Which is the Right Acid for my Skin?

Facial acids are some of the most accessible, and beneficial, active ingredients you can use in your skincare routine. They can target a range of skin concerns, from acne breakouts and dullness to fine lines and hyperpigmentation. But with so many to choose from, in a variety of formulations, how can you be sure which is best suited to your skin goals?
Here’s our dermatology team’s guide to some commonly used face acids, which skin concerns they treat, and how to use them effectively in your routine.

What are face acids?

Put simply, face acids are chemical exfoliants. They work by speeding up natural skin cell turnover, causing dead cells to shed and reveal brighter, healthier new ones. The result? Faded dark spots, even skin texture and visibly reduced fine lines.
Chemical exfoliants tend to be gentler than physical exfoliators, so we recommend using them over harsher brushes and scrubs, which can damage your skin.

Types of acids

Every acid has a distinct chemical composition and unique properties which make it more suitable for treating certain skin concerns than others. Here are some of the most common ones.

AHAs

AHAs, or alpha-hydroxy acids, are water-soluble acids that enter your skin and loosen the bonds between cells, allowing dead cells to shed from the skin surface. [1] Commonly used AHAs in skincare are glycolic acid, lactic acid and mandelic acid. Of these, glycolic acid has the smallest molecule size, meaning it penetrates the skin faster and deeper than acids with larger molecules. But, it may cause irritation when you first use it, especially if you have sensitive skin. Mandelic and lactic acid are usually more suitable for sensitive skin as their molecules are larger, making them gentler on your skin.

Azelaic Acid

Azelaic acid is found naturally in yeast. A proven multitasker, it helps exfoliate dead skin cells, as well as providing your skin with antioxidant and anti-inflammatory support. This results in unclogged pores, reduced redness, and visibly improved fine lines. [2]

BHAs

BHAs (beta-hydroxy acids) are oil-soluble, which means they penetrate deeper than AHAs. So alongside the usual cell turnover facial acids promote, they have the added benefit of dissolving sebum, the natural oil your skin creates which, in excess, can cause acne. [3] The most common BHA is salicylic acid, which you’ll often find in acne-fighting cleansers, toners and pimple patches.

Kojic Acid

A recent development in science-backed skincare, kojic acid is derived from mushrooms and works by binding to copper found in tyrosinase, a key enzyme involved in melanin production. This binding prevents your skin cells from producing melanin, making it effective at fading pigmentation, melasma, and uneven skin tone. [4]

PHAs

PHAs, or polyhydroxy acids, in skincare come from the same family as AHAs. The difference is, their molecules are a lot larger, so they can’t penetrate far beyond the skin surface. They’re still effective chemical exfoliants, but because they work more superficially than other acids, they may cause less irritation and suit those with sensitive skin. [5]

Tranexamic Acid

A synthetic derivative of lysine, tranexamic acid is thought to block the interaction between skin cells and melanocytes. These are the cells that create pigment, and when they produce too much, they result in hyperpigmentation. By reducing this, tranexamic acid can be effective at fading dark spots and enhancing your skin’s natural glow. [6]

Vitamin C (ascorbic acid)

Ascorbic acid, a pure form of Vitamin C, is an antioxidant with multiple skincare benefits. Aside from boosting skin brightness, it also helps shield your skin from UV damage and air pollution, which both contribute to skin ageing. [7] We use the most potent form, L-Ascorbic acid (L-AA), in our Vitamin C 15%: Fresh Batch Ascorbic Acid to give you the maximum skin benefits.

So, which acid is best for different skin concerns?

This is what our dermatologists recommend.

Acne and congestion

Recommended acids: AHAs (glycolic acid, mandelic acid, lactic acid), BHAs (salicylic acid)

The best acids for acne-prone skin are AHAs and BHAs. By encouraging your skin to renew faster than it naturally would, these acids help clear away dead skin cells before they can clog your pores and contribute to breakouts. [1] Plus, salicylic acid has the benefit of breaking down excess skin oils, which clears even more congestion. [3]

By speeding up the cell turnover process, AHAs and BHAs can also help improve both your skin texture and the appearance of acne scars, resulting in a more even skin complexion. [1, 3]

Dullness

Recommended acids: AHAs, Vitamin C (ascorbic acid)

If you’re looking to enhance your skin’s natural glow, AHAs and Vitamin C are our recommendations.
When AHAs break down the dull dead skin cells on your skin’s surface, they reveal the newer, brighter cells underneath. [1] Removing this build-up also helps other actives in your routine penetrate deeper, making them more effective.
Vitamin C, meanwhile, can improve skin tone by fading dark spots, sun damage and discolouration, leaving you with glowing, radiant skin. [8]

Pigmentation

Recommended acids: glycolic acid, kojic acid, tranexamic acid

The best acids for hyperpigmentation can help you fade post-acne marks, UV damage and melasma, creating a more even skin tone.

