Exfoliate Gently with these 8 Essential Acids

by Teresa Fu, M.D.

When it comes to skincare, you might think applying acids to your skin sounds scary rather than healthy. But acids are essential ingredients that have anti-inflammatory and exfoliative properties, and when used properly, can help reduce dark spots, even out skin tone, and provide a brightening effect. They are also often used to fight acne. In this post we’ll go over the most essential acids to look for when considering skincare products. We’ll cover the most common acids as well as ones that you might not have heard as much about, such as gluconolactone, and when to consider incorporating these amazing ingredients into your skincare routine.

Types of Acids

There are several main classes of acids: alpha-hydroxy acids (AHA), and beta-hydroxy acids (BHA). The names reflect the way the molecular structures are arranged, which in turn affects how they affect and interact with the different layers of skin. AHAs mainly work as superficial exfoliators, sweeping away dead cells on the surface to reveal the healthy new skin underneath. This process can smooth out fine lines and result in a brighter complexion. AHAs may also stimulate a bit of collagen production in the process. BHAs work deeper in the skin and sink into the pores, getting down to the level of the oil glands. These are commonly used in acne products. Polyhydroxy acids (PHAs) are chemical cousins of AHAs - technically, they are second-generation versions - that are coming into wider use. Considered a gentler type of exfoliant, PHAs are larger than AHAs and BHAs, so they work on the surface of the skin without disrupting the underlying layers, meaning they are less irritating. Like AHAs, they also help even out the tone and texture of skin by gently removing the superficial dead skin cells, and are great moisturizing ingredients as well by drawing water to the skin.

Now let’s talk about the top 8 acids to add to your routine!

Glycolic Acid

This sugar-derived alpha-hydroxy acid is super common these days in skincare. It’s a small molecule, so it can penetrate deeper into the skin. Glycolic acid works by sweeping away dead skin and pore-clogging debris, resulting in smoother skin. It can also help lighten dark spots and stimulate collagen production and some studies show it might even reverse signs of UV-damage in cells It is used in anti-aging products as well as acne treatments. The downside is that it may be irritating with overuse, so we recommend looking for a product with a lower concentration or using it a couple times a week for all the benefits and none of the drawbacks.

Lactic Acid

Ever hear of Cleopatra taking baths in milk for silky smooth skin? That smoothing action was courtesy of the lactic acid found in milk. Lactic Acid is an AHA that is slightly larger in size than glycolic acid. This sugar-derived acid is gentler but still effective, making it useful for those with more sensitive skin. Lactic acid can be found in serums for anti-aging at lower concentrations, providing a gentle exfoliative effect and stimulating cell renewal. It is also useful as an ingredient in lotions used for rough, dry skin on areas like the elbows, lower legs, and feet and has been shown to increase ceramide production in the skin.

Ferulic Acid

Ferulic acid is a wonderful antioxidant ingredient, used primarily to boost effectiveness of ingredients like vitamins C, E, and A in skincare. Think of it as a trusty side-kick with its own free-radical-fighting properties. In skincare, it is often found alongside vitamin C to stabilize this notoriously unstable ingredient. Some studies even suggest ferulic acid can double vitamin C’s sun protective qualities.

Salicylic Acid

This well-known beta-hydroxy acid is used in everything from acne spot treatments to masks for the face (and even feet!) It’s a powerhouse acid derived from plants (willow bark) that breaks down oil, unclogging pores, and sweeping away dead skin. Products containing salicylic acid in lower concentrations are generally well-tolerated, and also safe for pregnancy and when nursing. Note that higher concentrations may cause mild irritation so if you have more sensitive skin, start slow and always patch test.

Hyaluronic Acid

Technically an acid by its chemical properties, HA is a powerhouse moisturizer and is used in many forms in skincare. It’s an essential component of the support structure of connective tissues that include the skin, eyes, and joints. As a cosmeceutical ingredient, it is a humectant, meaning that it attracts water and binds those water molecules to the skin - it can absorb up to 1,000 times its own weight! Products containing HA work by holding moisture on the skin, resulting in plumper, dewy skin.

