AHA's vs BHA's. What is the difference?

If you’re interested in skincare, chances are you have heard of, or even used AHAs. But have you heard of their less well-known relatives BHA’s? Understanding what these two ingredients are, their differences and their unique benefits is essential for any skincare junkie. In this article we are going to break down the A’s + B’s of this gold-standard dermatological ingredient.

Firstly it is important to understand that both AHA’s (alpha hydroxy acid) and BHAs (beta hydroxy acid) are acids that are naturally occurring in certain fruits and other biological substances. These acids can also be synthetically altered in the laboratory to extend them further and it is more often than not this form that is used in skincare.

What are AHAs?

AHAs have been used in cosmetics and skincare for over 40 years in many forms from at-home creams & serums to clinical peels performed under the expertise of a dermatologist. AHAs are organic acids that are named according to their biochemical structure (one hydroxyl group attached to the alpha position of the acid for those chem nerds out there!)

The most common AHAs found in skincare formulations & their origin include:

Glycolic acid (sugar cane)
Lactic acid (fermented milk or fruit products)
Malic acid (apples)
Tartaric acid (fermented grapes, Davidson Plum)
Citric acid (citrus fruits)
Ascorbic acid (fruits including native australian Kakadu Plum, Finger Lime, Davidson Plum)

AHAs work by stimulating exfoliation of the most superficial layers of the skin - the epidermis & stratum corneum. This action sloughs away dull and rough skin and stimulates the renewal and production of fresh & healthy cells in the deeper layers of the skin resulting in softer, smoother skin, reduction in fine lines & wrinkles, improved pigmentation, and decreased acne. AHAs can also improve the skin’s barrier function, reducing skin sensitivity and leading to a more youthful appearance by improving skin firmness, hydration & clarity. Want to know more about AHAs? Read the article: The benefits of AHAs.

What are BHA’s?

The primary difference between AHAs and BHAs is that alpha’s are water soluble acids and beta’s are fat-soluble. And yes, for those chem nerds out there the structure differs in that BHA has one hydroxyl group attached to the beta position of the acid.

Ultimately what this means is that BHAs work differently on the skin than AHAs as they are able to penetrate the sebaceous (oil) glands in the skin, making them ideal for those with oily skin, acne, bumpy & congested skin and conditions like keratosis pilaris. BHAs also have an anti-inflammatory effect on the skin, making them suitable for sensitive & sensitised skin.

The most common BHA found in skincare formulations is:

-Salicylic acid (Willow Tree Bark, Wintergreen Leaves)

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