Lindygirl asks… *Sigh* I just found this on my fb feed and now I am confused. Is Paula correct here? You can mix OTC retinols and AHA or BHA? It is a moot point for me now that I am using a low dose prescription retin-A, but I don’t want to be giving other forum members wrong info. Would you guys mind taking a look?
The Right Brain responds:
Lindy, I checked with fellow beauty science blogger and dermatologist, Nicki Zevola from FutureDerm, for an expert opinion. The short answer is that Glycolic acid (an AHA), salicylic acid (a BHA) and even Vitamin C can reduce the efficacy of retinoids. That’s because in order for retinoids to work they must be oxidized to all-trans retinoic acid on your skin (which is the prescription form of the drug.) At neutral pH the enzymes on your skin are reasonably effective at this conversion but if you alter the pH by combining an acid with the retinoid, the amount of all-trans retinoic acid is reduced and the product is simply not as effective. In addition, you may experience increased skin irritation.
So Paula is right – you can combine retinoids with AHAs/BHAs (it won’t cause your face to explode or anything horrible like that.) But you shouldn’t combine them because you won’t get the optimal effect from the product.
Click here to read Nicki’s full response on using Retinoids with AHA, BHA, and L-Ascorbic Acid.
{ 9 comments… read them below or add one }
Avene Triacneal has Retinaldehyde with Glycolic Acid (6%) in its formulation and it seems to work…. I always thought applying BHA or AHA first will help the retinoids penetrate better.
thanks for this. I saw this info somewhere before and started doubting what I thought was a fact
would this mean washing your face reduces the effectiveness as well as we’re washing away the all-trans retinoic acid from our skin?
@Ally: Do you mean washing your face after applying a retinol product? Yeah I imagine that would reduce efficacy.
before. I’d imagine the skin would be clear of everything after washing, or do the all-trans retinoic acids reside in the skin and not on the surfice?
@Ally: I’m not sure I follow you but I think it works like this:
1. You start with clean skin and then apply a retinoid.
2. After application the enzymes naturally produced by your skin convert the retinoid to all trans retinoic acid.
3. The acid then interacts with skin cells to increase their turnover rate.
Does that help?
I am mystified by the expert response to this question.
The two enzymes that convert retinol and retinal (retinaldehyde) are located inside cells. Since cells have many mechanisms to maintain themselves at a steady state including regulation on pH (i.e. level of acidity or alkalinity) it is very unlikely that the levels of AHA, BHA or any other acid, except extreme formulations, are going to have any significant effect on the level of acidity inside cells. Therefore, co-application will not have any significant effect on conversion of the precursors to retinoic acid.
More relevant to the question are the following:
Is retinol more or less stable in the presence of weak acids? Ascorbic acid (vitamin C) is a slightly different case since it is an antioxidant and is often added slow oxidation.
Does increased acidity of the skin surface increase or decrease uptake of retinol into the living part of the skin?
@Judith: Thanks for the great follow up questions. Let’s see if Nicki from FutureDerm or one of our other Derm friends has a response.
Does it applies to tretinoin too?
@Priscilla: I believe it would since the mode of action is the same.