Merz Pharmaceuticals claims the over-the-counter onion extract gel, Mederma, improves the appearance and texture of surgical scars(5). Mederma states that it works for many types of scars, including acne scars, surgery scars, and scars from burns, cuts, and other injuries. Mederma has not been FDA approved a study is referenced on the website that states Mederma is (7).
Onion extract (Allium cepa) contains several bioflavenoids (quercitin, kaempferal and cepalin), metalloporteinases and thiosulfates(2). In vitro studies, suggest that onion extract has anti-inflammatory, antiproliferative, bacteriostatic and collagen down regulatory properties by its effect on fibroblast and mast cells (2,12). In theory, each of these components should be beneficial to wound healing, although clinical studies have been unsatisfactory (12)
Draelos et al. (2011) conducted a randomized, controlled, single-blind study for 8 week comparing the use of Mederma Advanced to no treatment. The study included 44 subjects, 39 of which were Caucasian, 4 African American and 1 Hispanic. An exclusion criterion was history of hypertrophic or keloid scarring. The wounds treated in the study were a result of the shaving of seborrheic keratoses, one on either side of the chest wall. The wounds were treated with topical bacitracin and bandaged for 2 weeks. At this point each subject was randomly assigned to a group. The first group applied once-daily onion extract gel to the right scar and applied nothing to the left scar. The second group applied once-daily onion extract to the left scar and applied nothing to the right scar. (2)
Follow up visits were conducted at week 4, 6 and 10 weeks. At these times the wounds were examined by the investigators and subjects. Two of the subjects had no data for week 10, the values were imported using LOCF (Last Observation Carried Forward). The wounds were graded on overall appearance, texture, redness and softness using ordinal scales (0=no change, 1=mild improvement, 2= moderate improvement, 3=significant improvement). The results of this study stated there was no statistically significant difference in scar height but there was a statistical difference in texture, redness, softness, and overall appearance as assessed by the investigators. (2)
A study to analyze the efficacy of Mederma in the Asian population was performed in 2012 by Vachiramon et al. The study was a prospective, randomized, double-blinded, split-scar study including 16 postpartum Thai women aged 19-34. These women began the 12 week treatment 7 days after undergoing a cesarean section for the first time. The sutures used for the surgery were absorbable. Half of the scar received vehicle-based gel and the other half received a 12% Allium cepa gel with 1cm in the middle left untreated. The gels were applied three times daily for 12 weeks. (12)
The wounds were assessed using objective and subjective evaluations at baseline, 4th and 12th weeks. The...