Mederma is a topical product used to improve scar appearance. It is a gel based on an onion extract and produced by Merz Pharmaceuticals of Frankfurt, Germany, although it is no German product nor it is sold in Germany. Mederma's marketing claims it can make scars "softer, smoother, and less noticeable". Generic versions are sold under the name cepalin.
Contents
Effectiveness
One 2006 clinical trial found no statistically significant change in hypertrophic scar appearance from products of this type compared to the standard petrolatum emollient, while a 1999 pilot trial found an onion extract gel less effective than the petrolatum.
In contrast, a 54-person trial in 2010, funded by Merz, found that an onion extract cream improved the appearance of stretch marks.
Basic research and animal testing suggest the gel could be effective. A 1996 study into the therapeutic values of onion and garlic found that they may act as an anti-inflammatory and bacteriostatic and in 2002, researchers found that Mederma improved collagen organization after injury in rabbits.
Active ingredient
Allium cepa, the common onion, is the active content of Mederma. Onions contain a readily available and highly researched bioflavonoid with antihistamine and antiproliferative effects on both normal and malignant cells.
Full ingredients
Water (purified), PEG-4, Aloe barbadensis leaf juice, Allium cepa (onion) bulb extract, xanthan gum, allantoin, methylparaben, sorbic acid, fragrance.
Similar product
Merz Pharmaceuticals also produces Contractubex for scars, which also contains onion extract in addition to other ingredients. Contractubex has been found effective in clinical trials for the prevention of hypertrophic scars and keloids in Chinese patients having laser tattoo removal.