What’s the big deal with Hydroxy Acids?

Diane Kruger by Patrick Demarchelier 1994
Diane Kruger by Patrick Demarchelier (1994)

The past few years have seen quite a turnaround when it comes to facial exfoliation, as physical scrubs have completely fallen out of favour and been replaced by exfoliating acids. Physical scrubs are not only far too rough, leaving behind “microtears” in the skin’s surface, but the tiny plastic beads used in some products are very environmentally damaging as they wash into the sea and don’t dissolve.

Chemical exfoliators, on the other hand, gently break down dead skin cells to reveal newer, softer, more even-toned skin. Within this category are two types of exfoliators:

Alpha Hydroxy Acids (AHAs)

AHAs work by reacting with the upper layer of the epidermis and weakening the bonds that hold dead skin cells together. This means they’re great for cell turnover, and in turn help to reduce the appearance of wrinkles, smooth and firm the skin, help with sun damage and pigmentation, and stimulate collagen production.

Generally speaking, at-home AHA products should have the relevant acid listed as the second or third product in the ingredient list which should mean that the concentration is high enough to be effective (ideally 5-10%).

Glycolic acid

Derived from sugar cane (although often made synthetically now), glycolic acid is the superstar of the chemical exfoliant family because of its small molecular structure that makes it easier for the skin to absorb. Glycolic acid has the ability to radically improve the overall appearance and texture of the skin.

Lactic acid

Known as the “hydrating acid”, this ingredient is a natural humectant that helps to hold water in the skin. It is gentler and less irritating than glycolic acid and is effective on acne-prone, dry and mature skin types, helping to reduce breakouts and signs of ageing.

Malic acid

Malic acid is found in apples and pears and when used in skincare it functions largely as a pH adjuster, rather than an exfoliator on its own. By raising the pH of the skin, this acid helps to facilitate healthy exfoliation and improve the effectiveness of any other ingredients it is paired with.

Citric acid

This AHA functions similarly to malic acid by affecting the skin’s pH, but is also a powerful antioxidant and skin brightener. It is particularly effective at reducing pigmentation and skin discolouration.

Tartaric acid

Found in high concentrations in grapes, cranberries and tamarinds, this ingredient is also a pH adjuster and is also good at unclogging pores (but not as good as salicylic acid – see below). Tartaric acid is less stable than glycolic and lactic acid, so it is less commonly used as an active ingredient in anti-ageing products.

Diane Kruger, source unknown
Diane Kruger, source & date unknown

Beta Hydroxy Acids (BHAs)

The only difference between AHAs and BHAs is that the latter is oil soluble, which makes them better suited for treating acne and congestion. There is also only one type of BHA in widespread skincare use and that is:

Salicylic acid

This BHAs unique selling point is its ability to penetrate the pore and therefore exfoliate from the inside out. Particularly well suited for oilier skin types, non-inflammatory acne and thickened skin conditions, salicylic acid is excellent for dealing with black- and whiteheads as they not only exfoliate the pores but have anti-bacterial and anti-inflammatory properties as well.

If you’re allergic to aspirin you shouldn’t use a BHA exfoliant because of aspirin’s close relationship to BHA. BHA is salicylic acid, while aspirin is acetylsalicylic acid.

My AHA and BHA products | All Dolled Up
My personal stash of AHA- and BHA-containing skincare

Product recommendations

REN Glycolactic Radiance Renewal Mask* (glycolic, lactic, citric and tartaric acids)
Clarins Gentle Exfoliator Brightening Toner* (low concentration of glycolic, salicylic and tartaric acids)
Clinique Mild Clarifying Lotion (salicylic acid)
Paula’s Choice Skin Perfecting 2% BHA Liquid Exfoliant* (salicylic acid – also available in 1%)
Dermalogica Gentle Cream Exfoliant* (salicylic and lactic acids)
Smashbox Photo Finish More Than Primer Blemish Control* (2% salicylic acid)
Environ Sebutone (salicylic and lactic acids)
NeoStrata Ultra Daytime Smoothing Cream (glycolic and citric acids)
Paula’s Choice RESIST Weekly Resurfacing Treatment (10% glycolic acid – also available in 5%)

*These products I have used and would personally recommend.

NB: If you’re a regular user of AHAs and BHAs, it’s even more important to use a good daily SPF as your skin will be even more sensitive to the effects of the sun.

Further reading:
How to Exfoliate Skin (Paula’s Choice)
What are AHAs and BHAs (Murad)
Top 10 Acid Toners (Caroline Hirons)

10 comments on What’s the big deal with Hydroxy Acids?

  • Debs

    Awesome blog post! Thanks so much! Have been wanting to try the Environ Sebutone for ages- you have convinced me 🙂

    • Debs

      In your experience- is the Environ Sebutone quite drying?

      • Jules (author)

        I haven’t used it personally – I’ve only used the products highlighted with an asterisk.

        • Debs

          Whoops- didn’t see that part. Thanks for clarifying.

  • Prettiful Blog

    Such an informative post, thank you very much! I love the REN Mask, one of my faves! Have you tried the REN AHA concentrate?

    • Jules (author)

      I haven’t actually but it looks great – heavy on the lactic acid so nice and hydrating, and in my experience the brand is very trustworthy.

  • The Spruce Girls

    Such a great post – i’m battling with congestion on my chin, so I’m keen to try the Paula’s Choice Liquid Exfoliant! Did you find it to be quite a beneficial product?


    • Jules (author)

      Yes! It is excellent. I’m actually really impressed with everything I’ve tried from Paula’s Choice.

  • Lauren

    Thanks SO much for this, it’s really great!
    I loved using the Dermalogica cream exfoliant (good results, slight redness), but the Paulas Choice review on it was so chilling that I stopped. Urgh! So maybe must give her one a whirl. Thanks for the other recommendations too 🙂

    • Jules (author)

      Paula’s Choice reviews of any products other than her’s are ALWAYS completely scathing so don’t take it too seriously. Having said that, PC’s products work very well for me.

Leave a Reply

Your email address will not be published. Required fields are marked *