What is the recommended dosing and safety precautions for ispaghula (psyllium husk) in an adult with constipation‑predominant irritable bowel syndrome?

Ispaghula (Psyllium) for Constipation-Predominant IBS

Yes, ispaghula is psyllium husk, and it is the preferred first-line soluble fiber for adults with constipation-predominant IBS at a dose of 7–10.8 g daily, divided into 2–3 doses, with each dose mixed in 240–300 mL of water. 1

Recommended Dosing Protocol

Start with 7–10.8 g daily (equivalent to approximately 3.5 g twice daily), gradually titrating upward over 1–2 weeks to minimize bloating and gas. 1 The optimal therapeutic dose based on clinical trials is 20 g daily, though most patients achieve adequate symptom relief at 7–10.8 g daily. 2

Administration Instructions

• Mix each dose in 240–300 mL (8–10 oz) of water and consume immediately, followed by an additional glass of water. 3
• Take doses with meals or between meals, maintaining consistency in timing to establish regular bowel patterns. 1
• Continue treatment for a minimum of 4 weeks before assessing efficacy, as therapeutic benefit may require sustained use. 3

Clinical Evidence Supporting Use

The 2022 American Gastroenterological Association guidelines provide a strong recommendation for soluble fiber (specifically psyllium/ispaghula) based on meta-analysis of 15 randomized controlled trials showing improvement in global IBS symptoms with minimal adverse effects. 1 This represents the highest quality evidence available for fiber therapy in IBS-C.

Ispaghula is specifically superior to wheat bran for patients with pain, bloating, and excessive wind, producing fewer adverse effects while improving stool frequency. 1 In head-to-head trials, psyllium demonstrated significantly greater response rates than placebo (57% vs 35% at one month, 59% vs 41% at two months), while bran showed inconsistent benefit and higher dropout rates due to symptom worsening. 4

Mechanism of Therapeutic Action

Ispaghula normalizes stool consistency bidirectionally through its high water-holding capacity and gel-forming properties, making it uniquely effective for both constipation and diarrhea symptoms. 3, 5 The therapeutic benefit correlates with increased stool weight and improved bowel satisfaction rather than changes in whole gut transit time. 2, 6

Expected Outcomes and Timeline

• Improvement in global IBS symptoms and abdominal pain typically occurs within 2–4 weeks of consistent use. 1, 4
• Stool frequency normalizes with reduction in straining and improvement in stool consistency (fewer hard, pellet-like stools). 2, 7
• Bowel satisfaction improves significantly, which correlates strongly with overall well-being improvement. 6

Common Adverse Effects and Management

Flatulence is the most frequent side effect, occurring more commonly than with placebo but significantly less than with insoluble fiber (wheat bran). 3, 4 This can be minimized by:

• Starting at the lower end of the dosing range (3–4 g daily) and titrating slowly over 1–2 weeks 1
• Ensuring adequate fluid intake (minimum 240 mL per dose) 3
• Taking doses with meals to reduce gas production 1

Bloating and abdominal distension may occur initially but typically resolve with continued use and gradual dose escalation. 1, 5

Critical Safety Precautions

• Always mix ispaghula with adequate fluid (≥240 mL per dose) to prevent esophageal or intestinal obstruction. 3
• Administer at least 2 hours before or after other medications, as psyllium may reduce absorption of certain drugs. 3
• Discontinue if symptoms worsen or if no improvement occurs after 4–6 weeks of adequate dosing. 1, 4
• Ensure patients do not have dysphagia or esophageal stricture before initiating therapy, as these are contraindications to bulk-forming laxatives. 3

What NOT to Do: Critical Pitfalls

Do not prescribe insoluble fiber (wheat bran) for IBS-C, as it consistently worsens bloating, abdominal pain, and overall symptom burden. 1, 4 The 2022 AGA guidelines explicitly recommend against insoluble fiber based on evidence showing symptom exacerbation. 1

Do not start at high doses (>10 g daily) without gradual titration, as this significantly increases the risk of bloating, gas, and treatment discontinuation. 1, 3

Do not continue ispaghula indefinitely without reassessing efficacy; review response after 3 months and discontinue if no meaningful benefit is achieved. 1

When to Escalate Therapy

If symptoms persist after 4–6 weeks of optimized ispaghula therapy (20 g daily with adequate fluid intake), add polyethylene glycol (PEG) as second-line therapy. 1 If both fiber and PEG fail after 3 months, consider prescription secretagogues such as linaclotide 290 µg daily. 1, 8