Alpha Hydroxy Acid (AHA): A Great Way to Exfoliate Skin
by elmt Lab on Apr 07, 2023
elmt Lab here again to introduce yet another superhero ingredient for skin - this time, one that can unlock the secret to smoother, younger-looking skin.
Alpha Hydroxy Acids (AHA) have become increasingly popular for gently exfoliating skin, removing dead skin cells and promoting a radiant complexion. While dermatological peeling procedures use high concentrations of these water-soluble acids (20-70%) for optimum results, lower concentrations are safe for everyday use and suitable for most skin types .
Read more to learn about AHAs full range of benefits, what type is right for you, and how to incorporate it into your skincare routine.
How it works
Alpha Hydroxy Acids (AHA) are a group of acids that occur naturally in fruits and milk, and help to exfoliate and remove dead cells from the skin's outer layer. This results in improved skin texture and tone. This process of exfoliating is essential as it not only helps improve skin appearance, but also helps other active ingredients penetrate the skin better.
AHA is safe for most skin types if used correctly, and because it also functions to moisturize and promote skin cell turnover, it is effective even for dry, sun-damaged, and/ or aging skin.
Sub-efficacy 1: Moisturizing
AHA increases the absorption rate of other moisturizing skincare products and stimulates the production of the skin's natural moisturizing factor (NMF) to maintain moisture. Glycolic acid, a representative AHA, has been found to increase hyaluronic acid and collagen levels in the skin .
Sub-efficacy 2: Cell turnover
AHA promotes the production of new and healthy skin cells, which slows down with age and therefore leads to signs of aging such as dullness and wrinkles. By helping to exfoliate and promote production of collagen and elastin, AHA is essential for maintaining skin elasticity.
Types of AHA
There are many types of AHA, and each has a slightly different characteristic, so it is important to choose the AHA that suits you. Here are three of the most commonly used AHAs in skincare.
Glycolic Acid: This acid is derived from sugarcane and is the most commonly used form of AHA. Long-term research has proven it to be safe and effective, making it a reliable option for skincare. Because of its small molecular weight, it can penetrate deep into the skin for fast results.
Lactic Acid: This acid is derived from fermented milk and has a larger molecular weight than glycolic acid. As a result, it is less irritating on the skin as it penetrates to a more shallow level, and also provides extra moisture to the skin. However, lactic acid’s exfoliating properties are effective at concentrations of over 5%, so it's important to check the content before use.
Mandelic Acid: This acid is derived from almonds and has the largest molecular weight of all AHAs. It is gentle on sensitive and dry skin, making it a suitable option for those just starting with acids, or looking for a more gentle option in comparison to others.
In addition to the above, citric acid, malic acid and tartaric acid are some other forms of AHA you might come across in skincare.
How to use AHAs correctly
So now that you’ve learned about the many benefits of AHA for skin, make sure to follow these tips to safely and effectively incorporate it into your skincare routine.
1. Go from high to low molecular weight, low to high concentration
If you are using AHA for the first time, see how your skin responds by starting with a product that has a higher molecular weight and low concentration. Mandelic Acid is a great option to start with due to its large molecular weight. Additionally, we recommend conducting a patch test on your wrist or neck before use.
2. Start slow and steady
Because AHA is an effective exfoliator, daily use can be excessive as dead skin cells actually help prevent moisture loss in the skin and act as a protective shield from the external environment.
As such, use AHAs in your routine less than 3 times a week, or once or twice every other day depending on the concentration and your skin's reaction. If no irritation and abnormality is detected, gradually increase the frequency and concentration of use.
3. Make sure to use sunscreen
While sunscreen is a must for all, we can’t stress enough the importance of applying sunscreen when using AHAs. Because AHAs help promote cell turnover by exfoliating away the protective dead skin cells, our skin can become temporarily sensitive to ultraviolet rays. We recommended applying sunscreen with at least a SPF of 30 every 2 hours.
4. Avoid incompatible ingredients
There are a couple ingredients that can cause skin damage or irritation when used with AHAs.
- Retinol: a representative anti-aging component that promotes cell turnover, it functions similarly as AHA which can cause excessive exfoliation, dryness and irritation. If you want to use both ingredients in your skincare routine, use them on alternating days, or limit to using one at day and one at night. Additionally, use plenty of moisturizer to prevent dryness and irritation.
- Benzoyl peroxide: mainly used to treat acne, it functions to regulate sebum secretion and kills the bacteria that causes acne. However when used with AHA, it can irritate the skin and cause dryness. If you want to use both ingredients in your skincare routine, we recommend waiting at least 30 minutes to apply your AHA product after your benzoyl peroxide product.
 Philipp Babilas, Ulrich Knie, Christoph Abels, Cosmetic and dermatologic use of alpha hydroxy acids, JDDG, Volume 10, Issue 7, Jul 2012, Pages 451-530
 E F Bernstein 1, J Lee, D B Brown, R Yu, E Van Scott, Glycolic acid treatment increases type I collagen mRNA and hyaluronic acid content of human skin, Dermatologic Surgery 27(5):p 429-433, May 2001.