Dr. Doireann O’Leary on Instagram: "Tretinoin is the gold standard for anti-aging skin care. It stimulates collagen and elastin, as well as increasing skin cell turnover. Over time, it gives skin a firmer appearance with reduced fine lines and wrinkles. It’s also a great treatment for acne, pigmentation and melasma. It can be used to treat keratosis pilaris, often referred to as “chicken skin”, often seen at the back of the arm. It can be useful for molluscum contagiosum, the wart-like lesion th