Stretch marks, also called striae, are found in rapidly growing preteens and pregnancy when the skin stretches and leaves reddish scars which eventually turn white or flesh colored.  There is no conventional treatment for stretch marks but there is a homeopathic medicine which is effective.  In addition, oral vitamin C 3000 mg a day should be taken to help strengthen the collagen in the skin as it’s growing.  Treatment after the reddish phase is generally not effective, so early treatment is important.