Stretch marks, or striae, are unsightly marks or scars that can occur on nearly all parts of the skin. They look like red, purple, or pink stripes, or they can appear as line-like areas of lighter or darker than normal skin. They often occur after a rapid growth spurt or weight gain and therefore, are most commonly found where growth and excess fat occur on the thighs, abdomen, breasts, or upper arms. While not harmful, they can cause a significant amount of psychological distress for patients.