Acids Decoded & Why You Should Use Them Head To Toe
The chemical exfoliants can benefit more than just your face. The best bit? Acids might just be the answer to the most common of your skincare troubles: acne, pigmentation, uneven skin tone and rough texture.
First things first, what are all these acronyms? The world of acids can be divided into a few categories, three to be precise: Alpha Hydroxy Acids (AHAs), Beta Hydroxy Acids (BHAs) and the underdog, Polyhydroxy Acids (PHAs). If you're using a skincare acid, it'll fall into one of these three categories.
When it comes to skincare, the face gets a lot of attention. No matter how many steps are in your routine, there’s a good chance you have multiple serums, moisturizers, masks, and more to choose from depending on your skin concerns at any given time. But your skin doesn’t stop at your jawline or even décolleté. The body’s largest organ stretches from head to toe, and it is just as susceptible to dark spots, acne, uneven skin texture, and laxity below the neck as it is above it. That means your body care routine should (a) exist and (b) be catered to your skin type.
The best way to curate a body care routine is to treat it like a facial skincare routine and pay attention to the ingredients in the products and the formats that work best for your lifestyle. One class of active ingredients that work just as well for face as they do for body are hydroxy acids (i.e. alpha, beta, and poly). They are chemical exfoliants that help remove dead skin cells from the top layer of your skin. They are great for anyone that wants to get rid of dead skin cells, promote skin radiance, reduce visible sun damage, reduce dryness, smooth skin texture, prevent blemishes, reduce fine lines and wrinkles, and enhance youthful appearance. Need we say more?
What Are Hydroxy Acids?
Hydroxy acids are part of the family of carboxylic acids. They are considered chemical exfoliants because of their ability to, well, chemically exfoliate the skin. Chemical exfoliants help dissolve the ‘glue’ that bonds epidermal skin cells together. Their use helps lift away dead skin cells, leaving a smooth texture and renewed glow to dry, rough, or bumpy skin. There are three types of hydroxy acids in skincare. While each has the ability to exfoliate the skin, there are key points of difference. What differentiates these particles is specifically particle size along with molecular features.
Alpha Hydroxy Acids (AHAs): AHAs, which include glycolic, lactic, and more, are water-soluble acids derived from sugary fruits that act as chemical exfoliants. They remove dead skin cells from the top layer of your skin so that new, more evenly pigmented cells may take their place. AHAs can help loosen clogged pores to treat and prevent acne and yield brighter, more youthful-looking skin.
You can find them mixed in with serums, creams, cleansers and toners, depending on how high of a dosage you want to use (the smaller the percentage, the less potent the formula.
Beta Hydroxy Acids (BHAs): In skincare, salicylic acid is mainly what we’re referring to when speaking about BHAs. The oil-soluble acid is often used for oily and acne prone skin, as its smaller size allows it to penetrate more deeply into pores.
AHAs are ideal for those concerned with ageing skin, whereas BHAs are best for those who are one the oilier side of the skincare spectrum and struggle with acne, blackheads and milia (the little white bumps you sometimes see under the skin).
Polyhydroxy Acids (PHAs): PHAs like gluconolactone tend to be similar to AHAs but with a larger molecular structure. The molecules that make up PHAs are much larger in size, which means they cannot penetrate skin as deeply as traditional AHAs and BHAs. Instead, they work exclusively on the skin's surface without disturbing the delicate layers that lie beneath. This ensures optimum skin renewal with minimal irritation. PHAs are great for those with dry, sensitive skin with a little pigmentation.
If you grew up using physical scrubs to exfoliate, you might be wondering what all the hype around chemical exfoliants – specifically, hydroxy acids – is about. Unlike your typical gritty exfoliating scrub, AHAs, BHAs, and PHAs offer multiple benefits. For example, mandelic acid is an AHA derived from bitter almonds that not only gently exfoliates the skin but also evens out skin tone, lightens discoloration, banishes acne scars, and stimulates collagen. The oil solubility of salicylic acid means it penetrates deeper, ideal for deeper cleansing, and is also a great acne treatment,.
On their own, these acids can treat an array of skin concerns, but they can be even better together. AHAs, BHAs, and PHAs all have their unique benefits but what makes them all so wonderful is that they can be used alone as individual actives or combined to provide more benefits. A combination of all three family members makes for a superior chemical exfoliant. Each can also be further customized to treat a specific concern based on its potency (there are both professional and over-the-counter strengths) and product type. They come in different strengths, so they can be as gentle or as active as one may need them to be, as well as in different products such as cleanser, toners, serums, and moisturizers.
