Is psyllium (Isabgol) husk appropriate for treating chronic diarrhoea after excluding underlying causes?

Psyllium (Ispaghul) Husk for Chronic Diarrhoea

Psyllium husk is appropriate and effective for treating chronic diarrhoea after excluding underlying causes, particularly for functional diarrhoea and irritable bowel syndrome with diarrhoea (IBS-D), as it improves stool consistency and viscosity through its unique water-binding properties. 1, 2

Evidence Supporting Use in Diarrhoea

Mechanism of Action in Diarrhoea

• Psyllium functions as a soluble fiber that sequesters water from liquid stools and increases the ratio of fecal solids to fecal water, thereby improving stool consistency without altering colonic motility 2
• In experimental secretory diarrhoea models, psyllium significantly increased fecal viscosity and made stools firmer in a dose-dependent manner (9-30 g/day), while other fiber types like calcium polycarbophil and wheat bran showed no effect 2
• The American Gastroenterological Association recognizes soluble fiber (including psyllium and ispaghula husk) as efficacious for treating global IBS symptoms, which commonly includes diarrhoea-predominant presentations 1

Clinical Evidence

• In pediatric chronic nonspecific diarrhoea, 87% of patients responded to treatment with psyllium (1 tablespoon twice daily), with 13 of 20 children responding specifically to psyllium after dietary modification alone failed 3
• In working dogs with chronic large-bowel diarrhoea, psyllium husk (4 tablespoons/day) decreased defecation frequency from 3.5 to 2.9 times daily, improved stool consistency in 90% of animals, and maintained beneficial effects even after discontinuation 4

Dosing Protocol for Diarrhoea

Standard Dosing

• Start with 5 g twice daily (10 g/day total), which can be titrated up to 30 g/day based on response 2, 5
• Each dose must be taken with 240-300 mL of water to prevent intestinal obstruction 5, 6
• Minimum treatment duration of 4 weeks is needed to achieve optimal benefit 5

Dose-Response Relationship

• Higher doses (18-30 g/day) produce greater increases in fecal viscosity and stool consistency in diarrhoeal conditions 2
• Unlike constipation where standard dosing suffices, diarrhoea may require the higher end of the dosing range for adequate water-binding effect 2

Critical Safety Considerations

Fluid Intake Requirements

• Inadequate fluid intake is the primary cause of intestinal obstruction with psyllium, which can occur within days of starting treatment 6
• Cases of esophageal and intestinal obstruction have been reported in elderly patients and those with pre-existing bowel narrowing 6
• Instruct patients explicitly to drink at least 240-300 mL of water with each dose 5, 6

Common Side Effects

• Flatulence is the most common side effect (standardized mean difference 0.80, CI 0.47-1.13), typically diminishing with continued use 7
• Abdominal distension may occur initially but improves as the gut microbiome adapts 7

When to Use vs. Avoid

Appropriate Scenarios

• Functional diarrhoea or IBS-D after excluding inflammatory bowel disease, infection, malabsorption, and other organic causes 1
• Chronic nonspecific diarrhoea in children after ruling out other etiologies 3
• Patients who are ambulatory and can maintain adequate hydration 5

Contraindications

• Avoid in non-ambulatory patients due to increased obstruction risk 5
• Do not use in opioid-induced diarrhoea, as it may worsen symptoms; use osmotic or stimulant laxatives instead 5
• Avoid in patients with pre-existing intestinal obstruction or strictures 6
• Use caution in elderly patients who may have difficulty maintaining adequate fluid intake 6

Long-Term Safety Profile

• Psyllium does not cause bowel dependence or tolerance, as it works through mechanical water retention rather than pharmacological stimulation of intestinal nerves 7
• Safe for continuous use without dose escalation, including throughout pregnancy 7, 8
• Does not produce colonic nerve damage or cathartic colon syndrome, unlike stimulant laxatives 7

Treatment Algorithm

1. Confirm chronic diarrhoea diagnosis by excluding underlying causes (inflammatory bowel disease, celiac disease, bile acid malabsorption, bacterial overgrowth, hormone-secreting tumors) through appropriate testing 1

2. Initiate psyllium at 5 g twice daily with 240-300 mL water per dose 5, 2

3. Titrate dose up to 15 g twice daily (30 g/day total) if response is inadequate after 2 weeks 2

4. Reassess at 4 weeks for improvement in stool consistency, frequency, and ease of defecation 5, 3

5. Continue long-term if effective, as psyllium maintains benefits without developing tolerance 7, 4