The difference between AHA, BHA and PHA

These days, most of us would have used or heard of products with hydroxy acids. Glycolic, salicylic, lactic- just to jolt your memory. We can see and experience their effectiveness, but have you ever wondered what the difference is between each of them? Could you be using the wrong one? Which skin concerns do each target? This is why we’re here, to break it down! 

First things first, what is the main purpose of hydroxy acids?

Hydroxy acid is a type of chemical exfoliant. They weaken the connection (desmosomes) that holds dead cells together in the stratum corneum (protective layer of dead cells). Just like any other exfoliant, they help with the shedding of the stratum corneum to reveal a more even, younger, glowier skin. When used at a safe concentration, chemical exfoliants are gentler than physical exfoliation, and are less prone to causing damage on the skin.


Hydroxy acids can be divided into three categories: alpha hydroxy acids (AHA), beta hydroxy acids (BHA) and polyhydroxy acids (PHAs). All can either be synthetically made or naturally found in sugarcane, fruit and willow bark. All three have the main function of shedding dead cells, however each one provides a slightly different result. 


Alpha Hydroxy Acids: 

Glycolic Acid 

The good stuff: Due to its size, glycolic acid is considered to be the best performing acid. Since it’s the smallest hydroxyl acid molecule, it’s able to penetrate the skin the deepest and fastest. It can even go as far into the dermis, which has actually shown to effectively increase collagen production, thus assisting with wrinkle reduction. Glycolic acid can also be beneficial for people with dry skin as it can draw moisture and increase hyaluronic acid levels. It’s also great for acne prone skin by preventing clogged pores. 

The not so good: Out of the other AHAs, glycolic acid is the more irritating one. Sensitive skin pals, you might want to sit this one out!


Lactic Acid

The good stuff: In addition to exfoliation, lactic acid is great for hyperpigmentation, acne lesions and stimulation of ceramide production. Since it’s a larger molecule compared to glycolic acid, it doesn’t penetrate as deeply so this somewhat makes it a gentler AHA but still effective. Sensitive skin types usually prefer lactic acid because they tend to experience less inflammation and irritation after use.  

The not so good: If we had to be nitpicky then the only not-so-good is that its actions are slower. 


Mandelic Acid

The good stuff: Another one that’s suitable for sensitive skin. It has antimicrobial properties which makes it effective against acne and clogged pores.

The not so good: Unlike glycolic acid, mandelic acid is light-sensitive so it should be packaged in opaque packaging to help with its effectiveness. 


Beta Hydroxy Acids: 

Salicylic Acid 

The good stuff: It is an oil soluble hydroxy acid so not only can it effectively exfoliate the skin but it can also penetrate into the pore. This means that it has the ability to exfoliate inside the pore. Salicylic acid is the best option to reduce breakouts, including blackheads and whiteheads. It is best known for addressing blemish prone skin concerns and most effective as a leave on treatment. 

The not so good: For dry, eczema-prone, or sensitive skin, salicylic acid can be too harsh and lead to irritation.


Polyhydroxy Acids: 

The good stuff: The new gen alpha hydroxyl acids. It is becoming more and more widely known. It includes acids such as gluconolactone, galactose and lactobionic. These acids have a much larger molecule size. As a result, they act as surface level exfoliants - resurfacing and smoothing the skin. It is the most ideal chemical exfoliant for sensitive and rosacea skin types. 

The not so good stuff: Because of their size, polyhydroxy acids do take a little longer to show their results. 


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