Glycolic acid, an AHA, gently exfoliates dead skin cells and speeds up the production of new ones, which can help reduce dark spots. [9]

As we’ve mentioned, kojic acid works by binding to copper in the pigment-producing enzyme, helping to reduce the amount of melanin it creates. [4]

We’re still not sure exactly how tranexamic acid works to fade hyperpigmentation. It’s thought to help slow down your skin’s melanin production and reduce blood flow that contributes to increased skin temperature, inflammation, and eventually hyperpigmentation. [10]

Ageing

Recommended acids: azelaic acid, AHAs, Vitamin C

Azelaic acid and vitamin C both have powerful antioxidant properties that target free radicals: harmful molecules caused by UV radiation and pollution that accelerate signs of skin ageing. They can also help treat existing damage, improving the appearance of dark sport and fine lines. [2, 7]

Many people also use AHAs like glycolic acid for wrinkles due to their collagen-boosting benefits. They help to stimulate fibroblasts, cells that create collagen under the skin’s surface, which helps your skin retain its elasticity and appear visibly smoother. [11]

Rosacea

Recommended acid: azelaic acid

Research shows that azelaic acid can treat the redness associated with rosacea by helping reduce inflammatory lesions and stopping the overproduction of your skin’s natural inflammation regulators. [12]

Adding topical acids to your routine

Before introducing a new skin treatment, you should always check if they’re suitable to use alongside other active ingredients in your routine. If you’re a Dermatica subscriber, you can contact our expert team via your dashboard any time you need advice.

Find out whether a personalised formula could help you achieve your skin goals on our website.

References
1. Tang SC, Yang JH. Dual Effects of Alpha-Hydroxy Acids on the Skin. Molecules : A Journal of Synthetic Chemistry and Natural Product Chemistry [Internet]. 2018 Apr 10;23(4). Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6017965/
2. Sauer N, Małgorzata Oślizło, Brzostek M, Wolska J, Katarzyna Lubaszka, Katarzyna Karłowicz-Bodalska. The multiple uses of azelaic acid in dermatology: mechanism of action, preparations, and potential therapeutic applications. Postępy Dermatologii i Alergologii [Internet]. 2023 Jan 1;40(6):716–24. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10809820/
3. Arif T. Salicylic Acid as a Peeling agent: a Comprehensive Review. Clinical, Cosmetic and Investigational Dermatology [Internet]. 2015 Aug;8:455–61. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4554394/
4. Saeedi M, Eslamifar M, Khezri K. Kojic acid applications in cosmetic and pharmaceutical preparations. Biomedicine & Pharmacotherapy. 2019 Feb;110:582–93.
5. Gentili G, Perugini P, Stefano Bugliaro, D’Antonio C. Efficacy and safety of a new peeling formulated with a pool of PHAs for the treatment of all skin types, even sensitive. Journal of Cosmetic Dermatology. 2022 Aug 9;22(2):517–28.
6. Gaćina, K. (2023). The Use of Tranexamic Acid in Dermatology. Acta Clinica Croatica. doi: https://doi.org/10.20471/acc.2023.62.02.16.
7. Darr D, Dunston S, Faust H, Pinnell S. Effectiveness of antioxidants (vitamin C and E) with and without sunscreens as topical photoprotectants. Acta Dermato-Venereologica [Internet]. 1996;76(4):264–8. Available from: https://pubmed.ncbi.nlm.nih.gov/8869680
8. Telang PS. Vitamin C in dermatology. Indian Dermatology Online Journal [Internet]. 2013;4(2):143. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3673383
9. Almeman AA. Evaluating the Efficacy and Safety of Alpha-Hydroxy Acids in Dermatological Practice: A Comprehensive Clinical and Legal Review. Clinical, Cosmetic and Investigational Dermatology [Internet]. 2024 Jul 16;17:1661–85. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11268769/
10. Zhu JW, Ni YJ, Tong XY, Guo X, Wu XP, Lu ZF. Tranexamic Acid Inhibits Angiogenesis and Melanogenesis in Vitro by Targeting VEGF Receptors. International Journal of Medical Sciences [Internet]. 2020 Mar 25 [cited 2021 May 7];17(7):903–11. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7163366/
11. Narda M, Trullas C, Brown A, Piquero‐Casals J, Granger C, Fabbrocini G. Glycolic acid adjusted to pH 4 stimulates collagen production and epidermal renewal without affecting levels of proinflammatory TNF‐alpha in human skin explants. Journal of Cosmetic Dermatology. 2020 Jul 24;20(2):513–21.
12. van Zuuren EJ, Fedorowicz Z, Carter B, van der Linden MM, Charland L. Interventions for rosacea. Cochrane Database of Systematic Reviews [Internet]. 2015 Apr 28; Available from: https://www.cochrane.org/es/CD003262/SKIN_intervenciones-para-la-rosacea