Written By: IJCP Editorial Team

Published On: 16 Apr, 2025 12:12 PM | Updated On: 25 Apr, 2025 1:19 PM

Effectiveness and Safety of Open-Label Placebos in Treating Premenstrual Syndrome

The current study was designed to assess the effectiveness and safety of open-label placebos (OLP) for treating premenstrual syndrome (PMS).

The study was a randomized controlled trial conducted from 2018 to 2020. The trial involved 150 women aged 18 to 45 diagnosed with PMS or premenstrual dysphoric disorder. Participants were randomly assigned (1:1:1) to one of three groups: treatment as usual (TAU), OLP without treatment rationale (OLP–), or OLP with treatment rationale (OLP+). Participants in the OLP groups received two placebo pills daily for six weeks. The primary outcomes were the intensity of PMS symptoms and their impact on daily life measured over three menstrual cycles (MC1–MC3). Safety was evaluated through adverse events reported at weeks 3 and 6. Secondary outcomes included psychological and physical aspects of symptom intensity and adherence to treatment.

The results demonstrated:

• A total of 150 women were equally divided among the three groups, with 145 (96.7%) completing the trial.
• Significant differences were found in symptom intensity (F(4)=4.419, r2=0.16) and interference (F(4)=3.159, r2=0.13) across the menstrual cycles.
• At MC3, the OLP+ group showed a significantly lower symptom intensity compared to both TAU (b=–9.97, SE=2.85, d=0.90) and OLP– (b=–6.10, SE=2.89, p=0.036, d=0.55), while there was no significant difference between OLP– and TAU (b=–3.87, SE=2.87, d=0.35).
• Interference at MC3 was also lower in the OLP+ group compared to TAU (b=–1.23, SE=0.54, d=0.55) and OLP– (b=–1.10, SE=0.54, d=0.48), with no difference between OLP– and TAU (b=–0.14, SE=0.54, d=0.06). 
• Four mild adverse events were reported: one in the OLP– group and three in the OLP+ group. 
• Improvements in psychological and somatic symptoms were similar to the primary outcomes, and adherence to the OLP intervention was high at 93.18±18.95%, with no differences noted among groups.

The findings from this clinical trial suggest that OLP provided with a treatment rationale is an effective, safe, and well-accepted option for managing PMS.

Source: Frey Nascimento A, Gaab J, Degen B, Rytz M, Holder A, Sezer D, Buergler S, Meyer AH, Kirsch I, Kossowsky J, Locher C. Efficacy of open-label placebos for premenstrual syndrome: a randomised controlled trial. BMJ Evid Based Med. 2025 Mar 25:bmjebm-2024-112875. doi: 10.1136/bmjebm-2024-112875. Epub ahead of print. PMID: 40132912.