Product Review: Mederma for Scars

Despite what all the commercials say, Mederma is not any better than petroleum jelly for improving the appearance of scars.

Manufacturer's Site


  • Won't make the scar worse


  • Expensive compared to petroleum jelly
  • Extensive marketing campaign not backed by science
  • Time intensive - manufacturer recommends applying three times a day for 8 weeks on new scars


  • The active ingredient is Allium cepa or onion extract.
  • Onion extract has been shown to have anti-inflammatory properties and to improve collagen organization in a rabbit ear model.
  • There are no human studies that show onion extract improves the appearance of scars more than petroleum jelly.

Product Review: Mederma for Scars

Scars form on the skin through a three-stage process and this process can last up to two years after an injury. Many scientists are studying this wound-healing process in an attempt to find something that will make scars less visible. It is widely recognized that wounds heal best under moist conditions -- the skin fills in faster and scars are less visible.

In 2001, a study showed that onion extract used on rabbit ear scars improved collagen organization but didn't lead to a difference in scar appearance. So far, there have been three major controlled clinical studies in the United States evaluating the effect of onion extract on human wound healing.

In all three, scars treated with onion extract did not show any improvement compared to scars treated with petroleum jelly. In fact, scars treated with petroleum jelly improved better than those treated with onion extract.

Based on these results, I do not recommend Mederma as a treatment for scars. You're probably better off just using petroleum jelly.


Shih, Richard, and Joshua Waltzman. "Review of Over-the-Counter Topical Scar Treatment Products." Plastic and Reconstructive Surgery (2007): 1091-5.

Zurada, Joanna, David Kriegel, and Ira Davis. "Topical treatments for hypertrophic scars." Journal of the American Academy of Dermatology 55(2006): 1024-31.

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