Markland · Diseases of the colon and rectum 2015 · randomized double-blind crossover trial · n=80

Loperamide Versus Psyllium Fiber for Treatment of Fecal Incontinence: The Fecal Incontinence Prescription (Rx) Management (FIRM) Randomized Clinical Trial.

Cited 84 times in the scientific literature.

Level 2 - randomized trial

Individual randomized controlled crossover trial

PubMed 26347971 · doi:10.1097/DCR.0000000000000442 · record verified 2026-08-28

What was done

In a double-blind, placebo-controlled crossover trial at a Veterans Affairs medical center and university affiliate, 80 community-dwelling adults (mean age 60.7 ± 10.1 years; 68% men) with at least one fecal incontinence episode on a 7-day bowel diary were randomized to receive 4 weeks of daily loperamide (plus placebo psyllium powder) or psyllium powder (plus placebo loperamide capsules). Following a 2-week washout period, participants crossed over to the alternate 4-week treatment. The primary outcome was the frequency of fecal incontinence episodes recorded via 7-day bowel diaries, alongside secondary outcomes of symptom severity, quality of life, and tolerability.

What was found

Combined crossover analysis showed no statistically significant differences between loperamide and psyllium in reducing fecal incontinence episodes, symptom severity scores, or quality of life measures. Both treatments achieved within-group reductions in incontinence episodes and improvements in symptom severity and quality of life relative to baseline. However, constipation was significantly more frequent with loperamide (29% of participants) compared with psyllium (10%).

Why it matters

Bulk-forming psyllium fiber provides comparable clinical relief to loperamide for fecal incontinence while causing substantially less constipation, supporting psyllium as a better-tolerated first-line conservative option.

Limits

The study had a relatively small sample size (n = 80) and a predominantly male cohort (68%) recruited largely from a VA system, which may not generalize to typical female-predominant community populations. Additionally, the trial was limited by a short treatment duration (4 weeks per arm), potential insufficiency of the 2-week washout period, and participant attrition following the crossover phase.

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