I love the glycolic c serum. I have very oily skin, some acne scarring and at 42 some wrinkles. the glycolic c serum reduces the oil at night when I use it, which is every night. I also use the glycolic 40 once a week for about 5 minutes. It is the best glycolic peel I have ever used. It doesn't leave my skin red as some others did. Thank you for making such good products. - Susan E.