It takes commitment to apply stretch mark cream two to three times daily over the course of several months. So if it doesn't really work, wouldn't you like to know before buying one?

"Stretch mark creams containing ingredients like alpha hydroxy acids combined with retinol (or vitamin A), cayenne pepper, tiger's herb, vitamin C — anything that encourages collagen or elastin (elastic tissue) production and circulation — can help," says dermatologist Dr. Howard Murad, MD.

With that in mind, our testers tried three popular stretch mark creams for eight weeks, none of which made stretch marks vanish (even the packaging of some products admit "no topical formulation can completely eliminate stretch marks"). Still, some products left testers oohing and aahing at their results. Find out which products and ingredients made a difference.

Image via @biooilusa

Before we dive into stretch mark creams, here's what you need to know: When you quickly increase in size, you stretch the elastin in your skin (located in the dermis) and that ultimately causes it to break down. "Think of it as pulling a rubber band," says Murad. "If you keep stretching and stretching, it doesn't come back to the same shape."

As for improving their appearance, any marks that have turned white are sadly ones you may need to learn to love. "But if stretch marks are relatively new (usually dark in color), you should see results within three months of daily application," Murad says. If the marks are white and have been around for years, that means the skin has undergone more or less permanent damage. (But remember, it happens to a lot of us.) "[At that point] I'm not sure a cream can do a lot of good, though it's worth a try," says Murad. "It may take five to six months to show results."

Now that you've gotten the lowdown on stretch marks, it's time to dive into testing stretch mark creams. Do they really work? Let's find out.

Claims: "Decreases the appearance of existing stretch marks" with the use of Darutoside (a botanical ingredient shown to help with the texture and size of stretch marks) and Registril (a combo of plant extracts shown to improve stretch marks' depth and color)

Pros: Safe for use during pregnancy and breastfeeding, contains natural and organic ingredients, free of dyes, parabens and phthalates, easy to apply, short drying time

Cons: Expensive, must be used twice daily for first month

Results: "True to this product's word, it is a 'minimizing cream,' not a 'disappearing cream.' I started using the [citrus-scented] cream a week after having my third child, and although I can't say my stretch marks are gone, I can say that their color has faded and my skin [texture] is much smoother." — Robin

Claims: "Highly effective in helping to improve the appearance of existing stretch marks ... helps to increase the elasticity of the skin, thereby helping to reduce the possibility of new stretch marks forming." The product claims to do so using a number of plant oils, including anti-inflammatory Calendula and Chamomile oils.

Pros: Goes on smoothly, non-greasy, no drying time, pleasant fragrance, possibly preventative

Cons: Lack of visible results

Comments: "Overall this product didn't produce any noticeable results for me; my stretch marks appear to be the same as before." — Kristen

Claims: "Minimizes imperfections and reduces the visible appearance of cellulite and stretch marks." The product's active ingredients include cayenne pepper, which supports circulation, and Cat's Claw, a plant extract shown to reduce dimpled skin.

Pros: Smells nice and dries quickly

Cons: Expensive, tingles, must be applied twice daily, recommended for use along with several other Murad products

Comments: "Used with Murad's Firm and Tone Dietary Supplement Pack, $138, I noticed slight differences such as improved skin tone, less noticeable cellulite that must have been smoothed out ... and less redness in new stretch marks. But distinct white stretch marks that formed long ago stuck around along with some cellulite." — Debra