Ispaghula Husk (Fybogel) 💊
💩 Ispaghula husk (psyllium seed husk; brand names Fybogel®, Ispagel®) is a bulk-forming laxative that works by increasing stool bulk and water content.
It is gentle, well-tolerated, and safe for long-term use when combined with adequate hydration.
🧠 About
- Natural polysaccharide derived from the husks of Plantago ovata seeds.
- Acts locally within the gut — not systemically absorbed.
- Considered the most physiological and safest laxative class for chronic constipation.
- Usually effective within 2–3 days of starting therapy.
⚙️ Mechanism of Action
- Absorbs and retains water within the intestinal lumen, forming a soft, bulky gel.
- This increased bulk stretches the bowel wall and stimulates mechanoreceptors to trigger peristalsis via the enteric nervous system.
- Softens stool consistency, easing passage without causing urgency or cramps.
- Also binds bile acids and cholesterol — may modestly lower serum cholesterol with regular use.
🎯 Indications
- Chronic or functional constipation.
- Constipation in pregnancy and postpartum period (safe choice).
- Postoperative or post-anal surgery management to avoid straining.
- Irritable Bowel Syndrome (IBS) with alternating constipation and diarrhoea (regulates bowel habit).
- Adjunctive therapy for mild chronic diarrhoea (absorbs excess fluid).
💊 Dose and Administration
- Fybogel®: 1 sachet twice daily after meals.
- Ispagel Orange®: 1 sachet 1–3 times daily.
- Mix the granules in a full glass of water (at least 150–250 mL) and drink immediately before it thickens.
- Encourage the patient to drink 1.5–2 L of fluids per day to prevent obstruction.
- Effect is gradual — typically within 24–72 hours.
⚠️ Cautions and Patient Counselling
- Ensure adequate hydration, mobility, and regular access to toileting facilities.
- Do not take dry powder without fluid — risk of choking or oesophageal obstruction.
- Space doses at least 2 hours apart from other oral medications (may reduce absorption).
- May initially cause bloating or flatulence, which usually settles within a few days.
- Stop and seek medical advice if abdominal pain or vomiting develops.
🚫 Contraindications
- Intestinal obstruction or ileus.
- Stenosing bowel disease or colonic atony.
- Dysphagia or swallowing difficulty (risk of oesophageal blockage).
- Faecal impaction or severe constipation requiring disimpaction.
- Acute inflammatory or infective bowel disease (risk of perforation).
💊 Side Effects
- Common: Flatulence, abdominal distension, mild cramps.
- Rare: Gastrointestinal obstruction or impaction if taken with insufficient water.
- Very rare: Hypersensitivity reactions (rash, bronchospasm, anaphylaxis).
🧩 Comparison: Bulk-Forming vs Other Laxatives
| Laxative Type | Examples | Mechanism | Onset |
|---|
| Bulk-forming | Ispaghula husk, Methylcellulose | Absorbs water → increases stool bulk → stimulates peristalsis | 2–3 days |
| Osmotic | Macrogol, Lactulose | Draws water into bowel → softens stool | 6–24 hours |
| Stimulant | Senna, Bisacodyl | Stimulates colonic motility | 6–12 hours |
| Stool softener | Docusate sodium | Reduces surface tension → softens stool | 1–3 days |
📋 Practical Points
- Suitable for long-term use, including in older adults and pregnancy.
- Combine with dietary fibre, hydration, and physical activity for best results.
- Switch to osmotic laxatives (e.g. macrogol) if ineffective or if patient is immobile/dehydrated.
- Advise patients to maintain a regular bowel routine, ideally after meals.
📚 References
- BNF: Ispaghula Husk
- NICE CKS: Constipation in Adults (2024)
- Ford AC et al. BMJ 2014;349:g6614. “Efficacy of fibre and laxatives in chronic constipation.”
