Onion Extract Gel Versus Petrolatum Emollient on New Surgical Scars: a Prospective Double-Blinded Study


Address correspondence and reprint requests to: S. Brian Jiang, MD, Beth Israel Deaconess Medical Center, 330 Brookline Ave, Shapiro-2nd FL Dermatology, Boston, MA 02215, or e-mail: bjiang@bidmc.harvard.edu.


BACKGROUND Cutaneous scars resulting from surgical procedures can be erythematous, hypertrophic, pruritic, painful, or cosmetically unacceptable. An onion extract-based topical gel (Mederma, Merz Pharmaceuticals) has been marketed as a product to improve scar appearance and texture. However, few data are available to substantiate these claims.

OBJECTIVE To compare the efficacy between the onion extract gel and a petrolatum-based emollient (Aquaphor, Beiersdorf, Inc.) in improving the appearance and symptoms of new surgical scars.

METHODS Twenty-four patients with new surgical wounds at least 4 cm in length were enrolled in the study. Using a randomized, double-blinded, split-scar study design, each scar was divided into two equal portions, and each half was assigned treatment with either onion extract gel or petrolatum ointment at the time of suture removal. Each product was applied three times daily for 8 weeks, and patients were evaluated at 2, 8, and 12 weeks following initiation of treatment. A follow-up phone interview was conducted at least 11 months postoperatively.

RESULTS Scar halves were evaluated by blinded investigators for overall cosmetic appearance, erythema, and hypertrophy. Patients also independently rated side-specific erythema, pruritus, burning, and pain. Using the paired t-test and the Wilcoxon sign-rank test, we found no statistically significant difference (p<.1) between the two treatment groups in any of the outcome variables studied.

CONCLUSION Petrolatum-based topical agents constitute standard therapy in the management of postoperative wounds. In this side-by-side, randomized, double-blinded, split-scar study, the onion extract gel did not improve scar cosmesis or symptomatology when compared with a petrolatum-based ointment.