Glycolic acid and lactic acid: digging deeper

Glycolic acid and lactic acid: digging deeper

To be honest, I’m not sure how many of my readers actually want to know this but I find this quite fascinating and these ingredients are big when you go for facials.

I’ve spoken about hydroxy acids as a whole – go read it before this, it may help you follow. Now I’m going to focus on glycolic and lactic acids.

Sometimes AHAs (Alpha-hydroxy acids) are called fruit acids but in reality the two most popular ones are not what pops into mind when you think of fruit. Glycolic acid can be found in some fruits, but its found in abundance in sugar cane. Lactic acid is mostly found in fermented fruit and most recognisably in sour milk or sore muscles. All of this is irrelevant actually, since what they use in skincare is all synthetically made – not toxic, read here to see why. Everyone relax. Sorry for wasting 10 seconds of your time, moving on.


Cell renewal

Lets get down to the science. As mentioned in my previous post, AHAs are chemical exfoliants which help get rid of the dead cells on the upper surface of the skin. So a whole bunch of AHAs were tested and compared and its found that glycolic and lactic acids are the top performers (others included citric acid and malic acid). This is based on the rate and effectiveness of cell renewal versus skin irritation.

Funny sidenote – they tested the irritation potential on the nasal folds of the test subjects. I find it funny picturing people having their nasal folds prodded and rubbed by a swarm of scientists in lab coats.

Long-term effects of lactic acid is basically the same as glycolic acid but seems to cause less irritation – the L enantiomer/form of it. It’s thought that because the lactic acid is slightly bigger it doesn’t penetrate as quickly or perhaps even as deeply.

Collagen production

Lets talk collagen! There have been a few studies showing that collagen production increases with the use of glycolic acid. Collagen is the stuff that makes your skin have elasticity and bounce back after you’ve frowned the whole day at your clients/colleagues/mom/kids/husband/boyfriend/dramatic friend. I couldn’t really find the same sort of studies for lactic acid. I looked for about 10 minutes – so pretty deep research happening here. The studies tend to be about food science like this one: Use of lactic acid for extraction of fish skin gelatin. Eww, gross.


Now you wouldn’t think of acids as being pretty hydrating but these little guys, glycolic and lactic acid, are hygroscopic and act as humectants. Loosely translated: They like to attract water and hold onto them; they’re a bit clingy, shem. This means that once the ingredient is busy working its magic in all the ways above, it’s also preventing the product and your skin from dehydrating.


The strength or effectiveness of these acids are dependent on:

  1. Concentration
  2. pH
  3. Duration of contact with skin

So these two compounds are used in chemical peels and in low concentrations in some masks, cleansers, toners and even some moisturisers.

Ok! next*clap* acid*clap*. (if you don’t get this joke – its Pewdiepie… please keep up gah).


  1. Hydroxy Acids and Retanoids in Cosmetics – Ramos-Silca et al. in Clinics in Dermatology
  2. Comparative effectiveness of a-hydroxy acids on skin properties – Smith in International Journal of Cosmetic Science
  3. Collagen studies – glycolic acid:
    1. Glycolic Acid Treatment Increases Type I Collagen mRNA and Hyaluronic Acid Content of Human Skin – Bernstein et al. in Dermatological Surgery (only 15 test subjects)
    2. Glycolic Acid Modulation of Collagen Production in Human Skin Fibroblast Cultures In Vitro – Moy et al. in Dermatological Surgery (cell cultures)
    3. The Effect of Glycolic Acid on Cultured Human Skin Fibroblasts: Cell Proliferative Effect and Increased Collagen Synthesis – Kim et al. in The Journal of Dermatology (cell cultures)
  4. PubChem: Glycolic acid and Lactic acid

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