care for signs of severe dehydration: dizziness when standing, minimal/no urination for 8+ hours, sunken eyes, or confusion. (4)
  • Get immediate medical attention if you notice bloody or black/tarry stools, which may indicate serious infection or bleeding. (4)

Frequently asked questions

What should I eat when I have diarrhoea?

Start with small amounts of bland foods like bananas, white rice, applesauce, or toast when you feel able. Avoid fatty, spicy, or very sweet foods until recovered. Most important is staying hydrated with small frequent sips of fluids. (3)

How can I tell if my baby is dehydrated?

Watch for fewer wet diapers (less than 1 every 6-8 hours), no tears when crying, dry mouth, sunken soft spot on head, or unusual sleepiness. These signs require immediate medical evaluation. (8)

Can stress cause diarrhoea?

Yes, the gut-brain connection means anxiety can trigger loose stools or urgency in some people, though typically temporary. Persistent stress-related digestive issues may indicate IBS and warrant medical discussion. (3)

What's the difference between food poisoning and diarrhoea?

Food poisoning is one cause of diarrhoea, usually from bacteria like Salmonella. It often includes vomiting and starts suddenly 2-6 hours after eating contaminated food. Diarrhoea describes the symptom itself, which has many causes. (1)

Should I take probiotics for diarrhoea?

Some research suggests certain probiotic strains may modestly shorten infectious diarrhoea, especially in children. Evidence is strongest for antibiotic-associated diarrhoea prevention. Ask your doctor before using. (3)

References

  1. CDC — Diarrhea: Common Illness, Global Killer source 1
  2. CDC — Treatment for Diarrhea source 2
  3. NHS — Diarrhoea source 3
  4. NHS — Diarrhoea and vomiting source 4
  5. MedlinePlus — Diarrhea source 5
  6. WHO — Diarrhoeal disease source 6
  7. CDC — Travelers' Diarrhea source 7
  8. NHS — Diarrhoea and vomiting in babies source 8