Mederma is a specifically formulated herbal medication indicated for treating scars and stretch marks. This medicine contains the extract of Allium cepa (onion). Onion extract produces a powerful anti-inflammatory action on the skin, thereby reducing irritation, redness and other signs of inflammation that cause damage to the skin. Onion extract contains a chemical, Allantoin, which softens keratin in the skin and enhances the regeneration of new, healthy skin cells. It also possesses antioxidant properties that help in minimizing damage to the skin due to irritants, and reduces the chances of scar formation. These properties of generic Allium cepa have made Mederma a highly effective and safe topical medication for reducing the appearance of scars.