Glycolic acid face wash work wonders for reducing acne smoothing out the skin and removing dark marks. Don't let the word acid in its name scare you away. It is a fruit acid derived from sugar cane. Glycolic acid is an alpha hydroxyl acid (aha) that increases skin cell turnover therefore removing dead skin cells from the surface of the skin faster. This way it keeps the pores of the skin unclogged and prevents acne. It o lightens brown marks through exfoliation.