B7, also known as Biotin and Vitamin H, is a common supplement that triggers acne prone skin because it works by increasing cell proliferation.  This is problematic because someone with acne prone skin is already turning over dead skin cells 4-5 times faster than someone who has healthy skin cells.  When you compound the problem of too much cell turnover then more dead skin cells will build up into your pores, and acne will start to form.  

B7 is in Hair, Skin and Nail supplements, B-Complex, multivitamins, nutritional powders as well as Egg yolks, organic meats, avocados and cauliflower.  

Remember to check your ingredient labels to ensure you are not taking products that contain B7 (Biotin and Vitamin H)