Effect of evening primrose oil on postoperative pain after appendectomy: A double-blind, randomized, clinical trial

Despite advances in surgical techniques and pharmacology, postoperative pain remains a common problem after appendectomy, and its management continues to be suboptimal. The aim of this study was to evaluate the effect of evening primrose oil on the reduction of postoperative pain after appendectomy.

In a double-blind, randomized, clinical trial, a total of 80 adults patients with acute appendicitis who were undergoing appendectomy at the Shahid Beheshti Emdad Hospital in Sabzevar, were included. Patients were randomly allocated into two equally sized groups (n = 40). In postoperative period and after recovering from the anesthesia, each of the intervention and control groups received one evening primrose (1000 mg) or placebo capsules every 30 min for 3 times, respectively. All patients in both groups were asked to rate the intensity of their pain on a 0-10 point Visual Analogue Scale (VAS) and also McGill pain questionnaire, before and 1 h after the last administration of the drug, postoperatively.

In patients who received evening primrose, both VAS and McGill pain intensity scores significantly decreased after intervention, when compared prior to initiation of the intervention (p < 0.0001). While in the control group, changes of pain intensity scores were not significantly different before and after the intervention (p > 0.05).

It seems that oral evening primrose can be used as a simple and safe potential adjunctive treatment for postoperative pain control after appendectomy.