There are a lot of rules and best practices to follow when it comes to skincare. One subject that can be particularly tricky is exfoliation. Aside from the obvious questions, like how often you should exfoliate and the difference between chemical and physical exfoliation, another popular question skincare experts hear is: Is it safe to use a chemical exfoliator like an alpha-hydroxy-acid (AHA) or beta-hydroxy-acid (BHA) if you’re already using a retinol? We consulted with Dr. Ted Lain, a board-certified dermatologist based in Austin, Texas, to get answers. What Do AHAs, BHAs and Retinol Do?Retinol is a vitamin A derivative commonly found in anti-aging skincare products. It can help soften the appearance of fine lines and wrinkles, make pores appear smaller and even target acne. “Retinol also helps to increase cell turnover, therefore improving the appearance of brown spots and skin’s brightness,” says Dr. Lain. Like retinol, AHAs, or alpha-hydroxy-acids, can exfoliate the skin by helping increase cell turnover.  Examples of AHAs include glycolic acid, lactic acid, citric acid and malic acid. They are typically derived from milks and fruits, are water-soluble and help promote a smoother, more radiant complexion.  The most common form of BHAs, or beta-hydroxy-acids, is salicylic acid. It’s oil-soluble and because it can exfoliate deep in the pores, it’s great for helping to treat and prevent acne. Is It Safe to Use an AHA or BHA if You’re Using Retinol?“If your skin has already adjusted to the retinol — whether prescription or over-the-counter — meaning no visible signs of redness or scaling, then yes, it is safe to use a mild exfoliator,” says Dr. Lain. “I would recommend starting with a cleanser containing either lipo-hydroxy acid (LHA) or lactic acid (an AHA) because these are the more gentle chemical exfoliating ingredients.” We like the SkinCeuticals LHA Cleansing Gel, which is ideal for oily, combination and acne-prone skin.  Like all forms of exfoliation, the major risk of using a chemical exfoliator and a retinol is irritation in the form of inflammation, redness and flaking. “This can lead to itching and tenderness,” says Dr. Lain.  As such, it’s best to allow your skin time to adjust to your new routine slowly. It’s also important to identify your skin type before attempting to mix a chemical exfoliator and retinol. “Usually the more sensitive skin types should use one or the other and not try to combine them,” he says. “In addition, those with dry skin will likely not tolerate the two products together.”  If you’re new to retinol, you should allow your skin to pass the “adjustment period” before trying to incorporate any additional exfoliating products. You should also start with a low dose of the ingredient. The Kiehl’s Micro-Dose Anti-Aging Retinol Serum and the Garnier Green Labs Retinol-Berry Super Smoothing Night Serum Cream are both great options for retinol beginners.  “I advise starting with retinol applied at night with a moisturizer and gentle cleanser, and using the same cleanser and a broad-spectrum sunscreen in the morning,” says Dr. Lain. “If after four to six weeks of use the skin is healthy with no signs of redness or scaling, then you can start to use a gentle chemical exfoliator in the morning, followed by broad-spectrum sunscreen.”  In need of a chemical exfoliant? Try the L'Oréal Paris Revitalift Derm Intensives 10% Pure Glycolic Acid Serum, which works to even skin tone and reduce the appearance of wrinkles.   Design: Juliana Campisi