Q: Is it more effective to use products from only one skincare line rather than mix different brands?
A: If you're like lots of us, you probably use products that contain active ingredients (alpha hydroxy acids to treat aging skin, for example). Typically the ingredients and products in a skincare line are formulated to work synergistically to maximize results and minimize side effects, says Jennifer Linder, MD, clinical instructor of dermatology at the University of California, San Francisco. Many of her patients make the mistake of mixing the strongest products of several lines, which irritates their skin. It's especially important to be careful with retinoids, alpha hydroxy acids, hydroquinone, and salicylic acid, because the skin can become overstimulated if these ingredients are used simultaneously.
Bottom line: If you use only a gentle nonsoap cleanser, moisturizer, and sunscreen, you can mix brands with abandon. But if you're trying to target specific skin conditions, it's better to stick with only one line.