Like steak and Cabernet or Romeo and Juliet, some pairs were just meant to go together. On the other hand, some pairings are nothing short of disastrous. Think white shirts and red wine or orange juice and toothpaste—they’re just plain wrong.
In skin care, there are real advantages to buying products from different skin care lines. Addressing multiple concerns and purchasing the most concentrated products from each line are just two of the reasons why a customer may want to mix and match. Unfortunately, this can create some ingredient pairings that should never, ever be. Here are five of the most common mistakes.
Resorcinol and hydroquinone are both used to treat hyperpigmentation. Although hydroquinone has been ubiquitous in the U.S. skincare market for several decades, resorcinol only recently made it to the shelves in skin-brightening products from Clarins and Philosophy, among others.
Unfortunately, when used in conjunction with hydroquinone, resorcinol has been shown to cause a rare permanent darkening of the skin in patients with darker skin types (especially South Africans). The effect typically appears after six months of continual resorcinol use.
Why does this occur? Resorcinol and hydroquinone both inhibit two enzymes within the skin, tyrosinase and homogentistic acid oxidase. When homogentistic acid oxidase is inhibited, pigment accumulates in the skin. Although the condition is extremely rare in patients who do not have dark skin, I absolutely would not recommend that anyone mix resorcinol and hydroquinone.
2. Niacinamide + Sirtuins
Niacinamide (a form of vitamin B3) softens and hydrates skin, reduces fine lines and wrinkles, and prevents and treat age spots. It’s found in an array of skin care products, such as Olay’s anti-aging line.
Although sirtuins are found in products from Avon and other specialty companies, they are less common. Sirtuins conserve energy within your skin cells by turning off unnecessary gene expression.
Unfortunately, a 2005 study conducted at Johns Hopkins University found that niacinamide inhibits sirtuin activity. The more complicated explanation is outside the scope of this article, but know this: Niacinamide wants to increase cell metabolism, while sirtuins want to decrease it. It’s best just to separate these two ingredients entirely.
3. Retinoids + AHAs/BHAs
According to Dr. Leslie Baumann, Chief of the Department of Cosmetic Dermatology at the University of Miami, retinoids should not be mixed with BHA (salicylic acid) or AHA (glycolic acid) because the BHA and AHAs can inactivate the retinoid.
Why should retinoids and AHAs and BHAs not be used together? The answer is simple: pH. The optimal skin pH level for AHAs is approximately 3.8, whereas for BHAs it is 2.9. For retinoids, it is substantially higher, 5.5-6.0. This means it would be virtually impossible to achieve a pH that would allow all three ingredients to work well at once.
4. Retinoids + Vitamin C
While there are many great formulations with vitamins A and C, you will never get the maximal benefit from vitamin A and vitamin C when you use them together. Again, this is because of pH: it has been reported in the Journal of Dermatological Surgery that vitamin C and its derivatives should be formulated with a pH under 3.5 in order to allow the vitamin C to enter the skin. Unfortunately, the pH optimal for retinol activity, as mentioned before, is higher (5.5-6.0). This doesn’t mean that products containing both vitamin A and C don’t work somewhat—many products I love contain both—but it does suggest that using them separately may be a bit more beneficial.
5. Exfoliants + Glycolic Acid or Retinoids
Glycolic acid is the most common of all the alpha hydroxy acids. Both glycolic acid and retinoids work by increasing cell turnover and thinning the stratum corneum (the uppermost layer of the skin). By exfoliating that top layer of the skin, glycolic acid and retinoids smooth the skin, decrease fine lines and wrinkles, and increase skin firmness by enhancing collagen production.
Unfortunately, because glycolic acid and retinoids thin the skin, using them in conjunction with an exfoliant invites redness, sun sensitivity, and irritation. Do your skin a favor and choose one product or the other in any given night.
So what are you to do if you want to combine skin care products with the above ingredient pairs? A few options exist:
▪ Use the ingredients in alternating skin care regimens. For instance, you could use resorcinol for four months, and then use hydroquinone for four months.
▪ Use the ingredients at alternate times of the day, such as niacinamide during the day and sirtuins at night.
▪ Consider alternatives. Other antioxidants, fractional CO2 lasers, fillers, and even Botox have been shown to have amazing effects on skin’s collagen production without jeopardizing the performance of any of your skin care ingredients.
As always, talk to your dermatologist to best customize your personal skin care regimen.
Read more from Nicki at her blog, Future Derm, or to ask her a question about your own skincare issue, visit her Facebook page.