Taken from:
http://www.kidshealth.org/teen/your_...tch_marks.html
Although there are tons of creams and other skin products on the market that claim to eliminate stretch marks, the truth is that most are ineffective and often costly. You can't make stretch marks go away entirely without the help of a dermatologist (a doctor who specializes in treating skin problems) or plastic surgeon. These doctors may use one of many types of treatments -from actual surgery to techniques such as microdermabrasion and laser treatment - that reduce the appearance of stretch marks. These techniques are expensive and are not usually recommended for people in their teen years because they are not finished growing and their stretch marks will probably diminish over time anyway.
Some people find that sunless tanning treatments (both over-the-counter lotions and sprays and in-salon types of treatments) can help cover up stretch marks. This doesn't work for regular tanning or tanning beds, though, because stretch marks themselves are less likely to tan. And as everyone knows, the sun and tanning beds do more harm than good when it comes to the long-term health of your skin. You also can buy body makeup matched to the tone of your skin that can make stretch marks all but invisible. Although some manufacturers make these cover-up products water-resistant, makeup may not be the best solution if you'll be spending a lot of time in the water.