Placebos appear to reduce PMS symptoms

Women affected by premenstrual syndrome (PMS) appear to experience less intense and debilitating symptoms after taking placebo pills even when told they do not contain any active medication, according to a study published in BMJ Evidence-Based Medicine.

PMS can result in significant distress for women of reproductive age and cause psychological symptoms such as irritability and mood swings, as well as physical symptoms including breast tenderness, bloating and joint pain. Furthermore, medical treatments to help with PMS, such as selective serotonin reuptake inhibitors (SSRIs) and hormonal agents like oral contraceptives, are often associated with side effects including dizziness, nausea, tremor, weight gain, gastrointestinal symptoms and depression.

Open-label placebos (OLPs) — placebos that are provided with full transparency — have been shown to have positive effects on various complaints, including irritable bowel syndrome, chronic low back pain and menopausal hot flushes. With this in mind, a research team led by the University of Basel set out to examine whether OLPs could have a positive impact on PMS symptoms.

The team carried out a trial involving 150 women aged 18 to 45 years old who had PMS or premenstrual dysphoric disorder. Between August 2018 and December 2020, the participating women were randomly allocated into three groups to either receive treatment as usual, receive OLPs with no further explanation than that they were receiving placebos, or receive OLPs with an explanation of what they were and why they could potentially ease PMS symptoms.

Regarding the study’s primary outcomes, placebos provided twice a day for six weeks with an explanation resulted in a 79.3% reduction in symptom intensity and an 82.5% reduction in interference in participants’ social, educational and working lives. Those receiving a placebo with no explanation meanwhile reported a 50.4% reduction in the intensity of their symptoms and a 50.3% drop in interference in their lives. In contrast, women who received treatment as usual reported a 33% reduction in their symptom intensity and a 45.7% reduction in interference in their lives.

For secondary outcomes, women in the placebo with explanation group had the highest decrease (70.7%) in psychological symptom intensity between menstrual cycles, followed by the placebo with no explanation group at 42.6% and the treatment as usual group at 29.1%. Women in the placebo with explanation group also reported the highest reduction (82.5%) in physical symptom intensity between menstrual cycles, followed by women in the placebo with no explanation group (50.3%) and women in the traditional treatment group (45.7%).

There were very few side effects amongst women in both placebo groups, none of which were serious.

The authors acknowledged that when they advertised the trial as a study for a side-effect free intervention for PMS, they might have attracted participants who were more open to unconventional treatments and/or being dissatisfied with their current treatment, which could have limited how much the results were generalisable. Also, the results were reliant on self-reporting so this could bias the results.

Nevertheless, the researchers concluded that administering OLPs to women with PMS can decrease symptom intensity and interference considerably in the absence of substantial side effects, and with full transparency. OLP treatment could thus serve as an acceptable, efficacious and safe intervention for PMS.

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