Effect of Peppermint Oil on Premenstrual Syndrome: A Randomized, Double-Blind Placebo-Controlled Study

Background: Despite the mental, physical, and behavioral problems of premenstrual syndrome (PMS) in reproductive women, there is no general agreement on effective treatment. Objectives: To determine the safety and effectiveness of herbal medicine capsules of peppermint oil as a novel formulation used for the severity management of PMS symptoms. Methods: A randomized, double-blind, placebo-controlled trial was carried out on 50 high school students who were diagnosed with PMS in Babol, Iran. The subjects were divided into two groups based on blocked randomization to receive capsules of Colpermin® containing the peppermint oil (187 mg peppermint oil/0.2 mL), or placebo twice daily for 10 days, from the 15th day of one period to the first day of the next period for two cycles. The degree of PMS was assessed using Delany’s PMS checklist with 28 items as primary, at the first luteal phase of the menstrual cycle and at the third luteal phase. Results: The PMS score was decreased for the two menstrual cycles, from 30.310.1 to 15.56.0 in peppermint oil group and from 23.27.0 to 20.78.0 in the placebo group. The mean difference of the total PMS score between the two groups was -9.77; 95% CI: -12.52 to -7.02 (P < 0.0001). The number of participants needing treatment (NNT) for the peppermint oil group was approximately two compared with that of the placebo group. Conclusions: The proposed novel peppermint oil formulation was proved to be safe and may be used as an effective treatment for reducing the severity of PMS symptoms.