The Effect of Evening Primrose (Oenothera biennis) Oil Capsule on Postpartum Pain in Multiparous Women: A Triple-Blind Randomized Clinical Trial

Postpartum pain is a problem of women after delivery, which increase in multiparous women. Due to the side effects of chemical drugs to control postpartum pain and the individuals' tendency to use herbal medicine, the present study aimed to investigate the effect of evening primrose (Oenothera biennis) oil capsule on postpartum pain in multiparous women.

This triple-blind randomized clinical trial examined 90 multiparous women two hours after a normal vaginal delivery, who had a moderate to severe postpartum pain at maternity ward of Ommolbanin Hospital, Mashhad, Iran in 2021. The participants were randomly assigned to three groups including intervention, placebo, and control group. A capsule of evening primrose oil or placebo was given to the subjects every 8 hours for up to 4 doses. The control group received routine medication (acetaminophen). Pain severity was measured one hour before and after each intervention using the Visual Analogue Scale (VAS), and McGill Pain Questionnaire. Data analysis was carried out by Kruskal-Wallis, one-way analysis of variance (ANOVA), Chi-square and exact Chi-square tests using SPSS software (Ver. 16).

The mean severity of postpartum pain after intervention in the group received evening primrose oil capsule had a significant decrease versus placebo and control groups (P <0.001) and no side effects in the intervention group was observed.

Evening primrose oil was effective in reducing the severity of postpartum pain in multiparous. So it seems that it could be recommended as a safe medication for postpartum pain relief in multiparous women.