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Alpha Hydroxy Acid Skincare: The Facts about AHA

Alpha Hydroxy Acid (AHA) is an incredibly popular active skincare ingredient.

But for a skincare ingredient that has been around for such a long time, there are still misunderstandings about what AHA does for the skin.

Have you asked “Is Alpha Hydroxy Acid safe?”
Or “Is Alpha Hydroxy Acid good for the skin?”

Well, the answer to some of these questions is:

It depends.

Alpha Hydroxy Acid and Skincare

berries in a bowl

Alpha Hydroxy Acid is a relatively weak acid with valuable anti-aging effects.[1]

It’s effective for treating[1][2]:

  • Acne
  • Hyperpigmentation
  • Dark Spots
  • Wrinkles

  • Sun aged skin
  • Pockmarks
  • Warts
  • Acne scars

The term Alpha Hydroxy Acid is actually used to describe a group of acids.
Specifically, Carboxylic Acids with a Hydroxy group attached to the alpha carbon.

The Ordinary AHA 30% + BHA 2% Peeling Solution Bottle


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Common Alpha Hydroxy Acids used in skincare products are[1][2]:

  • Glycolic Acid – Simplest AHA and a natural source is sugarcanes.
  • Lactic Acid – Naturally occurring in sour milk.
  • Malic Acid – Common in fruits.
  • Citric Acid – Also naturally found in fruits. (Not to be confused with Vitamin-C, which is Ascorbic Acid.)

Some skincare products have AHA on the label.
But, the ingredients list will specify one or more of these acids.

Glycolic Acid is the actual AHA molecule typically used in skincare products.
Having a small molecular size allows it to be effective by absorbing deep into the skin.[2]

Olehenriksen Glow2OH Dark Spot Toner Label
Olehenriksen Glow2OH Dark Spot Toner w/ potent AHA’s

It’s worth noting a few things that’s often brought up when discussing AHA’s:

  1. Beta Hydroxy Acid (BHA) and Poly Hydroxy Acid (PHA), the other Hydroxy Acids in skincare.
    • The difference between AHA and BHA?
      BHA molecules have a Hydroxy group on the next carbon over, in the beta position!
      Ex: Salicylic Acid is a common BHA used in skincare.
    • Some AHA’s are also BHA’s.
      Ex: Malic Acid and Citric Acid.[2]
    • PHA’s have more than one Hydroxy groups, making the overall structure bigger.
      Studies show PHA’s have similar effects as AHA’s, but cause less skin irritation.[5]
  2. Is Alpha Hydroxy Acid the same as Hyaluronic Acid?
    • Hyaluronic Acid is not an AHA simply because there is no hydroxy acid in the alpha position.
Olehenriksen Glow2OH Dark Spot Toner and Cotton Pads


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Why is Alpha Hydroxy Acid popular for skincare?

Many skincare products use weak acids to repair and make skin healthy.
Your skincare routine might already include weak acids like Hyaluronic Acid or Ascorbic Acid (Vitamin C).

Alpha Hydroxy Acid works by promoting new skin growth!
Generally, AHA achieves this by:

  1. Irritating the outermost layer of skin cells.[1]
  2. Exfoliating the outer layer of skin.[3]
  3. Producing new skin cells, replacing older skin.
  4. Stimulating the production of supporting molecules like Hyaluronic Acid and Collagen[1][4], strengthening the skin barrier.

Skin treated with AHA appears tighter and has less wrinkles because of the renewed skin barrier.

In most cases, there are two ways to use AHA and the differences are dramatic!

SK-II GenOptics Aura Essence Bottle Closeup of Brand Name


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Alpha Hydroxy Acid Concentration!

When adding new products to a skincare routine, take a moment to think about your skincare goals are and how you want to achieve it, especially when using AHA.

AHA has two main groups used in skincare.

