With thousands of different ingredients on the market that are helmed to revitalise your skin, it's easy to be confused as to what your visage actually needs. The ingredient list of skincare products are often saturated with obscure chemicals and even rarer natural elements, of which their benefits can only be understood with the help of a medical textbook. For that reason, we've asked for guidance from skincare savant, Katie Service, who'll be breaking down common beauty ingredients in our new series, Dermatology Diaries.

Described by Sarah Jossel as "The new skincare beauty bible", her new book The Beauty Brief: An Insider’s Guide to Skincare shares Service's tips and tricks, including case studies of global best-sellers, in-depth analysis of different dermatological treatments and SOS skin repair. Currently the Editorial Beauty Director at Harrods, and having worked with world-famous makeup artists such as Charlotte Tilbury, she is one of the best in the business to be answering any beauty-sphere queries. 

This week, Katie breaks down AHAs and BHAs, explaining what their benefits are, how and when to use them and what are her favourites on the market. 

Not the sexiest sounding ingredients, Alpha Hydroxy Acid and Beta Hydroxy Acid are actually pretty awesome. They are both chemical exfoliants that help to speed up the natural skin process we call ‘cell turnover’, which is essentially the loosening and shedding of dead skin cells from the top layer of our skin with the purpose of revealing the fresher, younger cells underneath. They aren’t necessarily expensive and they are great, easy to use ingredients that can solve a number of pesky skin issues like blocked pores, dull skin, pigmentation and mask-ne in just a couple of uses.

AHAs and BHAs may sound similar, but it’s important to note that they act a little differently to achieve their similar goal. AHAs (some which you may have heard of are glycolic, mandalic and lactic acid) work on the surface of the skin, loosening the 'glue' that holds the dead skin cells together so that they can be lifted off.  The skin that is left behind tends to look clearer, firmer and more, even with a smoother texture – they even help to soften the look of fine lines or crepey skin over time. Using an AHA will help your moisturiser and serums penetrate the skin better as well which is a big win.  BHAs on the other hand work a little deeper in the skin and pores, they are oil soluble and do a great job and decongesting the pores, making them look smaller and minimising the risk of blemishes – so good for mask-ne. An example you may have heard of is Salycilic Acid – if you are suffering a case of lockdown acne then this is the ingredient to reach for, for sure.

There aren’t many downsides to AHAs and BHAs on paper, they make for a smart and efficacious addition to most skincare regimes – it’s how you use them (or misuse them) that can take you back a few steps. In skincare, more isn’t always more, and it’s not always the best idea to use them daily or together as this can be aggravating to your skin. Especially if it’s already under physical stress (masks, pollution, blue light, etc) or under the instruction of other exfoliants like physical scrubs and Retinoids. (When we have bad skin we tend to throw the book at it and sometimes it’s better to slim things down and be selective about the ingredients we treat it with!)  So, think about what your skin needs – if it’s a gentle polish to cast off dullness/look fresher then AHAs are your fix, and if it’s deeper decongestant work then turn to BHAs. Some skinthusiasts do experiment with cycling between them – using one in the morning and one in the evening, which you can try but take it slow, listen to your skin and be gentle.

So, what about skin thinning? There is lots on the internet (from dermatologists, scaremongers and skinfluencers alike) to say that skin thinning is a negative result of overusing AHAs and BHAs. My take would be that this depends on the concentration and regularity of use – over the counter concentrations and moderate use no problem.  Hydroxy acids only work on the very upper layers of dead skin in the stratum corneum anyway – not the full depth of the skin, and as long as you're using lovely moisturising ingredients that support the skin barrier in your serum and moisturiser, then you shouldn’t run into any problems. Another potential negative is that by removing the top layers of dead skin cells you leave yourself a little more vulnerable to sun damage, so counterbalance with a great SPF.

My favourite three products that contain Hydroxy Acids? Pixie Glow Tonic, La Roche-Posay Effaclar Duo+ and iS Clinical Cleansing Complex.

Shop The Beauty Brief: An Insider’s Guide to Skincare by Katie Service, published by Thames & Hudson here.

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