Ask Apothaka: can I use lactic acid with tretinoin/retinoids?

Posted by Natasha Dauncey on

I often get product-related questions from my lovely customers and I thought they'd make great prompts for blog posts, so welcome to my new mini-series where I'll share my answers to customers' product questions, as I suspect others may find these useful!

A customer recently asked:

"I've noticed that lactic acid is listed as an ingredient in your skin quenching essence, will using this exacerbate the irritation caused by the tretinoin I'm currently using?"

This is a very sensible question to ask because I usually advise customers to avoid using exfoliating actives when their skin is adjusting to tretinoin (or other retinoids), as the skin barrier is more likely to get disrupted. However, in the case of skin quenching essence, formulation is key - it's not an exfoliating product despite the presence of lactic acid! But how is this possible?!

What typically drives the potency (and therefore likelihood of irritation) of an exfoliating acid-based product is the concentration of the acid used, as well as the pH. Products designed to encourage exfoliation tend to have a very low pH and use a reasonable amount of acid (in the case of lactic acid, usually in the 5-10% range for at-home products).

Lactic acid in particular is a multifunctional ingredient - at higher concentrations, it obviously functions as an exfoliator, but at lower concentrations (and at a higher pH), it functions as a humectant instead - hydrating the surface layer (stratum corneum) of the skin. In fact, lactic acid is naturally part of our own skin's Natural Moisturising Factors (NMF), and in our own skin it also naturally serves to hydrate (rather than exfoliate the skin). 

Going back to my skin quenching essence specifically, the level of lactic acid in this formulation is extremely low (that's why it's listed towards the end of the ingredients list) - it's actually part of the proprietary hydration complex blend in the formulation, which is designed to mimic the skin's NMF. At the level it's used at in here, it won't have an exfoliating effect but instead it's designed to function as a humectant (hydrating) ingredient. 
Furthermore, the pH of the overall formulation is at a skin friendly pH of 5-5.5. This again ensures that the lactic acid doesn't function as an exfoliator but more as a humectant, so it's nothing like a typical acid exfoliating toner. 
In short, the presence of lactic acid in my skin quenching formulation doesn't make it exfoliating, but more hydrating - and therefore it can be used safely alongside tretinoin / other retinoids to combat the dryness often caused by retinoid use. I would still avoid using any products formulated to exfoliate when you're adjusting to retinoids as this is likely to cause irritation / skin barrier disruption.
If you have any other questions you'd like me to answer, send me an email: Remember, Apothaka is here to support your skincare journey (and your skin barrier 😉). Check out my skin quenching essence here.


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