In this article:
Alpha hydroxy acids (AHAs)
Beta hydroxy acid (BHA or salicylic acid)
Hyaluronic acid
Ascorbic acid
Amino acids
Retinoic acid
Fatty acids
Tranexamic acid
Azelaic acid
The concept of using an acid on skin sounds scary. Acids can’t be good for skin, right?
As it turns out, there are many acids that are wonderful for skin. In fact, adding acids to your skin care routine can transform your skin in ways that will truly impress, no matter your skin type, age, or skin concerns.
At Paula’s Choice, we know our skin care acids. That’s why we’ve rounded up the acids that mounds of research have shown are great for skin. We explain what they are, how they work, and who they’re best for so you’ll know which acids are right for you!
Alpha hydroxy acids (AHAs)
What are alpha hydroxy acids?
Alpha hydroxy acids are a staple in any well-rounded skin care routine. AHAs are a group of ingredients that include glycolic, lactic, malic, tartaric, mandelic, and citric acids. All of them can be effective for exfoliating skin, but among them, glycolic and lactic acids are considered the most effective. Citric acid is generally not a top pick for AHA exfoliation because it’s too acidic (think lemon juice).
How do alpha hydroxy acids work?
When properly formulated—meaning within the correct pH range for the acids to be effective—AHAs work to unglue the “cement” that anchors dead, dull skin to the surface, keeping it from shedding naturally and promoting dead cell buildup. Left unchecked, this buildup leads to dull, rough skin that loses its youthful smoothness, even tone, and glow.
Who are alpha hydroxy acids for?
All skin types can benefit from AHAs, due to their gentle nature and humectant properties. However, they’re best for normal to dry skin showing visible signs of sun damage.
What benefits will I see?
Regular use of AHAs reveals smoother, softer, visibly firmer, and more even-toned skin with fewer signs of sun damage, including fine lines and wrinkles.
Glycolic acid, the powerhouse of AHAs, is found in in several Paula’s Choice Skincare products, including the RESIST Advanced Smoothing Treatment 10% AHA and RESIST Daily Smoothing Treatment 5% AHA.
Lactic acid and mandelic acid, top tier AHAs, appear alongside one another in our SKIN PERFECTING 6% Mandelic Acid + 2% Lactic Acid Liquid Exfoliant.
Beta hydroxy acid (BHA or salicylic acid)
What is beta hydroxy acid?
There’s only one beta hydroxy acid, and that’s salicylic acid. It’s a multitasking ingredient used in skin care for decades because it’s amazingly effective.
How does beta hydroxy acid work? When properly formulated—meaning within the correct pH range for exfoliation—BHA works similarly to AHAs to exfoliate skin’s surface and hydrate. However, because BHA is oil soluble (AHAs are not), it penetrates the pore lining, where it works to dissolve clogs that lead to bumps and blemishes on skin’s surface. BHA also has a natural ability to calm skin, so it’s preferred for those with sensitive skin. Its gentleness makes it suitable even for rosacea or milia-prone skin.
Who is beta hydroxy acid for?
All skin types can benefit from BHA, but it’s best for normal to oily or combination skin that has blemishes, bumps, clogged pores, overly sensitive skin, or post-blemish marks.
What benefits will I see?
Daily use of salicylic acid can refine pore size, alleviate bumps and clogs, soften the look of wrinkles, improve skin texture, tone, and hydration, and restore a gorgeous glow (6). See what we mean by “multitasking"?
You’ll find salicylic acid in several Paula’s Choice Skincare products, including our best-selling SKIN PERFECTING 2% BHA Liquid Exfoliant and RESIST Advanced Pore-Refining Treatment 4% BHA as well as in our sensitive skin focused CALM 1% BHA Sensitive Skin Exfoliant.
Hyaluronic acid
What is hyaluronic acid?
Hyaluronic acid is a glycosaminoglycan, a fancy name for a vital natural substance that’s a youth-supporting part of skin. With age and cumulative sun damage, our skin’s natural supply of hyaluronic acid decreases.
