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In This Article:
The claim of AHA and BHA exfoliants "deactivating" or reducing the effectiveness of retinol is one we're asked about often. As always, we turn to the research to see what it states and then bring you the facts, so you can make the best decision for your skin.
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.
Here's what you need to know: No research anywhere (we repeat, anywhere) demonstrates or concludes that AHA or BHA exfoliants deactivate retinol in cosmetics. Any information to the contrary is a result of personal assumptions by writers whose conclusions are not supported by evidence. Whenever we see a comment or recommendation about not using retinol with AHA or BHA exfoliants, the advisement is never supported by any research demonstrating that incompatibility because there is no research to show that this is, in fact, true.
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 disrupting the retinol's ability to work its anti-aging magic. The fear 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, which is the active form of the ingredient, and what is present in prescription retinol products such as Retin-A. 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. The study 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 retinol. It was not intended to show how topically applied retinol products actually work, nor were its conclusions intended to be used to make decisions about skin care—yet that's exactly the misinformation that's been flying around online and in some fashion magazines.
To give you an idea of how early, and now outdated, this study was, the researchers identified only one method of how skin uses retinol—we now know there are multiple avenues in which the skin can convert retinol to retinoic acid. Only a few years after the 1990 study, scientists had identified another, more dominant, skin enzyme involved in the conversion of retinol (1996 study of retinoic acid conversion). Since then, 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 assertion that retinol cannot be used with AHA, BHA, or 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 also improves the results you get from both ingredients on the skin. We often wonder how that information gets overlooked by those who argue against combining retinol with AHA or BHA exfoliants.
More to consider:
Another example to illustrate our point: Muscles convert glucose (sugar) to lactic acid during exercise. So, should we use only lactic acid–based AHA exfoliants during exercise? Of course not, but you get our point.
The belief that skin's pH neutralizes acidic skin-care products applied to its surface is misguided. 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.
Vitamin C (ascorbic acid and its derivatives) is another ingredient often cited as a problem when combined with retinol, again based on the pH/acidity issue. This is further confusion of skin-care science. 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 makes sense.
Research has demonstrated 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 simply 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 the retinol's anti-aging benefits! One could argue that not using retinol with vitamin C (or some other potent antioxidant) puts your skin at a disadvantage.
Retinol does not cause the same sensitivity to daylight as tretinoin, it's more potent, prescription-only form (brand name examples: Renova or Retin-A). Research has shown that retinol and vitamin C work well under SPF-rated products to protect the skin from exposure to UVA/UVB radiation, 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.
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" when it comes to making decisions about skin-care products and your personal skin-care routine.
In summary: 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 Paula's Choice Research Team will always provide you with reliable information so you can take the best possible care of your skin.
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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 TV including:
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The Paula's Choice Research Team is dedicated to helping you find the absolute best products for your skin using research-based criteria to review beauty products from an honest, balanced perspective.
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