AHAs vs. BHAs vs. PHAs
Now that you have an intro to hydroxy acids, it’s time to dig a little deeper. In a nutshell, AHAs are great for normal to combination skin types, and BHAs are best for those with oily, acneic, inflammation, sun damaged, and acne-scarred skin, as it penetrates and works deeper than AHAs and PHAs,
ALPHA HYDROXY ACIDS (AHAS)
The Skinny: Alpha hydroxy acids are water-loving acids that exfoliate the outer layer of skin by dissolving the bonds between skin cells. Derived from fruits, nuts, sugars, and milk, AHAs are considered gentle as they have a large molecular structure that doesn't allow for a deep penetration but rather sits on the surface.
Read the Label: The most common AHAs are glycolic acid, lactic acid, citric acid, mandelic acid, and benzilic acid.
How They Work: Alpha hydroxy acids are used in cosmeceuticals for a variety of clinical endpoints including exfoliation, stimulation of collagen synthesis, improving the elasticity of fibers in the skin, moisturization, and acting as an antioxidant-based preventative measure from photoaging. Of all the hydroxy acids, AHAs are the best for anti-aging.
Ideal Candidate: AHAs are generally suitable for all skin types, They may, however, be especially appropriate for those with dry skin, age-related skin concerns, or surface-level concerns like acne or acne scars. AHAs are ideal for those with discoloration, fine lines, acne scars, dark spots, and rough texture and are marketed for all skin types.
How to Use: You can have too much of a good thing. Since AHAs act as exfoliants, you should incorporate them into your routine slowly. You should use them once a week to start and building up to every other day if, and only if, your skin can handle it. Sensitive skin may be more receptive to products that have lower levels of AHAs, especially at first. Avoid using AHAs too often, as over-exfoliating can lead to irritation and redness. Also, introducing them into your routine at a lower percentage – between four and 15 percent – and increasing from there.
BETA HYDROXY ACIDS (BHAS)
The Skinny: ‘BHA’ stands for beta hydroxy acid and is often derived from willow bark, sweet birch bark, and wintergreen leaves. Much like AHAs, BHAs work to exfoliate the surface of the skin, however, they also have soothing properties that work inside the pores.
Read the Label: Salicylic acid is the smallest [molecule] and, therefore, can dive deep into the pores of the skin.
How They Work: While AHAs can only exfoliate the skin's outer surface, a BHA like salicylic acid can go deep into the pores of the skin to dissolve desmosomes – the bond that holds skin cells together. As such, adding BHAs to a skincare routine can also reduce the rate of skin-cell shedding and help dissolve oil and keratin plugs.
Ideal Candidate: Often used to fight sun damage and acne, BHAs get into the hair follicles and help remove excess oil and dead skin. Because of this, BHAs like salicylic acid work best with combination to oily skin types.
How to Use: Beta hydroxy acids are oil-loving and penetrate deeper, which makes them ideal for acneic, oily, and sun-damaged skin types,” Aguilar notes. Salicylic acid is one of three active ingredients (along with benzoyl peroxide and sulfur) approved by the United States Food and Drug Administration (FDA) for use in over-the-counter acne products. While they are available in different potencies, low concentrations of it can help calm sensitive skin.
POLY HYDROXY ACIDS (PHAS)
The Skinny: Similar to AHAs, polyhydroxy acids are the newest breed. PHAs are larger in size compared to AHAs but share the same benefits making them ideal for those with combination, sensitive, or acneic skin.
Read the Label: The most common polyhydroxy acid is gluconolactone, and the most common polyhydroxy bionic acids include lactobionic acid and maltobionic acid.
How They Work: The larger molecular structures of PHAs do not penetrate the dermis as readily and, therefore, tend to be less irritating and better suited for more sensitive skin types. They have been proven to be compatible with dry, itchy skin conditions such as eczema and atopic rosacea. In addition, PHAs provide more moisturizing and more free-radical scavenging effects, making them extra impactful when it comes to anti-aging versus their AHAs relatives. Speaking of moisture, gluconolactone also acts as a humectant as it’s able to hold four-times its weight in water compared to hyaluronic acid, meaning it can hold 4,000-times its weight in water. This positions it with dual benefits – chemical exfoliant and superior hydrating agent.
Ideal Candidate: PHAs are best for sensitive skin types because the larger molecule size tends to be milder and contain additional hydrating properties.