How does hyaluronic acid work?
Hyaluronic acid has restorative abilities and can boost skin’s moisture content, soothe skin, and defend against moisture loss. It can hold up to 1,000 times its own weight in water, by bonding water to tissue, making it an optimal hydrator for all skin types. Want more? It’s also a skin-calming antioxidant.
Who is hyaluronic acid for?
All skin types can benefit from hyaluronic acid, as well as from its salt form, sodium hyaluronate.
What benefits will I see?
You’ll see smoother, perfectly hydrated skin plus a plumped appearance to bothersome fine lines and wrinkles, including around the eyes.
You’ll find hyaluronic acid in many Paula’s Choice Skincare products, including in Hyaluronic Acid Booster and the RESIST Ultra-Light Super Antioxidant Concentrate Serum.
Ascorbic acid
What is ascorbic acid?
Ascorbic acid is another name for pure vitamin C, an ingredient that occurs naturally in our skin and in many foods.
How does ascorbic acid work?
Ascorbic acid is a superstar for its proven antioxidant properties that help defend skin from environmental assault by thwarting elements—including pollution—that progressively weaken skin’s surface, chipping away at a youthful appearance.
Who is ascorbic acid for?
All skin types can benefit from ascorbic acid and its non-acidic derivatives, such as ascorbyl glucoside, tetrahexyldecyl ascorbate, and several others.
What benefits will I see?
Your skin will take on a smoother, firmer look as signs of wrinkles, uneven skin tone, and dullness seem to fade. Ongoing use keeps skin looking bright, healthy, and resilient.
You’ll find ascorbic acid in our C15 Super Booster.
Amino acids
What are amino acids?
Simply put, amino acids are the building blocks of protein. Our skin’s surface is composed primarily of proteins, and proteins wouldn’t exist to create skin without amino acids.
How do amino acids work?
In skin care products, amino acids act as water-binding agents; some also have antioxidant and calming properties (7). Because they occur naturally in skin, they’re easily recognised and put to good use with other beneficial ingredients.
Who are amino acids for?
Amino acids are great for all skin types, as they’re naturally occurring in skin and non-irritating.
What benefits will I see?
Due to their water-binding capacity, you’ll see and feel smoother, more supple, and hydrated skin from amino acids like proline, leucine, arginine, and serine.
You’ll find amino acids in many Paula’s Choice Skincare products, including EARTH SOURCED Purely Natural Refreshing Toner.
Retinoic acid
What is retinoic acid?
Retinoic acid is what gold standard anti-ageing ingredient retinol is converted to when applied to skin. This is the form of vitamin A that has a natural affinity for skin.
How does retinoic acid work?
Once retinol is converted to retinoic acid, it works in numerous ways by “talking” to elements within skin’s surface that are misbehaving. After this “talk,” skin steadily shows signs of improvement.
Who is retinoic acid for?
Retinoic acid is ideal for those struggling with multiple signs of ageing, blemishes, and other signs of skin behaving badly. Think of it as the personal trainer that gently gets skin back to looking and feeling its best.
What benefits will I see?
Over 40 years of established research shows that retinoic acid helps visibly increase the appearance of firmness, diminish the look of fine lines and wrinkles, significantly improve uneven skin tone, smooth and refine the surface of skin (yes, that includes pores), and bring the look of skin to a healthier state (3).
You’ll find retinol in several Paula’s Choice Skincare products, including our CLINICAL 1% Retinol Treatment.
Fatty acids
What are fatty acids?
Fatty acids are naturally occurring ingredients that are a vital part of a smooth, healthy, and vibrant skin barrier. Examples include oleic, palmitic, linoleic, and linolenic acids.
How do fatty acids work?
Skin easily recognises fatty acids, putting them to work right away to replenish and reinforce its barrier (surface), strengthening it against moisture loss and signs of environmental damage (8). Many fatty acids also soothe skin, allowing it to become visibly calmer and less reactive.
Who are fatty acids for?