Low Concentration AHA (4-10%)[2]

  • Affects the outermost layers of skin.[1]
  • Can be used in daily skincare routine.
  • Common active ingredient in toners, moisturizers and creams.
  • Changes occur much slowly, usually taking months.
  • Makes the skin slightly sensitive to the sun.

High Concentration AHA (20%+)[2]

  • Penetrates and alters all the layers of the skin.[1]
  • Used in chemical peel procedures.
  • May cause burning & irritation during the procedure.
  • Outer layer of skin starts to peel and flake dramatically within days.[3]
  • While skin is peeling, exposed skin is super sensitive to the sun.

Remarkably, AHA’s produces visible results and isn’t hyped up marketing.

The following benefits were observed by scientists:[1]

  • AHA increased new skin renewal rate.
  • Collagen regeneration improved with the use of AHA.
  • The outer layer of skin thickened to treat damaged skin.

In addition, another set of tests found that Alpha Hydroxy Acids actually lowered the melanin count, resulting in new, less pigmented and lighter skin.[2]

dab of lotion on hand

Finally, another study confirmed that repairing skin damage was possible by using Alpha Hydroxy Acid with other skincare ingredients like Vitamin C, Vitamin E and Niacinamide.[4]

Alpha Hydroxy Acid in your skincare routine.

Used properly, AHA can drastically improve skin appearance and health.
However, weak acids are still minor irritants to the skin.

Most common side-effects[1][4] of using AHA’s are:

  • Swelling
  • Sensitivity to UV light
  • Irritation

  • Burning Sensation
  • Redness
  • Dryness

Because AHA stimulates the outermost layer of skin to shed, sensitive layers of skin underneath are exposed to the Sun’s harsh UV rays.[1][2][4]

Patients treated with [Glycolic Acid] (20–50%) every other day for the removal of the keratin layer experienced serious UV damage.

Tang & Yang, 2018
hand reaching towards sunlight

Sunlight even caused “uneven skin pigmentation”[1] to exposed skin using low concentration AHA.

To prevent skin damage, experts advised:

broad spectrum SPF of 30+ as sun protection is essential when using a product containing AHAs as these ingredients increase the skin’s sensitivity to UV light.

Tran, Townley, Barnes & Greive, 2015
woman wearing black sweater


Want to add AHA’s to your skincare routine?
Don’t forget the sunscreen!

Attainable skincare goals using AHA

There are many ways to use Alpha Hydroxy Acid to achieve your skincare goals.
Just be aware that sunlight and AHA does not mix!

FDA lists AHA (specifically Malic Acid and Citric Acid) as safe for food and for use in skincare.[1]

Pro-tip: We suggest including AHA skincare products as part of your night-time PM skincare routine!

However, don’t forget to thoroughly wash and apply sunblock whenever using AHA products.
Even when it’s cloudy outside, sunblock is a MUST!

Did you know that you can get sunburned even on cloudy days?
Click here to read more!

Here’s a bit of fun trivia:

In ancient times, Cleopatra was said to bathe in sour milk, which contains lactic acid, in order to give her skin a youthful appearance.

Tran, Townley, Barnes & Greive, 2015
Two women working in laboratory


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  1. Tang, S., Yang, J. (2018). Dual Effects of Alpha-Hydroxy Acids on the Skin.
  2. Kornhauser, A., Coelho, S., Hearing, V. (2010). Special emphasis is devoted to the safety evaluation of these formulations, in particular on the effects of their prolonged use on sun-exposed skin.
  3. Moghimipour, E. (2012). Hydroxy Acids, the Most Widely Used Anti-aging Agents.
  4. Tran, D., Townley, J., Barnes, T., Greive, K. (2015). An antiaging skin care system containing alpha hydroxy acids and vitamins improves the biomechanical parameters of facial skin.
  5. Grimes, P., Green, B., Wildnauer, R., Edison, B. (2004). The Use of Polyhydroxy Acids (PHAS) in Photoaged Skin.