Stretch marks happen. They just do. Growth spurts, pregnancies, dramatic weight gain, even the use of some drugs (i.e. corticosteroids) can cause or exacerbate the appearance of stretch marks. They're just a part of life. But they don't have to be a very visible part of life. You can actually diminish the appearance of stretch marks.
Stretch marks are long, narrow streaks that may be red or purple (over time they may fade to a silvery sheen). These streaks are the result of skin stretching over weak connective tissue (because elastin fibers have been broken). Medically, stretch marks present no concern. Cosmetically, it's a whole different story.
There really is no magic formula, lotion or serum that can completely remove stretch marks. However, there are some skincare products and procedures that can significantly reduce their visibility. More intensive therapies include:
Tretinoin is a retinoid, a compound that encourages cell turnover and growth. Topical application can quicken the facing process of new stretch marks. However, it is not recommended for pregnant women.