Fatty acids are essential nutrients for skin. As such, they’re brilliant ingredients for all skin types, especially dry to very dry and sensitive skin.
What benefits will I see?
You’ll see a noticeable increase in skin’s hydration, softness, and ability to bounce back from environmental stressors that would normally send skin into a troublesome tailspin.
You’ll find fatty acids in many Paula’s Choice Skincare products, such as our Omega+ Complex Serum and RESIST Advanced Replenishing Toner.
Tranexamic acid
What is tranexamic acid?
Tranexamic acid is a synthetic analogue (meaning similar) to the amino acid lysine. It was originally used orally for certain bleeding disorders, but a serendipitous result was observed: people taking tranexamic acid for one problem found it also helped solve stubborn skin discolourations. Thus, research into using this ingredient topically began and has shown impressive results in tackling discolouration when used in concentrations between 2–5%.
How does tranexamic acid work?
Tranexamic acid muscles in on two pathways that, without such interference, would set the stage for skin’s surface to see discolourations, including a patchy, mask-like discolouration known as melasma (2). It also has a soothing effect which helps reduce signs of redness due to environmental exposure or minor skin irritations.
Who is tranexamic acid for? Tranexamic acid is suitable for all skin types. As with all bio-active ingredients, take extra care if you have very sensitive, reactive skin. It’s an ideal ingredient to target multiple types of hyperpigmentation and works particularly well when paired with niacinamide.
What benefits will I see?
With once or twice-daily usage of a product that contains between 2–5% tranexamic acid, you’ll see steady improvement of discolourations, including dark spots and post-breakout marks. It's even suitable for melasma-prone skin. You’ll also see a more clarified, even skin tone. Reminder: Discolouration improvement also depends on daily use of a sunscreen.
Azelaic acid
What is azelaic acid?
Azelaic acid is a multitalented ingredient that can be derived from grains such as rye or barley, although skin care formulations typically use lab made forms. When used in concentrations of 5% or more, it plays a role in visibly reducing redness, dark spots, bumps and rough texture.
How does azelaic acid work?
Azelaic acid is tricky to formulate into skin care. In its pure form, it has trouble staying evenly blended throughout a formula and faces limitations when it comes to penetrating skin. But in the right formulation, it instantly interrupts various factors within skin that lead to signs of sensitivity, blemishes and many types of discolouration.
Who is azelaic acid for?
All skin types can benefit from azelaic acid, but it’s best for those with blemishes, bumps, clogged pores, redness or discolourations. Its mild exfoliating properties make it ideal to pair with salicylic acid as used to address bumps and blemishes.
What benefits will I see?
Routine use of azelaic acid will soothe skin, diminish stubborn spots (including post-blemish marks), softly refine texture, promote a more even, radiant-looking skin tone and serve as an additional source of antioxidants.
You’ll find azelaic acid in Paula’s Choice Skincare’s 10% Azelaic Acid Booster.
The acids described above are some of the most beneficial for skin, as demonstrated through research and clinical studies. However, there are other acids that are also worth seeking out and incorporating into your skin care routine. Examples are antioxidant acids such as alpha lipoic acid, ferulic acid, and ellagic acid; brightening ingredients like kojic acid; and soothing glycyrrhetinic acid from licorice. They’re suitable for most skin types and found in select moisturisers, serums, and toners.
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Ready to dive into different ingredient categories? Learn more about other skin care ingredients.
References for this information:
- Pharmaceutics, March 2021, pages 1–8
- Clinical and Experimental Dermatology, June 2020, pages 445–449
- Archives of Dermatological Research, May 2017, pages 275–283
- Journal of Clinical and Aesthetic Dermatology, October 2015, pages 21–26; and March 2009, pages 38–43
- Journal of Drugs in Dermatology, September 2015, pages 1–8
- Clinical, Cosmetic, and Investigational Dermatology, August 2015, pages 455–461; and November 2010, pages 135–142
- Amino Acids, June 2012, pages 2,481–2,489
- Clinics in Dermatology, July-August 2010, pages 440–451
