Evaluation of Fluoxetine in Refractory Constipation Treatment

The goal of this clinical trial is to determine if fluoxetine is effective in treating refractory constipation in adults. It will also assess the safety profile of fluoxetine when used for this condition. The main questions it aims to answer are:

Does fluoxetine improve bowel movement frequency and Complete Spontaneous Bowel Movements (CSBM) in participants with refractory constipation? What adverse effects do participants experience while taking fluoxetine? Researchers will compare fluoxetine to a placebo (a look-alike substance that contains no active drug) to evaluate its efficacy and safety in treating chronic constipation.

Participants will:

Take fluoxetine or a placebo daily for 12 weeks Visit the clinic every 4 weeks for checkups and tests Maintain a diary of their CSBM, Spontaneous Bowel Movements (SBM), bowel movements, stool consistency, and any side effects experienced


Eligibility Criteria:
Inclusion Criteria:

* Meets Rome IV criteria for functional constipation or functional defecation disorder.
* Less than 3 complete spontaneous bowel movements (CSBM) per week.
* CSBM remains less than 3 times per week despite previous use of constipation medications (at least three different types) for over a month each without improvement, including osmotic laxatives, stimulant laxatives, secretagogues, biofeedback, and probiotics.
* Age between 18 and 50 years.
* Not participating in any other ongoing trials.
* Willing to participate in this trial and sign the informed consent form.
* Evaluated by a psychiatrist and found to have anxiety or depressive symptoms with an indication for fluoxetine treatment based on DSM-5 diagnostic criteria.

Exclusion Criteria:

* Constipation secondary to organic diseases (e.g., tuberculosis, polyps, Crohn's disease, tumors, congenital megacolon, pelvic floor muscle relaxation, abnormal colon transit tests), endocrine (e.g., hypothyroidism), metabolic, or neurological diseases (e.g., Parkinson's disease).
* More than one occurrence of mushy or watery stools (Bristol stool types 6 or 7) during the baseline period without the use of laxatives.
* Use of medications that may affect bowel function or induce constipation, including other laxatives, antidiarrheals, intestinal stimulants, sedatives (only the specified rescue medications are allowed during the trial, and their use should be thoroughly documented).
* History of chronic pain, substance abuse, or tobacco dependence (half a pack per day or more).
* Diagnosed mental disorders or neurological conditions, use of psychiatric medications, analgesics, or hormones, and opioid-induced constipation (OIC).
* History of allergy to psychiatric medications or fluoxetine.
* Pregnant or breastfeeding women, postpartum constipation.
* Other benign or malignant tumors, autoimmune diseases.
* Infectious diseases such as hepatitis B, hepatitis C, HIV/AIDS.
* Cardiovascular disease, coagulation disorders, or regular use of anticoagulants (warfarin and heparin), liver or kidney diseases, organ failure, cognitive impairment, aphasia, or other chronic diseases requiring long-term medication that affect quality of life and interfere with examination and treatment.