Evaluation of Fluoxetine for Refractory Constipation With Somatic Symptom Disorder Features

The purpose of this randomized, double-blind, placebo-controlled trial is to determine whether fluoxetine is effective and safe for adults with refractory constipation that exhibits Somatic Symptom Disorder (SSD) features-namely, persistent preoccupation with bowel function, heightened perception of defecatory discomfort, and clinically significant somatic symptom burden (PHQ-15 ≥ 10) in the absence of IBS-C abdominal pain criteria. The study will address three primary questions: Efficacy-Bowel Function: • Does 12 weeks of fluoxetine increase Complete Spontaneous Bowel Movements (CSBM) and overall bowel-movement frequency compared with placebo? Efficacy-Somatic Symptom Burden: • Does fluoxetine reduce SSD severity, as measured by the Patient Health Questionnaire-15 (PHQ-15) and the Somatic Symptom Scale-8 (SSS-8)? Safety and Tolerability: • What adverse events occur during fluoxetine treatment, and how do their incidence and intensity compare with placebo?

NCT Number	NCT06506136
Lead Sponsor	Zhifeng Zhao, PhD
Conditions	Refractory Constipation, Somatic Symptom Disorder (DSM-5), Functional Constipation (FC)
Enrollment	194 participants
Start Date	2025-09-01
Primary Completion	2026-06-01 (estimated)
Study Completion	2027-05-30 (estimated)
Updated on ClinicalTrials.gov	2025-08-06