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The Benefits of Alpha Hydroxy Acids

Posted Mar 02 2009 1:48am
AHA's are probably one of the most versatile and multi-purpose ingredients when it comes to skin care. They can be useful to both oily/acneic skin types and the "mature" skin group. This is a rare combination!

AHA's increase exfoliation by loosening the "glue" that holds skin cells together. In doing so dead skin cells are removed,  oil is controlled, the look of fine lines is reduced, skin coloring is improved and the tone is evened out. All glowy and smooth.

Sounds win/win to me. So why are some more effective or popular than others? Are there side effects? Why do they work?

Why the other AHA's are jealous of Glycolic.

You know when you see a ridiculously beautiful person and wonder why they won the genetic lottery? Well, Glycolic Acid is the pretty, intelligent, talented sister of the AHA's. It has a smaller molecular structure and goes further into the skin. Because it penetrates so well, the exfoliation is more complete. For more on Glycolic Acid, please see the blog post.

Overview of the overlooked AHA's.

Lactic: We've all heard the "Cleopatra bathing in milk" story. There is a reason. Lactic acid usually comes from soured dairy products and is gentler than Glycolic. With the larger molecules they don't absorb as deep, therefore cause less irritation, it's wonderful for more sensitive skins. Exfoliating, softening, moisturizing and humectant-y (holds water in the uppers layers of the epidermis=firm and plump!) lactic is definitely not to be ignored.

Malic: The sour acid. Found in unripe fruit, tart foods and especially apples, Malic is a gentle exfoliant that is smoothing. It does have anti-oxidant properties, but those are mostly from ingesting the foods it's found in. Like sour keys. Kidding. There's no research to indicate that it's topically beneficial in slowing the aging process, but it does provide a little more exfoliation when included in products. It's molecules are twice the size of glycolic acid so it doesn't go anywhere as deep.

Tartaric: Oh Tartaric. You try, you really do. This is a by-product from the grapes used to make wines. It has very minimal benefits, but enough that during the middle ages wine was used as a skin treatment by hip, castle-dwelling ladies to get glowing skin.

Citric Acid: Completely deserving of its own post, we'll touch on this quickly.  Vitamin C  can be extremely unstable in liquid or lotion products. When exposed to air or sunlight it oxidizes very quickly and actually causes free radical damage once that happens. Stabilized vitamin C is available but is very expensive so will come with a higher price tag accordingly. In those siuations it does wonders for stimulating collagen growth and brightening the skin beautifully. Vitamin C derivatives (Ascorbyl Plamitate and Magnesium Ascorbyl  Phosphate) are more stable and less irritating but may may not be AS effective. More research is needed!

Either way, beware cheap products that claim Vitamin C as an ingredient, they won't work because as an effective ingredient it is pricey, no getting around that. Packaging usually needs to be opaque and in an airtight pump.

Are they safe?

What makes this interesting is that because of how deep Glycolic Acid can go it almost takes AHA's into the realm of being categorized as a drug. Almost. The Cosmetic Ingredients Review Report last looked into them in 1998 and the FDA should hopefully be doing a review again soon. As a result the percentages and pH are strictly implemented to protect the consumer.

  • For home use 10% or below and a pH of 3.5 or higher
  • Cosmotologists can use 20-30% with a pH of no less than 3
  • Dermatologists and doctors can use  50-70%, but this results in severe peeling and redness, some oozing...usually with a recovery time of a week or two.

What terrifies me while writing this is the amount of high percentage glycolics available on online auction sites for anyone with absolutely no training. Shudder.

So use only the suggested percentages for home use! When that's done, you get all the beautiful  advantages of AHA's and no face melting.

AHA's are water soluble and less irritating to the skin than benzoyl peroxide, which makes them great for acneic skin. If you can find an AHA product that has salicylic in it, even better! Because it's fat-soluble, it can dissolve the oil that clogs pores, lifting out the bacteria and exfoliating away the clumped skin cells.

There can still be side effects of redness, tingling and some itching though. A small amount is ok, but if it becomes unbearable, just rinse away with water.

Tips for types of AHA products.

  • It can cause photo sensitivity, try and use the fewest amount of AHA products in your regime as possible and always wear sunscreen. Always. Go put some on right now.
  • AHA cleansers don't really make a lot of sense unless you spend at least two minutes washing your face. The AHA needs to be absorbed and that takes time. Applying and then rinsing does keep your sink drain exfoliated and young looking though.


AHA's are wonderful. There is one out there for everyone if it's used properly and instructions are followed. They really do improve the look of skin, people just need to be  careful! Thank you to @ ahalchemist for some great info on AHA's. Because information hasn't been updated in a decade it can be difficult to find relevant studies.

If you have any questions regarding which AHA products would be good for you, please don't hesitate to contact us at or at 1.877.224.4315.

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