Fake pills ease PMS symptoms even when you know they’re placebos
Women with premenstrual syndrome reported big improvements in their symptoms after taking placebo pills, despite knowing they did not contain any active ingredients
By Carissa Wong
25 March 2025
Placebo pills can have real effects through the power of suggestion
SeventyFour Images / Alamy
Women with premenstrual syndrome seem to benefit from the placebo effect even when they know they are taking sham pills, suggesting this could provide a cheap and easy treatment.
Premenstrual syndrome (PMS), which involves symptoms such as anxiety, mood swings and abdominal cramps, commonly affects anyone who has periods. Previous studies have found that placebo pills can reduce symptoms in women who think they may be taking a real medication, but it was unclear whether these benefits remain when people knowingly take sham pills.
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Antje Frey Nascimento at the University of Basel in Switzerland and her colleagues recruited 150 women in Switzerland aged 18 to 45 who had moderate to severe PMS. In a survey that scored 27 PMS symptoms on a scale of 0 to 5, the participants rated at least one symptom a 4 or a 5 at the start of the study. The participants also reported that at least one symptom interfered with their social, work or school lives, scoring this disruption a 4 or a 5.
Next, the researchers randomly assigned one-third of the participants to take two placebo pills daily over two menstrual cycles, and told these people they were taking placebos. Another third of the participants also took placebo pills, but they received an additional explanation of how placebos can relieve symptoms through the power of suggestion and belief.
The remaining third of participants were not given placebos, but all groups were able to take their normal medications. All the participants completed daily surveys on their PMS symptoms and how much these interfered with their lives.
