ONION EXTRACT – DOES IT HELP SCARS?
Onion extract is a popular ingredient in many over-the-counter scar treatments. Several studies have evaluated whether topical onion extract improves scar appearance or symptoms:
1. Scar treatments based on onion extract are no better for improving scar appearance or scar symptoms than plain petroleum gel.
2. Scar therapy with onion extract does not improve scar redness or itching.
3. There is no scientific evidence that onion extract is beneficial in improving the appearance of hypertrophic scars.
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.
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.
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.
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.
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.
Editorial note: this study shows scar treatments based on onion extract (like Mederma®) are no better for improving scar appearance or scar symptoms than plain petroleum gel.
Post surgical scars can be erythematous, raised, pruritic and painful. Numerous modalities are available to improve the appearance and symptomatology of these scars. A topical onion gel extract is the newest in the armamentarium of scar treatments. The active ingredient in this gel is allium cepa. Published studies evaluating the usefulness of this gel in the treatment of scars are not available.
To evaluate the effectiveness of topical onion gel extract in improving the appearance and symptomatology of postsurgical scars and to compare the results of its use to those of a topical emollient ointment.
Seventeen patients with surgical scars resulting from Mohs surgery were assigned to 1 of 2 groups on the day of suture removal. Each group applied a designated topical product 3 times a day for 1 month. Photographic documentation and questionnaires using a visual analog scale were completed for each scar enrolled in the study.
Using the Fischer’s exact test, no statistically significant difference between pre- and post- treatment evaluations of scar erythema and pruritus in patients using topical onion extract gel was found. A statistically significant reduction in scar erythema was found in patients using a petrolatum based ointment.
Scar hydration is an important factor in wound healing and can be achieved with topical petrolatum-based ointment. Topical onion gel extract was ineffective in improving scar erythema and pruritus in our patients.
Editorial note: this study concludes that scar therapy with onion extract does not improve scar redness or itching.
Hypertrophic scars represent an abnormal, exaggerated healing response after skin injury. In addition to cosmetic concern, scars may cause pain, pruritus, contractures and other functional impairments. Therapeutic modalities include topical medications, intralesional corticosteroids, laser therapy, and cryosurgery. Topical therapies, in particular, have become increasingly popular because of their ease of use, comfort, noninvasiveness, and relatively low cost. This review will discuss the properties and effectiveness of these agents, including pressure therapy, silicone gel sheeting and ointment, polyurethane dressing, onion extract, imiquimod 5% cream, and vitamins A and E in the prevention and treatment of hypertrophic scars.
Editorial note – The authors of this article are American dermatologists from Columbia University, Mount Sinai Hospital and the New York Medical College. On page 1028 of the article they state “In summary, despite the wide use of onion extract by patients, there is no evidence that it is beneficial in improving hypertrophic scars.”