I recently received an email from a reader stating that Paula Begoun says you can use a retinoid with an acidic product, and wanting to know why I disagree.
As longtime FutureDerm fans know, I’ve battled it out with Paula before over alcohol use in skin care (my post, her response). I have the utmost respect for Paula; her company is an inspiration, and her work ethic is superb. But I don’t always agree with her opinions, especially when she cites studies that utilize ingredients (like alcohol) for oral consumption and applies the logic universally to topical products. Physiology matters; if you don’t believe me, consider that alkaline food (or product that leaves an alkaline ash in the system) is better for oral consumption, but alkaline products disrupt the delicate acid mantle of the skin when topically applied (Dermatology). Many more examples exist, but this is just one instance.
That said, I definitely don’t want to battle it out with Paula again. But, to answer the reader’s question, I do stand by my assertion: You cannot use a retinoid with acidic products. You can try with the newer formulations on the market with microencapsulation, liposomes, and other advanced delivery methods that accelerate delivery of each ingredient so they don’t necessarily mix, but I still do not risk it. Here is why:
Retinol is Better at a Neutral pH
There is just one reason why the ultra-potent retinol is not listed as a drug in the U.S., and it’s not because cosmetic companies are paying off the governmental agencies: Rather, retinol must penetrate the skin and then be converted into its active form. Drugs, on the other hand, are already active compounds that do not require activation in the skin.
Certain factors matter when it comes to activating retinol in the skin. One of them is pH. The pH optimal for retinol esterification (activation) is between 5.5-6.0, as mentioned in the Journal of Investigative Dermatology.
Most acidic ingredients used in conjunction with retinol will negate its activity. This effect can be slight, as in formulations that are already made with retinol and acids, which are typically slightly out of the ideal range. On the other hand, this effect can also be significant, as when you use separate retinol and acidic products, which typically have a pH of 2-4 and can penetrate the skin very well, taking the skin out of its ideal retinol esterification range.
There are a few products which claim to contain micronized or encapsulated forms of retinol that can be used in conjunction with acids. These forms of retinol are slowly released within the skin over time. The idea is that acidic ingredients like vitamin C will lose its impact, allowing the skin to return to its natural low-neutral pH, so retinol can act on skin at the proper pH. However, I still feel maximum efficacy occurs when the use of these ingredients is separated. I prefer vitamin C use in the morning, with retinoids at night.
Vitamin C is Better at an Acidic pH
Vitamin C is also not as effective when used in conjunction with retinoids.
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, meaning it has an additional “H+” ion, and more significantly for you, this means it can better penetrate the skin. This protonation and penetration is the reason why your skin “flakes” a little bit when you use acidic products — you are getting the maximal effects from acidic products when you allow for them to naturally desquamate or exfoliate the skin.
Unfortunately, vitamin C (as ascorbic acid) should not be used with retinoids. Again, the pH optimal for retinol esterification (a process necessary for its activation in the skin) is between 5.5-6.0, as mentioned in the Journal of Investigative Dermatology. Why mix an acidic solution with a pH of 2-4 with a neutral retinol solution between 5.5 and 6.0, and end up with a pH something like 4-5 that is not ideal for either ingredient?!
Other Experts Agree with Me
According to dermatologist Dr. Leslie Baumann, M.D. in an exclusive interview with FutureDerm: “You have to also be careful not to use a product that has ingredients that can render the active ingredient useless, Vitamin C (L-Ascorbic Acid), glycolic acid (AHA), and salicylic acid and kojic acid can break down retinols and retinoids.”
Dr. Jeanette Graf, M.D., a dermatologist from NYC, says that her opinion depends on whether it is a new or older formulation: “So much of it depends on the formulation. Retinol converts to its active all-trans retinoic acid form once it has already penetrated the skin, and therefore the pH is more physiologic when the reaction takes place. In today’s formulations with newer delivery systems, which make for more efficient products without the need to irritate the outer layer, I would say they can both be used.” Therefore, according to Dr. Graf, newer formulations with technologies like microencapsulation, liposomal delivery systems, or accelerated delivery methods are likely to be fine in combination with acids, whereas those formulations that are older are not likely to work with acids.
Waiting Helps, but Compliance is an Issue
Some skin care fanatics love to apply a potent vitamin C serum or another acidic product, wait 30-45 minutes, and then apply their retinoid.
This is an OK strategy. On the one hand, your skin will re-metabolize back to its original pH within 30-45 minutes of applying most products in an extreme pH range, unless we are talking about a 40% glycolic acid peel or something like that. But I digress. In most cases, this is a fine strategy that will allow potent concentrations of both ingredients to work in your skin.
But on the other hand, compliance is an issue. Even the biggest skin care fanatic (myself included) has other things in life to take care of. One missed application turns into two, and pretty soon, you’ve gone half a month applying either vitamin C or retinol, and aren’t getting the full effects of either. (It takes about four weeks of daily use to reach “pinnacle” benefits from any product).
I personally think it’s better to apply an acidic antioxidant serum in the daytime, and a retinol serum at night.
- If you must use an acidic product in combination with a retinoid, the order in which you apply each ingredient does not matter. The thinner product should always be applied first, regardless of whether it is an acid or a retinoid.
- If you must use an acidic product in combination with a retinoid, wait at least 30 minutes between the application of each. Note that you still may not get the full effects of either product using this approach.
- A formulation that incorporates both acids and retinoids together into one is more likely to still be efficacious if it includes words such as “microencapsulation,” “liposomes,” or “advanced delivery system,” which indicates the product penetrates the skin rapidly and is not impacted by surrounding ingredients. Newer advanced formulations (post-2010) tend to do this.
- I personally still think it is best to use acidic products, like glycolic acid, vitamin C as L-ascorbic acid, or lactic acid in the morning. Save the retinoids for night.
What are your thoughts? Let me know in comments below!