3 Surprising Combinations of Ingredients You Might Not Want in Your Skin Care

Skin Care

Like having the appetizer and the dessert, or maxxing out your credit card with the Chanel and the Fendi, sometimes you really can have too much of a good thing.   And while you may not think it, there are some combinations of beneficial skin care ingredients that lose effectiveness when they are used in conjunction together.  Here are some of the surprising combinations of ingredients you may wish to avoid:

1.  Niacinamide and Sirtuins

In this 2005 study conducted at Johns Hopkins University, it was found that free nicotinamide (i.e., niacinamide) inhibits sirtuin activity in a mechanism mediated by niacinamide binding in a conserved pocket that participates in NAD(+) binding and catalysis.  In plain English, this means that your attempts to prolong the life of your collagen-producing fibroblasts by turning off unnecessary gene expression with sirtuins will most likely be negated by niacinamide.  Which makes sense, really: when your body wants to turn off the action of sirtuins, it naturally produces additional quantities of related compound nicotinamide adenine dinucleotide (NAD).

So what are you to do if you want both the skin-friendly benefits of niacinamide (reduction in hyperpigmentation, red spots, sallowness, and the appearance of fine lines and wrinkles) and sirtuins (proposed prolonged collagen production)?  Two options come to mind:  One,  use the ingredients in alternating skin care regimens.  By using sirtuins without niacinamide periodically for weeks at a time, the theorized turnoff of fibroblast gene expression could take place.   However, it is unknown what would occur when you stop using products containing sirtuins and the fibroblasts are turned back on.  It is possible that it is more stressful to turn fibroblast gene expression on and off, but then again, it is also possible that fibroblast life is like a bank: take a little out here, stop for a while without penalty, take a little more out until there is no life left.  At this point, it is hard to say, and I cannot find research to support either theory.  (Please let me know if you are aware of such information!)

The other option is to use products with niacinamide and preserving your skin’s collagen production levels with other proven methods, which include UV ray avoidance, use of retinoids and antioxidants, and stimulation via certain dermatological treatments (CO2 laser, microdermabrasion, and even Botox, according to some reports).  As always, talk to your dermatologist to customize your optimal skin care regimen.

2.  Retinoids and AHAs/BHAs

According to Dr. Leslie Baumann, M.D., Chief of the Department of Cosmetic Dermatology and Professor of 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.  Instead, Dr. Baumann recommends using BHAs in the morning under sunscreen and retinoids or AHAs at night, as BHAs may thin the skin and sensitize the sun, but this has not yet been proven, whereas retinoids and AHAs have been proven to sensitize the skin to the sun.

So why should retinoids and AHAs and BHAs not be used together?  One answer is that the optimal pH environment for each ingredient differs.  For instance, in Dr. Baumann’s Cosmetic Dermatology textbook, it is noted that the optimal pKa of AHAs is approximately 3.83, whereas for BHAs it is 2.97.  (When the pH is greater than the pKa, the inactive “salt” form of these acidic ingredients predominates).  Given that the the pH optimal for retinol esterification (which may be thought of simply as activation) is reported in the Journal of Investigative Dermatology to be between 5.5-6.0,  it would be virtually impossible to achieve a pH in which the activity of all three ingredients would be optimized (i.e., pH < pKa for AHAs/BHAs) and in which all the ingredients are included in effective concentrations within the same solution, or when applied to the skin synchronously.

Another reason why you may not wish to use AHAs, BHAs, and retinoids together is because all may work, at least in part, by thinning the stratum corneum (the outermost layer of skin).  While it has been proven in Dermatologic Surgery (amongst others) that the overall thickness of the skin is increased with AHA use, it has also been established that both AHAs and retinoids thin the stratum corneum.   Furthermore, while it has been well-documented that retinoids increase photosensitivity, some studies show that AHAs increase photosensitivity and other studies show that AHAs actually have a photoprotective effect (according to the textbook Cosmetic Dermatology by Dr. Murad Alam et. al.).  With that said, until the verdict is officially out, I think I personally will avoid using AHAs and retinoids together, and I will certainly restrict retinoid use to nighttime.  As for what is best for you – I’ve said it once, I’ll say it again – always talk to your dermatologist. 🙂

3.  Vitamin A and Vitamin C (mostly as L-Ascorbic acid)

Now, before I start this, I just want to affirm that there are many, many great formulations with vitamin A (i.e., retinoids, retinol, retinyl palmitate, etc.) and C that are out there.  However, to achieve the full-fledged benefits of each ingredient, you may just want to apply them separately (i.e., products containing vitamin C in the morning, products containing vitamin A in the evening).  The reason?  Again, a matter of optimal pH:  it has been reported in the Journal of Dermatological Surgery that vitamin C and its derivatives should be formulated at a pH under 3.5 in order to allow the vitamin C to enter the skin (at this pH level, the molecule is protonated and thus can penetrate the skin).  Unfortunately, the pH optimal for retinol esterification, as mentioned before from the Journal of Investigative Dermatology, is between 5.5-6.0.   This doesn’t mean that products containing vitamin A and C don’t work – many products I love contain both! – but it does indicate that using them separately may be a bit more beneficial.  (For even more benefit, I like using vitamin C, which is a proven network antioxidant, instead in conjunction with other network antioxidants [vitamin E, coenzyme Q10, glutathione, lipoic acid] for increased antioxidant power).