How to Use: The larger molecule size and surface-level penetration of PHAs make them ideal for virtually all skin types — including those with rosacea, eczema, and breakouts (though BHAs are usually considered the superior acne fighter). Their mild nature means it's usually okay to pair with retinol and retinoids and use during the day or post-procedure.
The Benefits of Hydroxy Acids for Body
Whether you have a well-established facial skincare routine that contains hydroxy acids or not, Dr. Kunin says it’s important to remember that “good skincare doesn’t stop at the neck.” That’s because, in many ways, skin is skin. “Active acids are great for the face as well as the skin on our bodies as our body skin deals with the same issues as our face. The skin on our body is also prone to acne, irritation, dryness, wrinkles, and sun damage.
In fact, some may make the case that the skin below the neck needs even more TLC. It is very common for folks to go to great lengths to care for the dermis on the face but neglect the dermis elsewhere on the body. While our face is what we present first to the world, the dermis covers the entire body and requires just as much — and arguably more — care than the face. Why? Our body is frequently exposed to environmental elements and pollutants, clothing dyes and chemicals, and washed with harsh soaps and sanitizers. The body is often neglected when it comes to regular exfoliation and, therefore, is left with a rough, uneven texture. Furthermore, a lack of proper sun protection leads to unnecessary wrinkling and discoloration.
For all of these reasons, hydroxy acids can prove beneficial. Utilizing body washes and body care that have AHAs, PHAs, and BHAs can promote anti-aging benefits where we need them most. While products formulated for the face are usually the gateway, people become comfortable using body washes, body toners, and body moisturizers with these multi-correctional acids.
When choosing which hydroxy acids to include in your skincare or body care routine, the main thing to take into account are your overall skincare goals:
For Dullness: AHAs, PHAs
For Sun Damage: AHAs, BHAs, PHAs
For Acne & Clogged Pores: BHAs
For Rough, Bumpy Skin: AHAs, BHAs, PHAs
For Added Moisture: AHAs, PHAs
Those with dry, crepey, and sun-damaged skin and those with blemishes on their body would benefit most from adding a body product with AHAs, BHAs and/or PHAs, as these acids exfoliate, decrease inflammation, and stimulate collagen renewal. This is especially important because the skin on our bodies has a slower turnover rate than the skin on our face. This is why it might feel like it takes forever for post-acne marks to fade. Using body products that contain active acids stimulates the skin on our body to replace older cells with newer healthier cells, which, in turn, help to brighten and correct skin imperfections.
In case you need further convincing, physical exfoliants simply can’t compare to their chemical counterparts. Research has made it clear: The best body exfoliant comes in the form of a leave-on AHA or BHA exfoliant. When well-formulated, these exfoliants gently dissolve the bonds holding dead skin to the surface, revealing the fresh, healthy-looking, bump-free skin beneath.
How to Start Using Hydroxy Acids
Ready to start incorporating AHAs, BHAs, and/or PHAs into your body care regimen? Here’s what you need to know. Anyone who lacks a dermatological condition that is hypersensitive (think: rosacea or atopic dermatitis) is a great candidate for body products containing these acids — as long as they are regularly used. If you have sensitive skin, you may want to start with a PHAs or BHAs, as the molecular size of these acids is larger and less irritating. AHAs are the most likely to cause stinging and irritation in sensitive skin types because the small molecular size allows them to penetrate the skin quickly.
If you are wondering what types of products to look for body washes and body care with these acids will help to exfoliate and clear dead surface skin cells in the stratum corneum and thus enhance the appearance of fine lines and wrinkles. But that’s not all. Acids can support our skin barrier by increasing ceramide activity, help to remodel the dermal matrix of our skin barrier by stimulating collagen fibers and improving the quality of elastic fibers… [and] promote a reduction in hyperpigmentation, wrinkles, and crepe-like textures.
If you are dealing with uneven skin texture concerns, hydroxy acid-infused body care is good for anyone experiencing keratosis pilaris (KP), bikini bumps, ingrown hair, crepey skin, backne, and more. For skin from the neck down that is prone to clogged pores, blemishes, redness, or is rough and bumpy, applying a BHA body exfoliant that contains 2% salicylic acid once or twice a day is best.
As with any skincare, sustained use is required to see and maintain the results. Two plus weeks of consistent use is necessary to see the benefits of hydroxy acids. The patience does pay off though. The benefits noted in the studies include reduced hyperpigmentation and wrinkling, increased firmness, and improved texture and smoothness.
Elle 2001; Aedit 2022