---
title: Does open-label placebo (knowing it is placebo) help with PMS symptoms?
description: Yes, when women received placebo pills with a clear explanation of how placebos work, it reduced PMS symptoms compared to usual care and placebo without expla
url: https://niyora.com/research/papers/efficacy-of-open-label-placebos-for-premenstrual-syndrome-a-randomised-2025/
---

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- Does open-label placebo (knowing it is placebo) help with PMS symptoms?

Randomised trial, 2025

# Does open-label placebo (knowing it is placebo) help with PMS symptoms?

Yes, when women received placebo pills with a clear explanation of how placebos work, it reduced PMS symptoms compared to usual care and placebo without explanation. This shows the importance of expectation and explanation.

 Strong study design

150 women aged 18-45 years with PMS or PMDD in Switzerland

## What they did

A three-arm randomized trial in Switzerland with 150 women aged 18-45 years with PMS or PMDD. One group received usual treatment. One received open-label placebo without explanation. One received open-label placebo with a treatment explanation. All took pills for 6 weeks. Outcomes were measured over three menstrual cycles.

## What they found

At menstrual cycle 3, placebo with explanation reduced symptom intensity more than usual care (by 9.97 points, p<0.001) and more than placebo without explanation (by 6.10 points, p=0.036). It reduced symptom interference more than usual care (by 1.23 points, p=0.022) and placebo without explanation (by 1.10 points, p=0.044). 145 of 150 women (96.7%) completed the study.

## What it means for you

Placebo pills work better when combined with a clear explanation of how placebos help, even when women know they are placebos. This shows explanation and expectation matter for symptom improvement. The study was rigorous and well-completed, but it is unclear how long benefits last.

150

women randomized

145 (96.7%)

women who completed the study

6 weeks

duration of treatment

## About the study

Original title Efficacy of open-label placebos for premenstrual syndrome: a randomised controlled trial Authors Frey Nascimento A, Gaab J, Degen B et al. Journal BMJ evidence-based medicine Year 2025 Study design Randomised trial Participants 50 What was tested Open-label placebo pills with or without treatment explanation for 6 weeks versus usual care Open access Yes Read the paper [doi.org/10.1136/bmjebm-2024-112875](https://doi.org/10.1136/bmjebm-2024-112875)

## Topics

[Premenstrual syndrome (PMS)](https://niyora.com/research/topics/condition-pms/)[Premenstrual dysphoric disorder (PMDD)](https://niyora.com/research/topics/condition-pmdd/)

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