I am a repeat customer of this product. I've been using it for a few years with excellent results on my oily, acne prone skin. I also no longer have any dark, sun damage discoloration. The damage disappeared after using for about six months. Recently, I purchased a different brand of glycolic and didn't care for it at all. Purchased another bottle of this and my skin is much happier. Yes, it burns a little but the results are worth it.