Background Premenstrual syndrome (PMS) has a high prevalence among women of reproductive ages but despite its high prevalence, it has no determined and absolute treatment, so far. So, the aim of the present study was to compare the effect Pimpinella Anisum (Anise) with placebo on the intensity of the symptoms of PMS. Methods The present study was a randomized double-blind controlled clinical trial. College students who were suffering from PMS and had the inclusion criteria were selected and randomly assigned into two groups of intervention (Anise) and control (placebo). Participants in the intervention group, received 110 mg capsules of Anise three times day (a total dose of 330 mg per day); the control group received similar capsules with the same dosing that contained starch. Consumption of the capsules was started 7 days before the start of the menstruation and continued until 3 days after, which was a total of 10 days during two consecutive menstruation cycles. The intensity of the symptoms of premenstrual syndrome was measured using Premenstrual Symptoms Screening Tool (PSST). To compare the intensity of the symptoms between the two study groups, generalized estimating equation statistical method was used. Results Eventually, sixty-seven 18-35 year old college students who were suffering from premenstrual syndrome were enrolled in the study. Comparing the mean score of the intensity of the syndrome between the two groups after the first and the second menstruation cycles showed a decrease in the intervention group to 13.9 (p-value<0.001; 95% CI: 16.5,-11.4) and 9.8 (p-value<0.001; 95% CI: 12.4,-7.3), respectively. Conclusion Results of the study showed that, in general, Anise was effective in decreasing the symptoms of premenstrual syndrome in comparison to placebo.
Keywords: Pimpinella anisum; Premenstrual Symptoms Screening Tool; herbal medicine; phytoestrogen; premenstrual syndrome; starch.