Stretch marks, also called striae, develop when skin is continuously stretched as a result of weight gain, growth spurts or pregnancy. Stretch mark creams can't prevent, or completely remove, stretch marks, but they can improve their appearance by reducing discoloration and improving skin texture. The ingredient lists for over-the-counter stretch mark creams begin with purified water. Otherwise comparisons are difficult because some have fewer than 20 ingredients and others have 40 or more.
Onion Extract
A study in the June 2008 "Journal of Cosmetic Dermatology" concluded that onion extract gel improved the redness, texture and softness of surgical scars. Since stretch marks are a type of scar tissue, one product on the market uses onion extract (allium cepa) together with hyaluronic acid, which is naturally found in the skin where it helps repair tissue and hydrates the skin.
Palm, Wheat Germ, Sesame Seed and Mineral Oils
Wheat germ, palm and sesame seed oils contain vitamin E, and they're high in naturally emollient fats. Vitamin E (tocopherol) is an antioxidant found in skin, and it's used in creams to diminish scars. However, its effectiveness when applied topically has not been substantiated by research. Mineral oil, the primary ingredient in baby oil, is used as a skin ointment and to reduce inflammation.
Cocoa Butter
Cocoa butter is a fat made from the cacao bean, which is the basis for chocolate. The August 2008 "British Journal of Obstetrics and Gynaecology" reported that cocoa butter did not reduce the likelihood of developing stretch marks during pregnancy. However, cocoa butter has emollient properties that help restore moisture to the skin.
Shea Butter
Shea butter is a natural fat from the African shea tree. According to the American Shea Butter Institute, it is an excellent moisturizer that's easily absorbed by the skin and contains vitamins A and E. The Institute states that vitamin A helps improve wrinkles, eczema, burns and dermatitis, but the effects of vitamin E are uncertain.
Collagen
Collagen is a protein that forms the supporting connective tissue of the skin. Collagen is injected under the skin to temporarily remove wrinkles, but it's not readily absorbed by skin. As a result, its use in a topical cream is limited.
Chemicals
Many of the chemicals found at the top of the ingredient lists, such as cyclopentasiloxane, butylene glycol, arachidyl alcohol, alkyl benzoate and cetearyl alcohol, are emollients, humectants, solvents, stabilizers and surfactants. Emollients soften and sooth skin. Humectants are moisturizing agents that work by absorbing and retaining moisture. Solvents and stabilizers ensure that the ingredients mix together. Surfactants reduce surface tension, which makes the cream easier to spread over the skin.
Glycerin and Lanolin
Glycerin, or glycerol, is one of the natural components of fatty acids. It functions as a moisturizer and is frequently used to heal skin conditions. Lanolin is a fatty substance that comes from wool-bearing animals. It's used as an ointment to treat dry skin. It can also help carry other chemicals through the skin.
Peptides
Peptides can be found under various names, including palmitoyl oligopeptide and palmitoyl pentapeptide. They're amino acids that stimulate the production of collagen.
