"My favourite drugstore retinol is Differin Adapalene Gel 0.1% ($15). It not only works wonders for acne, but for anti-ageing, too. Retinol, a derivative of vitamin A, encourages cell turnover and has been scientifically proven to stimulate collagen and elastin, improve the appearance of wrinkles, and diminish brown spots. Be careful not to use too often when you first include it in your skin-care routine. Use it one to two times a week at night and slowly use more frequently over a couple of weeks. If you use too much too soon, you can dry and irritate your skin, making acne worse." — Sarah Akram, celebrity aesthetician