By Beth Janes
Essentially scars within your skin, stretch marks occur when you gain weight quickly (puberty and pregnancy are causes), which tears collagen. The resulting inflammation creates red or purple streaks that eventually turn white. To make matters worse, sometimes overstretched skin gets thinner, so the marks are even more noticeable.
Prescription tretinoin: One study found that it may help improve the appearance of newer stretch marks. It also amps up collagen production and thickens the top layer of your skin, diminishing marks, says John Canady, MD, president of the American Society of Plastic Surgeons. The drawbacks? Tretinoin may cause side effects such as redness and flaking and it may be risky for nursing moms.