In the August Q&A on Patreon, Mildred asked: Question pls: Can I use a glycolic toner followed by a Retin A cream? I read a blog that these two needs to be used on alternate days but I can't seem to find that writing any more.
And Mercedes asked: I would like to know more about using Vitamin A and its derivatives in different products. I know some things are medical grade, but I mean things like retinols and learning which suits which skin types the best.
I found this great interview with Dr Leslie Baumann, creator of the Baumann Skin Type Indicator, which I write about a lot in the skin chemistry section of the blog. That's the one that looks at a few different variables - dry or oily, resistant or sensitive, and so on. It's a great system!
“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 (AHA), and salicylic acid and kojic acid can break down retinol and retinoids.” Retinoids and acids simply function better when applied separately. This is because of a two-part enzymatic oxidation process in which retinol is converted within your skin to become active: Ffirst to retinaldehyde, then to all-trans retinoic acid. Retinol oxidation is optimized at a neutral pH (Nature). This is because the enzymes responsible for this oxidation, called retinol and retinal dehydrogenases (DHs), are most active at this pH. So don’t mix retinoids and acids"To try answer your question, Mildred, no, it doesn't sound wise to use one after the other. It does sound like you can use one in the morning and one at night. But I would be very careful as some skin types can handle neither acids nor Vitamin A, so please do series of test patches on a small piece of your skin before undertaking this skin care routine. (Maybe do it over two weeks so you can see the long term impact?)
So if you mix retinol with acidic products, there will be suboptimal conversion of retinol to its active form within the skin. Will you still notice some effects? Sure. But for best results, use acidic products during the day, and retinol at night. (From FutureDerm)
To try to answer your question, Mercedes, it sounds like any form would work well for any skin type - I couldn't find anything about specific skin types and which forms would be more effective, which usually means there isn't much if anything on that topic - but it seems like retinol is the most effective version when used at as little as 1%.
I'll refer you over to the FutureDerm site to read a bit more about retin-type ingredients and your skin. This is a company that makes products, so take it with a grain of salt, but there is some interesting stuff on that site.
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