Gluconolactone

This second-generation AHA, part of a group called PHAs, is good for all skin types, especially those with sensitive skin who can’t tolerate standard AHAs or BHAs. It’s suitable for daily use. With its extra hydroxyl groups (remember high school chemistry?) it’s a larger molecule that stays on the upper layers of skin, and also draws extra water to the skin, making it a gentle, effective ingredient for exfoliation and hydration. There’s some evidence it also has antioxidant and anti microbial properties as well, which make it useful in anti-aging and anti-acne products.

Lactobionic Acid

Another form of PHA, this ingredient is derived from milk, like lactic acid, and works well as an exfoliant for the upper layers of skin without the irritation that AHAs can cause. Like gluconolactone, it also exhibits antioxidant properties, making it useful as an adjunct ingredient in daily anti-aging treatments.

Azelaic Acid

Neither an AHA or BHA, azelaic acid is saturated dicarboxylic acid found naturally in grains such as wheat, barley, and rye. It’s also produced naturally on the skin. It is a super useful ingredient with anti-inflammatory and antioxidant properties, with additional antibacterial and brightening properties, and is used for a wide range of skin conditions including acne, rosacea, and melasma. As a bonus, it’s one of the pregnancy-safe medications often prescribed for acne.

How to Use Acids

In any skincare routine, you should consider incorporating gentle exfoliation at least a couple times a week, and by choosing ingredients carefully, even the most sensitive skin can benefit.

For acne-prone skin: those with mild acne might first reach for a salicylic acid cleanser as a good first step to fight oil production and unclog pores. This can be especially helpful for those with acne on the chest and back that is worsened with sweating. For more severe acne, this might not be enough and you’ll definitely want to visit your dermatologist for more targeted options.

For anti-aging purposes, a once or twice weekly clean-sweep using a gentle but effective serum can help provide a healthy exfoliative effect without excess irritation.

For general moisturizing, a lotion with salicylic or lactic acid can be helpful for smoothing out rough skin anywhere on the body although some people might find these lotions too irritating for the face.

Those with normal to oilier skin can also look into peels, whether over the counter, in a salon, or in a dermatologist’s clinic. Using higher concentrations of acids, peels can provide a deeper exfoliative experience and work faster at fading dark spots and treating fine lines.

At home peels: These can be a fun way to incorporate acids into your routine as a bit of self-pampering and can help provide a brightening pick-me-up. As with any new product, a judicious approach is best! Make sure you go with a reliable product and brand, and start with a lower strength if you are new to these. Test a new product on your inner arm for a day or two to make sure you aren’t going to have a vigorous reaction. If you’re good to go, you can proceed to using it on the face. Make sure you cleanse the skin first and dry it well. Then follow the directions on the product packaging including rinsing off if indicated, and pampering your skin after the peel by applying a good moisturizer and using sunscreen regularly afterwards. Any burning or pain is a red flag - make sure you rinse off immediately.

If you opt for a more professional approach, many salons or aesthetician offices may also offer peels in varying strengths. An aesthetician you trust is a valuable part of your skincare team. Finally, peels may be offered at a dermatologist’s office. These range in strength: from superficial -with brightening effect with little to no downtime, medium - more intense with some downtime, and deep - most aggressive, and most effective with significant downtime. If you are still confused, have a conversation with your dermatologist about the best options for you.

Looking for an all-purpose super gentle acid exfoliant? The Emdash Clear Reveal Resurfacing Serum contains AHAs, BHAs, and PHAs and is gentle enough for all skin types.

Disclaimer: As with all our posts, this blog is meant to be for informational and educational purposes, and is not medical advice. When in doubt, please ask your physician.

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Teresa Fu, M.D.

Dr. Teresa Fu is a board certified dermatologist and mother of two. She graduated from Stanford Medical School and practices in the San Francisco Bay Area.