Mirtazapine for IBS-D: An Eight-Week Trial
Bloating & DigestionArticleSymptom responses favored treatment, but missing-data reporting limits confidence.
If mirtazapine is proposed for diarrhea-predominant irritable bowel syndrome, ask which symptom the prescriber wants to improve and how you will judge it. Bring your bowel record and medicine list. Discuss daytime alertness, appetite and weight alongside any bowel improvement.
What counted as a response?
An Iranian trial randomized 67 adults with Rome IV IBS-D to mirtazapine or placebo for eight weeks. Response meant at least a 50-point reduction on the 0–500 IBS Severity Scoring System (IBS-SSS): 21/34 taking mirtazapine versus 10/33 taking placebo responded. Eligibility required loose stools on at least three days weekly. Response was not cure. This trial cannot establish longer-term benefit.1
What weakens confidence?
The text reports 13 withdrawals, but the flow diagram lists 15. The methods describe replacing missing values with the other group’s mean, without adequately explaining implementation. These inconsistencies limit interpretation of the reported intention-to-treat results. Adverse effects caused four mirtazapine versus one placebo withdrawal. Hamadan University funded medicines and placebo.1
What should prescribing cover?
The US REMERON indication is adult major depression; IBS-D use is off-label. The label warns about sleepiness affecting driving, increased appetite and weight gain. Avoid alcohol or benzodiazepine combinations. Have the prescriber review all medicines, particularly MAO inhibitors, which are contraindicated, and other serotonergic drugs. Discuss pregnancy, breastfeeding and any history of mania.2
The boxed warning concerns increased suicidal thoughts and behavior in pediatric and young adult patients; monitoring applies to everyone taking an antidepressant. Contact the prescriber immediately about suicidal thoughts or abrupt concerning mood changes. If stopping is appropriate, agree a gradual reduction rather than stopping suddenly.2
The AGA’s 2022 IBS-D recommendations include rifaximin, loperamide and other options; its antidepressant recommendation concerns tricyclics. That recommendation does not establish benefit for every antidepressant. Ask how this proposed treatment fits your previous care, which alternatives fit your symptoms and what would trigger reassessment.3
Bloated by Dinner includes “The Visit Script”: bring a bowel-and-symptom pattern, list medicines and supplements, and ask what has been ruled out and what comes next. Record bowel changes separately from alertness and weight so the follow-up can consider each concern.
Discuss treatment with your prescriber. Do not change medicines based on trial doses.
Girl Playbook sells this book. It provides education and worksheets, not individualized medical care.
Sources
The research behind this article, in the order it’s cited. How we source our articles.
- Khalilian and colleagues, 2021Mirtazapine versus placebo for diarrhea-predominant IBS (opens in a new tab)ab
- Organon, DailyMed, Revised November 2021REMERON: US prescribing information (opens in a new tab)ab
- American Gastroenterological Association, 2022Pharmacological management of IBS with diarrhea (opens in a new tab)↩
Spotted something out of date? Tell us and we’ll check it.
