For the same reason you shouldn't be waxing skin that has recently been treated with retinol, you also shouldn't be getting a professional chemical peel while using retinol. While both are great for decreasing the appearance of wrinkles (and retinol has even been shown to be a great weapon in the battle against acne), Dr. Graf says that the combination of the two can cause too much irritation.

Using retinol or Retin-A (the stronger, prescription form of retinol) makes the skin barrier more penetrable, which means the ingredients in a professional-grade chemical peel will get deep into your skin, fast. While you might think that sounds like a good idea, it's actually a recipe for burning and irritation, along with physical reactions like redness, peeling, crusting, swelling and blistering. A too-deep peel can even increase your chances of getting a post-peel infection, especially if you can't resist applying makeup to cover up that persistent redness. Dr. Graf says that the process of preparing for a peel varies by patient and the type and strength of the chemicals used, so talk to your dermatologist a few weeks before the peel to get an idea of the proper pre-op procedure for your skin.

Most of us have a skin care routine we stick to. Cleanse, tone, treat, and moisturize is a regimen that almost everyone is familiar with. But Dr. Graf says that if you're using a retinol, you can skip one of those steps. Traditionally, toners are used to rebalance the skin after cleansing, but Dr. Graf says that that practice is outdated, since cleansers on the market today are pH balanced. "Toners are from the days when cleansers were not pH balanced," she says."

The benefit that people get from using toners these days are from added ingredients, like salicylic acid for acne, or chamomile for anti-inflammation. Depending on the toner formulation, it can be irritating (if it's meant to treat acne), or just plain unnecessary (if it's meant to exfoliate) when used in combination with retinol. "If you're using retinol, you don't need the addition of toner," says Dr. Graf, who adds that besides being unnecessary, using toner in conjunction with retinol can be irritating if it's formulated with harsh ingredients like alcohol. Retinol evens skin tone and treats hyperpigmentation (the darkening of skin) and acne, which are the same benefits we're hoping to get from daily toner use. Moral of the story? While your face isn't going to burst into flames if you combine these two skin care products, it's not going to be beneficial, either. At best, it does nothing. So, save your money and skip the toner.