Getty Some things are just meant to be together. We could list some, but let your imagination wander. Other things are better suited on their own—especially when it comes to certain skincare products. Powerful ingredients such as retinol, Vitamin C, benzoyl peroxide, and even certain acids demand to be the star of the show. Sharing the stage could lead to major drama in the form of irritation, redness, temporary staining, or just a general lack of desired results. "There are so many great active ingredients out there and it may seem like using more of them would give you better results, but that’s not always the case," says Aegean Chan, a board-certified dermatologist based in Santa Barbara, California.