What Scientists Know About Alpha-Hydroxy Acids – Women’s Concepts
With a close glance at most of the skincare products on your vanity countertop, you can see one or more of the alpha-hydroxy acids (AHAs) family. As true multitaskers that benefit the skin like no other ingredient can, AHAs are added to all kinds of formulations, from cleansers to serums, moisturizers, and peels. Despite their reputation for being harsh to some, AHAs share benefits for all skin types — sensitive included — if used correctly. In this post, we’re breaking down everything about alpha-hydroxy acids and how to use them to get the best results without reactions and everything in between.
What are AHAs?
Alpha-hydroxy acids are naturally occurring acid compounds derived from various fruits, sugar cane, or milk. In skincare, AHAs are used to dissolve the “glue” that holds dead cells on the skin’s surface, revealing healthier cells, hence smoother and evener skin. Also, once buildup is removed from the surface, the skin appears more luminous and radiant as it better reflects the light, plus the products you apply get deeper absorbed, so more perks. Depending on their molecular weight, AHAs work either in the deeper layers or on top of the skin, the formers being more potent and the latter gentler.
A lesser known fact is that AHAs are humectants, meaning they attract water into the skin, increasing hydration levels, plumping wrinkles, and balancing oil.[1]
What are the most common AHAs used in skincare?
The most common AHAs used in skincare include glycolic acid (derived from sugar cane), lactic acid (from milk), malic acid (from apples), and citric acid (from lemons). Among these, glycolic and lactic acids enjoy the most considerable fame and for fair reasons.
Glycolic acid is the most potent acid from the AHAs family, praised for its exfoliating abilities and capacity to go beneath the skin’s surface due to its small molecular size. Once it penetrates the skin, glycolic acid triggers collagen production, so it accelerates wound healing and reduces aging signs.[2] Besides, glycolic acid has antibacterial and anti-inflammatory benefits, making it useful for breakout-prone skin too. Some studies also support the hypothesis that glycolic acid has antioxidant activity.[3]
Another famous AHA family member is lactic acid, the gentle one. Due to its larger molecule, lactic acid acts more on the top of the skin, where it speeds up cell turnover. As a result, skin becomes smoother and evener, the texture is refined, and fine lines and wrinkles appear less visible. Lactic acid is also a go-to for acne sufferers as it decreases inflamed pimples while working as a preventative measure against breakouts.[4] Lastly, lactic acid was found to improve skin firmness when used in concentrations of 12% twice a day.[5]
Who should use AHAs?
Everyone can use AHAs as long as they don’t experience redness, excessive dryness, or irritation. However, if you’re a newbie in using acids, you want to start with lactic acid because it’s milder and then go for the more potent one, glycolic acid. And if your skin is easily reactive, you should start with a low-concentrated product and slowly work up to more potent formulas as tolerated. For instance, if your skin is problematic, you can use a glycolic acid toner or moisturizer to help your skin adjust to it, then go for more potent formulas, like serums and peels.
Most often, alpha-hydroxy acids are used for age-related concerns, including fine lines, wrinkles, and dark spots. And despite the popular belief, AHAs are great for dry skin, too, especially lactic acid as it’s gentler. In the case of blackheads and pimples, a BHA product works better because it’s oil soluble and can penetrate deeper into the pores to unclog them. On the other hand, AHAs are water-soluble, so they don’t sink as deep into the skin, which is why experts recommend them for normal, combination, dry and aging skin.
Are AHAs safe for skin?
According to the CIR Expert Panel, glycolic and lactic acids are safe for use in cosmetic products at concentrations of a maximum of 10% and pH no higher than 3.5.[6] In rare cases, using alpha hydroxy acid can have side effects such as redness, itching, redness, and irritation. Also, AHAs make the skin sensitive to sunlight, so it’s crucial to use sunscreen while using products with alpha-hydroxy acids.
How to use AHAs
AHAs are most potent when used in serums and peels. As such, if you’re using a glycolic acid serum (or a serum with lactic acid), apply it on cleansed skin and before moisturizer and sunscreen. It’s important that the type of moisturizer you follow up with contains occlusives, especially if the humidity in your area is lower than 70%. Otherwise, the acids draw water from the inner layers of the skin, allowing its evaporation. Consequently, using an occlusive moisturizer after AHA serums decreases the chances of dehydration.
In the case of chemical peels, they are best when used at PM as they can increase skin’s sensitivity to sunlight. On cleansed, dry skin, layer your AHA-infused peel and leave it to act for 10 minutes. Rinse it off and follow up with your repairing moisturizer.
Frequently asked questions about AHAs
- Can you use AHAs with retinol?
It’s fine to use AHAs with retinol, either on alternative days or use acids in the morning and retinol in your nighttime routine.
- Can you use AHAs with vitamin C?
Because AHAs and vitamin C are formulated at an acidic pH, you should use them at different times (vitamin C in the morning, AHAs at night) or on alternative days.
- Can you use AHAs with BHAs?
It’s safe to use AHAs and BHAs together as long as you don’t have problematic skin. They team up well to work on the skin’s surface and beneath to remove the buildup of dead cells and unclog pores.
- Can you use AHAs on sensitive skin?
It’s ok to use AHAs on sensitive skin if the product has a low concentration of acids. You can gradually work up to stronger formulas as your skin builds tolerance.
- Can you use AHAs on acne-prone skin?
AHAs are excellent for acne-prone skin due to their anti-inflammatory and exfoliating properties. They are good at cleansing pores, which is where dead cells and bacteria accumulate, the ones that make pimples arise.
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- Purnamawati S, Indrastuti N, Danarti R, Saefudin T. The Role of Moisturizers in Addressing Various Kinds of Dermatitis: A Review. Clin Med Res. 2017 Dec, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5849435/
- Kim SJ, Park JH, Kim DH, Won YH, Maibach HI. Increased in vivo collagen synthesis and in vitro cell proliferative effect of glycolic acid. Dermatol Surg. 1998 Oct;24, https://pubmed.ncbi.nlm.nih.gov/9793513/
- Perricone NV, DiNardo JC. Photoprotective and antiinflammatory effects of topical glycolic acid. Dermatol Surg. 1996 May;22, https://pubmed.ncbi.nlm.nih.gov/8634805/
- Garg T, Ramam M, Pasricha JS, Verma KK. Long term topical application of lactic acid/lactate lotion as a preventive treatment for acne vulgaris. Indian J Dermatol Venereol Leprol. 2002 May-Jun, https://pubmed.ncbi.nlm.nih.gov/17656910/
- Walter P Smith, Epidermal and dermal effects of topical lactic acid, Journal of the American Academy of Dermatology, Volume 35, Issue 3, Part 1, 1996, Pages 388-391, https://www.sciencedirect.com/science/article/abs/pii/S0190962296906027
- The U.S. Food & Drug Administration, Guidance for Industry: Labeling for Cosmetics Containing Alpha Hydroxy Acids