Diarrhoea

• Diarrhoea


  An increase in frequency of passage of soft or watery stools relative to the usual bowel habit for that individual
• The WHO defines diarrhoea as the passage of three or more loose or liquid stools per day
• Diarrhoea


  Not a disease but a sign of an underlying problem, e.g. an infection or gastrointestinal disorder
• Types of diarrhoea


  • Acute (lasting less than 14 days)
  • Persistent (lasting 14 days or more)
  • Chronic (lasting longer than a month)
• The exact prevalence and epidemiology of diarrhoea are not well known, which could be due to the number of patients who don't seek care, wait for the problem to resolve naturally or who self-medicate
• Acute diarrhoea is very common and it has been reported that children under the age of 5 have between one and three bouts of diarrhoea per year and adults, on average, just under one episode of diarrhoea per year
• Causes of diarrhoea


  • Acute gastroenteritis (usually viral in origin, including rotaviruses and noroviruses)
  • Bacterial causes (e.g. Enterotoxigenic Escherichia coli, Enteropathogenic E. coli, Enteroinvasive E. coli, Shigella, Salmonella, Staphylococcus aureus, Bacillus cereus)
  • Protozoa (e.g. Giardia lamblia, Entamoeba histolytica)
• Viruses


  Tend to cause diarrhoea by blunting the villi of the upper small intestine, decreasing the absorptive surface
• Bacterial causes


  Normally a result of eating contaminated food or drink, which cause diarrhoea by a number of mechanisms
• Mechanisms of bacterial diarrhoea

  • Enterotoxigenic Escherichia coli produces enterotoxins that affect gut function with secretion and loss of fluids
  • Enteropathogenic E. coli interferes with normal mucosal function
  • Enteroinvasive E. coli, Shigella and Salmonella spp. cause injury to the mucosa of the small intestine and deeper tissues
  • Other organisms (e.g. Staphylococcus aureus and Bacillus cereus) produce preformed enterotoxins, which on ingestion stimulate the active secretion of electrolytes into the intestinal lumen
• Causes of persistent diarrhoea

  • Protozoa (e.g. Giardia lamblia, Entamoeba histolytica)
• Pathophysiology of diarrhoea


  • Increase in osmotic load in gut lumen
  • Increase in secretion
  • Inflamed intestinal lining
  • Increase in intestinal motility
• Non-infective causes of diarrhoea

  • Anxiety
  • Alcohol
  • Food allergies
  • Coffee
  • Sweets (high sorbitol content)
  • Medication (laxatives, antibiotics, chemotherapy, magnesium, metformin)
• Causes of chronic diarrhoea

  • IBS
  • Diet
  • IBD
  • Microscopic colitis
  • Coeliac disease
  • Malabsorption (e.g. lactose intolerance)
  • Cancer
  • Faecal impaction
• Symptoms of acute diarrhoea

  • Passing frequent, soft, watery stools (relative to usual habit)
  • Nausea and vomiting
  • Abdominal cramping, flatulence, and tenderness
  • Viral prodromal symptoms (e.g. cough, cold) if caused by rotavirus
  • Watery nature with no blood present
  • Fever and loss of appetite
• Acute diarrhoea usually clears up in a couple of days: viral is 2-3 days; untreated bacterial is 3-7 days and protozoal is weeks to months without treatment
• Chronic and recurrent diarrhoea should be referred
• Dietary advice for diarrhoea

  • Eat when you feel able to
  • Small, light meals with plain foods if possible to start with, e.g. wholemeal bread, rice etc
  • Avoid fruit juice or fizzy drinks
  • Historically avoid dairy
  • Continue to breastfeed or bottle feed as normal (do not dilute formula milk)
  • Drink plenty of fluids to avoid dehydration
  • Drink small sips of water often
  • Avoid fatty, spicy, heavy food
• Hygiene advice for diarrhoea

  • Stay off school/work for at least 48 hours after last episode of diarrhoea
  • Wash hands with soap and water frequently
  • Wash contaminated clothing/bedding separately on a hot wash
  • Clean toilet seats, flush handles, taps, touched surfaces daily etc
  • Do not prepare food for other people
  • Do not share towels, utensils etc
  • Do not use a swimming pool until 2 weeks after symptoms stop
• Oral rehydration therapy (ORT)

  Glucose and electrolytes, e.g. dioralyte, to replenish fluids and salts
• ORT should be first-line, especially for children
• OTC age restriction for ORT is 1 year and above
• Loperamide


  First choice after ORT if rapid control of symptoms is needed, slows small and large intestine transit by decreasing bowel motility through action on opioid receptors in gut, thus can increase absorption of fluid and electrolytes
• Loperamide is for over 12 years old
• Loperamide dosage


  Take two capsules initially, followed by one capsule after each loose stool, maximum of 16mg per day
• Other anti-diarrhoeal medications


  • Adsorbents (e.g. kaolin, charcoal)
  • Kaolin and Morphine
  • Bismuth-containing products (e.g. bismuth subsalicylate)
  • Bulk-forming agents
• Adsorbents (e.g. kaolin, charcoal) have little therapeutic use as they could still lead to fluid loss from the bowel
• Kaolin and Morphine is for over 12 years old
• Bismuth-containing products are for over 16 years old and can cause blackened stools and tongue as a side effect
• Bulk-forming agents


  May be useful in conditions with chronic diarrhoea e.g. IBS, as they may adsorb water to create a formed stool
• Referral criteria for diarrhoea

  • Duration longer than 2-3 days in children and older adults — at risk of dehydration and associated complications
  • Patients unable to drink fluids
  • Diarrhoea following recent travel to tropical or subtropical climate — possible giardiasis
  • Change in bowel (long-term) habit in patients 40 years — possible sinister pathology
  • Presence of blood or mucus in the stool
  • Suspected faecal impaction in older adults — outside scope of community pharmacist
  • Steatorrhoea (too much fat in stool) — possible malabsorption syndrome
• Advise patients to come back if symptoms persist more than 4-5 days or signs of dehydration appear