MEDERMA FOR REDUCING SCAR

Mederma is an onion-extract-based topical gel produced by Merz Pharmaceuticals of Greensboro, North Carolina. Mederma's marketing claims it can make scars "softer, smoother, and less noticeable. 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.
Though Mederma appears to do better than nothing at all, it does no better than cheap emollients which simply keep the skin moist.
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 2010 a 54-person trial 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, trademarked by Mederma as Cepalin (not to be confused with cephalin) is the active content of mederma derived from an onion called Allium cepa Linn[10], a readily available[11] and highly researched bioflavonoid with antihistamine and antiproliferative effects on both normal and malignant cells. This product is labeled as made in Germany, or originally developed in Germany.

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 reportedly been found effective in clinical trials.

ADDITION:
WHAT IS ALLANTOIN?
Allantoin is a chemical compound with formula C4H6N4O3. It is also called 5-ureidohydantoin or glyoxyldiureide. It is a diureide of glyoxylic acid. Named after the allantois, an amniote embryonic excretory organ in which it concentrates during development in most mammals except humans and higher apes, it is a product of oxidation of uric acid by purine catabolism. After birth, it is the predominant means by which nitrogenous waste is excreted in the urine of these animals. In humans and higher apes, the metabolic pathway for conversion of uric acid to allantoin is not present, so the former is excreted. Recombinant rasburicase is sometimes used as a drug to catalyze this metabolic conversion in patients. In fish, allantoin is broken down further (into ammonia) before excretion. Allantoin is a major metabolic intermediate in many other organisms including plants and bacteria.

Applications
Allantoin is present in botanical extracts of the comfrey plant and urine from cows and most mammals. Chemically synthesized bulk allantoin is nature-identical, safe, NON-TOXIC,compatible with cosmetic raw materials and meets CTFA and JSCI requirements. Over 10,000 patents reference allantoin. Manufacturers cite several beneficial effects for allantoin as an active ingredient in over-the-counter cosmetics: a moisturizing and keratolytic effect, increasing the water content of the extracellular matrix and enhancing the desquamation of upper layers of dead skin cells, increasing the smoothness of the skin; promoting cell proliferation and wound healing; and a soothing, anti-irritant, and skin protectant effect by forming complexes with irritant and sensitizing agents. It is frequently present in toothpaste, mouthwash, and other oral hygiene products, in shampoos, lipsticks, anti-acne products, sun care products, and clarifying lotions, various cosmetic lotions and creams, and other cosmetic and pharmaceutical products.

WHAT IS METHYLPARABEN?
Parabens are a class of chemicals widely used as preservatives in the cosmetic and pharmaceutical industries. Parabens are effective preservatives in many types of formulas. These compounds, and their salts, are used primarily for their bactericidal and fungicidal properties. They can be found in shampoos, commercial moisturizers, shaving gels, personal lubricants, topical/parenteral pharmaceuticals, spray tanning solution and toothpaste. They are also used as food additives.
Their efficacy as preservatives, in combination with their low cost, their long history of safe use and the inefficacy of natural alternatives like grapefruit seed extract (GSE), probably explains why parabens are so commonplace. They are becoming increasingly controversial, however, and some organizations which adhere to the precautionary principle object to their everyday use.