Anecdotal evidence suggests that the onion extract/allantoin gel product Mederma (Merz Pharmaceuticals) might be an effective first line therapy for diminishing scars and associated symptoms.
Mederma is an onion extract gel designed to inhibit fibroblast function and proliferation, reduce scarring, offer antibacterial protection and reduce inflammation — specifically the release of histamine, leukotrienes and prostaglandin.
Ronald Friedman, M.D., a plastic surgeon based in Plano, Texas, uses the product on all his post-surgical patients, numbering about 750 patients a year, " (Mederma) reduces scar formation at the cellular level," he says.Hypertrophic, keloid scars
Amy McMichael, M.D., dermatologist and associate professor of dermatology at Wake Forest University School of Medicine, Winston-Salem, N.C., recommends over-the-counter Mederma to patients with hypertrophic and keloid scars.
She finds it useful when scars are in the active growth stage and scars are red, irritated and itchy. Surgical incision or trauma can cause these scars, she says.
"If you got a burn on Monday, by Tuesday, you would not be ready to use Mederma. You try to use it when the top layers of skin have healed over. Typically I do not like putting Mederma on open wounds because it is irritating and does not help at that stage," Dr. McMichael says.
She generally recommends that patients use it two or three times a day on the affected area. Since there is a slight film once it is applied, Dr. McMichael prescribes it once a day for patients who have visible scars on their faces or other exposed skin and more frequently if the scars are hidden. Mederma can be used under occlusion or open.
Dr. McMichael says the product often diminishes redness and irritation, and sometimes shrinks scars. When patients' scars do not shrink after using Mederma for three to six months, she uses Mederma instead as an adjunct scar revision treatment, along with a monthly or every-other-month steroid injection performed in the office.
According to Dr. Friedman, with Mederma, scars become softer and smoother — things that might happen on their own, but Mederma speeds the process and makes it more complete.
Dr. McMichael does not think Mederma is as effective in older scars. And it does not seem to be effective when used on scars resulting from post-inflammatory hyperpigmentation in people with dark skin types.
Before using Mederma, Dr. Friedman would sometimes use nothing on the scars or use silicone gel sheets or vitamin E.
"The primary difference is Mederma is inexpensive — about $15 for a 20-gram tube — I see relatively few reactions to it. Every once in a while I see someone who says it made their skin red or itchy — that might be one in 100 patients," according to Dr. Friedman.
Dr. McMichael says the product has a "peely" process and it makes a film, which some patients do not like. Otherwise, she says, it is a useful product with minimal side effects.
How it works
"No one is sure why or how Mederma works. What we think is that not only the onion skin extract works, but also the occlusion. It seems that when you occlude a new or early scar that you have a good outcome as far as shrinking that scar."
Disclosure: Merz Pharmaceuticals, manufacturers of Mederma, has sponsored Dr. McMichael to speak for another of its products. Dr. Friedman sells Mederma in his office but reports no financial ties to the company.