Hi Charlotte, can you actually use AHAs and Retinol in the same routine? I've been given so much conflicting advice!
I get so many questions about this every week! While I personally have used AHAs and retinol in the same routine without having any issues - I wanted to double check so I spoke to a dermatology colleague I used to work with.
It seems the mass confusion about using retinol with AHA products has to do with concern over the exfoliant lowering the skin's pH, therefor stopping the retinol's ability to work its magic. The thought behind this is because if pH of the skin is below 5.5 to 6, an enzyme in your skin won't be able to convert the retinol into retinoic acid which is the active version of retinol. This is based on the assumption that the acidic exfoliant ingredients lower the pH of the skin, but isn't what actually happens. There was a study in 1999 which appears to be the root of this confusion - but the study was conducted on both animal and human samples and the pH was only affected after the addition of 'a fatty acid by-product'. The journal concluded "no clear optimal [pH range] was seen when the assay was run without [fatty acid byproduct]."
Research has actually shown that retinol combined with chemical exfoliants like AHAs helps to fade hyperpigmentation, and improves the results seen from both ingredients on the skin.
The thought that skin's pH could somehow cancel acidic skin-care products applied to the surface is wrong. A neutral pH is 7, but skin is naturally acidic. The skin's pH is actually between 4.7 and 5 - yet we know from studies that retinol works when applied to the skin, and it works at the skin's naturally acidic pH.
So to answer your question - it is fine to use these two amazing ingredients together, but as always keep an eye on what’s going on with your skin as everyone will react differently. You'll want to keep an eye on hydration levels in the skin as both can be slightly drying. Normal to oily skin types should have no issues but if you’re on the drier or more sensitive side, start with a simple glycolic acid and give your skin time to adjust by using just a couple of times a week to begin with. I like to use our Balancing Mist geranium water between products which has a pH of around 5 and is super soothing.