When introducing a new active ingredient into your skin care routine, you may wonder how well it will mix with the others you already use—or, worst case scenario, if using both of them together will lead to irritation. Unfortunately, much of the information circulating about active ingredients is confusing, and even downright incorrect, which leaves all of us with more questions than answers. For example, some sites will tell you that using retinol and vitamin C together is a recipe for disaster, while other claim that this combination can be beneficial. Similarly, some articles claim that niacinamide and vitamin C should be avoided, while others state that using this duo in tandem actually purports some serious benefits.

So, what is the truth? When it comes down to it, nearly all active ingredients can be used together—as long as they are used correctly, applied at the right times and the right strengths. Here, we’re sharing science-backed ways to properly combine potent topical ingredients without causing any irritation or redness along the way.


Perhaps the most commonly professed skincare “don’t” is using retinol together with vitamin C—however, that is not to say you can’t use both ingredients on a daily basis. Because both ingredients work most effectively at different pH levels (retinol at around 5.5, and L-ascorbic acid at 3.5), the ideal way to utilize both ingredients is by using vitamin C in the morning and retinol at night. In addition to preventing potential irritation, this method also lends itself to the benefits of both ingredients; Vitamin C provides antioxidant protection from environmental aggressors (like UV rays and air pollution) during the day, while retinol helps boost your natural skin cell renewal cycle overnight. If you have sensitive skin, start out by applying your retinol serum every other night, or every third night, and gradually work your way up to everyday use.

When it comes down to it, nearly all active ingredients can be used together—as long as they are used correctly, applied at the right times and the right strengths.



Despite popular belief, research shows that using niacinamide and vitamin C (L-ascorbic acid) together does not neutralize the effectiveness of one or the other, nor does it lead to any skin irritation. On the contrary, using these two ingredients together—even layering one on top of the other—can lead to a host of skin benefits. Research has demonstrated the anti-aging capabilities of niacinamide, as well as the potent antioxidant properties of vitamin C. So, combining the two together is basically a one-two punch for preventing and staving off signs of skin aging.

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These two ingredients not only go well together, but niacinamide can actually help prevent some of the potential irritation that’s commonly associated with retinol. For this reason, you’ll often find the two actives formulated into the same product, although layering niacinamide on top of your retinol serum will achieve the same beneficial results. One of the mechanisms by which niacinamide helps to curb potential inflammation is by boosting ceramide levels in the skin, in turn strengthening the skin barrier and making it more resilient against potential irritants.



While it’s true that both of these ingredients are technically acids, and that applying too much acid onto your skin at one time can do more harm than good, this does not mean that both ingredients can’t be used together. Similar to vitamin C, in order to use both chemical exfoliants on a daily basis, apply each ingredient at a different time of day; Typically, AHAs and BHAs in the morning, and retinol in the evening. That said, people with oily skin or a naturally strong skin barrier may be able to use both ingredients together, one after the other. To figure out if this is you, or to build your skin’s tolerance levels up, applying retinol after using either AHAs or BHAs in the evening—start by using retinol every other day, then work your way up to daily application.

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