One further note:  the form of vitamin A and vitamin C does matter when it comes to pH considerations.  Although vitamin C as L-ascorbic acid has the highest natural antioxidant concentration in the skin and the most researched benefits to date, other less acidic (higher pH) forms do exist.  According to a 1997 study in the Journal of Pharmaceutical and Biomedical Analysis, magnesium ascorbyl palmitate has greater stability than both L-ascorbic acid and ascorbyl palmitate.  Magnesium ascorbyl palmitate also has an optimal pH of 7.0-8.5.  Therefore, it is definitely possible to make a formulation with a beneficial pH environment using vitamin A (optimal pH 5.5-6.0) and quite a small amount of vitamin C derivatives like magnesium ascorbyl palmitate.  However, given that it is unclear what effect combining L-ascorbic acid with moisturizing vehicles may have on its action and what concentrations of many vitamin C derivatives are required for full benefits, I may stick to my separate use of vitamin A and vitamin C, at least for the most part.  🙂

Overall Thoughts

While using niacinamide + sirtuins, vitamin A + AHAs, or vitamin A + vitamin C together is very unlikely to be harmful, it seems that using certain ingredients separately may get you the most benefit, or the biggest bang for your buck, if you will.  With that said, I personally love vitamin C and other antioxidants, niacinamide or nicotinic acid, and sunscreen galore in the morning, while I save retinoids and peptides and non-vitamin C antioxidants for night.  As always, you can find a dermatologist to help optimize skin care for you through the American Academy of Dermatology website here.


Photo source: Droster Lock (Infinite Combination) Originally uploaded by fpsurgeon (flickr)

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  • Obadina Ayodeji M

    What if i use Neutrogena pore refining Aha&Bha cleanser with Neutrogena healthy skin antiwrinkle retinol spf 15 cream.

  • Di

    I am wondering if I can mix L-ascorbic acid and arbutin, kojic acid, nicinamide and other skin lightening actives. Would they increase each others effects or some how cancel the effect?

  • Ruben

    PS: My finalproject is entiteled ‘Cosmetic actives – Technical, customer and markting research’ When finished I’ll send you a copy 🙂

  • Ruben

    I’m studying cosmetic science and my professor said that when we make an emulsion containing AHA/BHA/Retinol or any other ingredient which require a higher pH then the AHA/BHA we can simply fix that by creating an O/W/O/W emulsion, better known as a MLE (Multipule Layer Emulsion). We then do the AHA/BHA in one O/W emulsion with the correct pH and add another O/W emulsion with the retinol to it! This way you can easily combine them both without harming the pH effectiness.

    Also many cosmetic products containing VIT A are just in it to help the Oils from oxidation during the heating up process. example: we make an Night Cream O/W or W/O and insert retinyl palmitate to the oil phase to protect the oil when it’s being warmed up till 70° or so. It has no real benefits for the skin just to help prevent the oil from Oxidation, it’s usually then in products with an 0,5% concentration, ofcourse this doesn’t go for retinol since that’s active that you add in the Temperature sensitive fase. Same goes for Tocopherol oil which is just inserted to protect the oil, it’s Tocopherol acetate that has benefits for the skin.

  • Susan

    Can you apply a moisture cream after a Vit A cream to help minimize irritation and dryness? If so, how much after should you apply.

    Thank you

  • joseph

    FANTASTIC article! i’ve been a skincare junky for the past decade and the past few years i’ve really become interested in the formulation process. this article shows me some of the things cosmetic chemists have to take into consideration to create quality, effective formulations!! thank you so much!

  • Rose

    Hi, thanks for the information! I was wondering, if I use a cleanser with salicylic acid before using retinol, will that have adverse effects? Also, does AHA/BHA working best at different pH levels than retinoids mean that any of the products actually change the pH level? If not, how would using the products together make the situation worse (i.e., make the pH less favorable to one of the products) than it already is?

  • hayley

    The MD skincare peel is said to contain retin-a and aha’s and bha’s. What do you make of this?
    I think it has thinned my skin a little, but I expect that if I lay off it for a while, my skin will regenerate.

  • Lauren

    Great information! You mentioned there’s evidence that BHA’s thin the skin. Is that a permanent effect that can ultimately lead to more aging? I’ve been using an antioxidant face lotion with salicylic acid. Now I’m wondering if I’m doing more harm than good.

  • priya

    thankyou so much for the great information.
    how do i know if there is a sirtuin among the ingredients, will it be under the same name among the ingredients? or will it be known under any other names? thanx

  • Dear Nadia,

    I honestly wondered the same thing, because sirtuins supposedly downregulate gene expression of fibroblasts, which, if it is indeed a desired effect, is something you would then want for longer than 12 hours.

    I’ve asked a few derms and none seemed to be sure as of yet…Perhaps research in the future will elucidate this? I’ll let you know =)


  • Nadia Shams

    what if I use Nicinamide in the morning and prosirtuin in the evening? Is that going to work. Cause a product works just a few hours on your skin right?

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