I just read this article titled “skin-care-combinations-that-dont-play-well-together”
- VITAMIN C AND ALPHA-HYDROXY ACIDS (AHAS)
- VITAMIN C AND COPPER PEPTIDES
- RETINOL AND BENZOYL PEROXIDE
- RETINOL AND AHAS
See the article to find out why. Do you know of some other ingredients that should not be mixed, or are there combinations you avoid?