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We're often asked about the claim that AHA and BHA exfoliants "deactivate" or reduce the effectiveness of retinol. We've also read similar cautionary statements in beauty magazines that retinol works better without AHA or BHA exfoliants—or that, gasp, it shouldn't be paired with vitamin C.
If smoother, younger-looking skin is your goal, where do you start given all this misinformation? The confusion ends here—as always, we turn to the research to bring you the myth-busting facts.
False! No research anywhere (we repeat, anywhere) demonstrates or concludes that AHA or BHA exfoliants deactivates or makes retinol any less effective when used in the same skin-care routine.
In fact, whenever we see a comment or recommendation about not using retinol with AHA or BHA exfoliants, the advisement is never supported by research demonstrating that incompatibility. It's one of those falsehoods that gets repeated so often, people (even dermatologists) tend to believe it rather than question it.
It turns out that the claim of retinol not working with AHA or BHA exfoliants involves a misunderstanding about how skin-care ingredients work together, and how each affects the structure of the skin. Let's dig a little deeper and find out just how wrong this claim is in our next myth…
The confusion about using retinol with AHA or BHA products has to do with concern over the exfoliants' acidity lowering the skin's pH, thus (as the claim goes) disrupting the retinol's ability to work its anti-aging, skin-smoothing magic.
The reasoning behind this claim is that if the pH of the skin is below 5.5 to 6, an enzyme in your skin won't be able to convert the retinol into retinoic acid (a form of vitamin A), which is the active form of retinol. This is all based on the assumption that the acidic exfoliant ingredients lower the pH of the skin, but that's not what happens.
Just like most skin-care rumors, this one sprang from a misunderstanding about the research.
Only one study (from 1990) mentions the pH range and skin enzyme issue described above. However, that study was performed on a blend of animal and human proteins, and the pH relationship issue developed only when a fatty acid by-product was added to the mix (in other words, not on normal human proteins and not on healthy, intact skin).
To further emphasize how misguided the assumption of retinol's incompatibility with AHA or BHA is, the study in question clearly states, "no clear optimal [pH range] was seen when the assay was run without [fatty acid byproduct]."
In the end, this single study was used only to compare how animal and human skin metabolizes the form of vitamin A naturally present in skin, not about how topical vitamin A benefits (or functions in) skin. Its conclusions were not intended to be used to make decisions about skin care.
Topically applied vitamin A does not replace or substitute the body's development or the function of retinoic acid. It's like thinking you could apply vitamin C into your eyes to prevent macular degeneration rather than eating vitamin C-rich foods.
Fun fact: Retinol occurs as a solid that must be dissolved in a carrier oil, which makes it a waterless ingredient. Its waterless composition means that there is no pH to consider, even when it is layered with acidic ingredients—you cannot establish a pH in a waterless product!
It's worth noting that no research has replicated the pH limitations of the 1990 study. Yet despite the lack of follow-up supporting research, that study is still cited (solely) to support the inaccurate claim that retinol cannot be used with AHA, BHA, or, as you'll see in myth #6, with vitamin C.
You may be surprised to find out that research has shown that retinol combined with exfoliants like AHAs helps fade hyperpigmentation in skin, and improves the results you get from both ingredients on the skin. We often wonder how those who argue against combining retinol with AHA or BHA exfoliants overlook that information.
The belief that skin's pH neutralizes acidic skin-care products applied to its surface is misguided. A neutral pH is 7, yet skin is naturally acidic, more so than thought in the one, lone study that's often cited. Today's research demonstrates that skin's pH actually hovers between 4.7 and 5. Does this then mean you must raise your skin's pH to use a retinol product? Of course not! We know from research that retinol works when applied to the skin, and it works at the skin's naturally acidic pH.
Retinol and exfoliants work very differently to improve skin, but complement each other when paired in a complete skin-care routine. It's a popular misconception that the way retinol works is by exfoliating skin, so we understand why this issue has become confusing. Here are the facts:
Retinol does not cause the same sensitivity to daylight as tretinoin, it's more potent, prescription-only form (brand name examples are Renova or Retin-A). Research has shown that retinol and vitamin C work well under SPF-rated products to protect the skin from UV light, and that vitamins A, C, and E, even when in combination, also remain stable and effective under an SPF-rated product.
Research also has shown that a vitamin A and E combination remains stable under UV exposure plus sunscreen, as does pure vitamin A used alone. That's excellent proof of retinol's stability when paired with a sunscreen.
Antioxidants plus sunscreen are a formidable defense against wrinkles, uneven skin tone, loss of firmness, and brown spots. For best results, be sure to apply antioxidant-rich skin-care products morning and evening.
Vitamin C (ascorbic acid and its derivatives) is another ingredient often cited as a problem when combined with retinol. As with the AHA and BHA myth, this one is also based on the pH/acidity issue.
The truth: Vitamin C (depending on the form) requires a low pH (or no pH at all, as is the case in non-aqueous, silicone-based formulas) to remain stable. We know retinol works in an acidic environment and that skin's pH is naturally acidic, so from what the research has shown us, here's a clear case where the coupling of vitamin C + retinol makes sense.
Research has shown that a combination of vitamins in cosmetics is the way to achieve the best results, including the combination of vitamins A, C, and E. In a double-whammy myth-buster, retinol proved to be not only effective when paired with vitamin C, but the two also worked beautifully to defend skin against free radicals when applied under a sunscreen! That wouldn't be the case if retinol made vitamin C ineffective or vice-versa.
Vitamin C actually helps retinol work better! It fights free radicals, a process that helps protect retinol from oxidization as it penetrates deeper into the skin—thereby increasing its anti-aging benefits! One could argue that not using retinol with vitamin C (or some other potent antioxidant) puts your skin at a disadvantage.
We've presented the research-based facts above, but, ultimately, it's your choice as to what is best for your skin. What you don't need is "junk science" or persistent myths taken as facts.
There is no research anywhere that supports the misguided assertion that retinol is deactivated when combined with acidic ingredients, and there is plenty of research that demonstrates the opposite. In fact, cosmetics chemists who specialize in developing retinol formulas balk at this, and we've asked around—a lot!
The Best Skin of Your Life Starts Here: The same type of in-depth scientific research used to create this article is also used to formulate Paula’s Choice Skincare products. You’ll find products for all skin types and a range of concerns, from acne and sensitive skin to wrinkles, pores, and sun damage. With Paula’s Choice Skincare, you can get (and keep) the best skin of your life! See Paula's Choice Retinol Treatments.
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Paula Begoun is the best-selling author of 20 books on skin care and makeup. She is known worldwide as the Cosmetics Cop and creator of Paula's Choice. Paula's expertise has led to hundreds of appearances on national and international television including:
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The Paula's Choice Research Team is dedicated to busting beauty myths and helping you solve your skincare frustrations with research-supported expert advice—so you'll have the facts you need to take the best possible care of your skin.
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