---
title: How does fluoxetine help PMDD when taken intermittently? | Niyora
description: A hypothesis suggests fluoxetine slows the breakdown of estrogen in the late luteal phase by blocking the CYP3A4 enzyme, thereby increasing estrogen levels an
url: https://niyora.com/research/papers/mechanism-of-intermittent-dosing-of-fluoxetine-in-premenstrual-dysphoric-2025/
---

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- How does fluoxetine help PMDD when taken intermittently?

Review, 2025

# How does fluoxetine help PMDD when taken intermittently?

A hypothesis suggests fluoxetine slows the breakdown of estrogen in the late luteal phase by blocking the CYP3A4 enzyme, thereby increasing estrogen levels and reducing PMDD symptoms. This theory hasn't been proven yet.

 Early or limited evidence

Review article examining fluoxetine mechanism in PMDD

## What they did

Researchers reviewed the literature to explain how fluoxetine, an antidepressant, can help PMDD when taken only on certain days, which is unusual since antidepressants typically take weeks to work. They proposed a mechanism based on how estrogen is broken down in the body.

## What they found

The authors propose that fluoxetine blocks the CYP3A4 enzyme, which normally breaks down estrogen. By slowing estrogen breakdown in the late luteal phase, fluoxetine may increase estrogen levels, thereby reducing PMDD symptoms. They suggest testing this hypothesis with CYP3A4 inhibitors like ritonavir and cobicistat.

## What it means for you

This review proposes a new explanation for how fluoxetine works in PMDD that could lead to new treatments. However, the mechanism is theoretical and hasn't been proven yet.

## About the study

Original title Mechanism of intermittent dosing of fluoxetine in premenstrual dysphoric disorder Authors Tamton T, Matadar P, Summers A et al. Journal Archives of women's mental health Year 2025 Study design Review What was tested Theoretical mechanism hypothesis (not tested) Read the paper [doi.org/10.1007/s00737-025-01610-0](https://doi.org/10.1007/s00737-025-01610-0)

## Topics

[Premenstrual dysphoric disorder (PMDD)](https://niyora.com/research/topics/condition-pmdd/)[Low mood and depression](https://niyora.com/research/topics/symptom-depression-mood/)[SSRIs and antidepressants](https://niyora.com/research/topics/treatment-ssri/)

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Calm down, see it another way, and decide what to say, with a PMS and PMDD app built by a doctor.

## Related studies

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Randomised trial, 2025

Does taking an antidepressant only during the second half of your cycle reduce anger and aggression in PMDD?

Systematic review, 2024

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Review, 2024

What are the most effective treatments for PMDD?

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