What are Hydroxy Acids?

Hydroxy acids are organic compounds utilized in the beauty industry primarily because of their ability to increase skin-cell turnover rate.

The most common hydroxy acids found in skincare formulas are alpha and beta hydroxy acids. Alpha hydroxy acids (AHAs) and beta hydroxy acids (BHAs) are quite similar at the atomic level; the only difference being that AHAs have one carbon atom between their hydroxyl and carboxyl groups, while BHAs have two.


Alpha hydroxy acids can be synthetically produced or naturally sourced. In skincare formulas, AHAs are typically derived from natural food sources.

How do they work?
AHAs work by weakening or dissolving the cellular “glue”, encouraging dead skin cells to shed naturally and reveal a soft layer of new skin underneath. AHAs also stimulate the production of collagen and elastin, which are responsible for keeping your skin hydrated and supple.

Types of AHAs
The most common naturally occurring AHA is glycolic acid which is derived from sugar cane. It is the most effective because its molecules are small and penetrate more deeply into the skin, rendering the best results. Glycolic acid is the strongest of the AHAs used in skincare formulations and must be used with caution.

For people who have sensitive skin, lactic acid (milk derived) is a better choice because it is gentler on the skin and there is less risk of irritation.

Other types of AHAs derived from food are:
• Citric acid, from lemons
• Tartaric acid, from grapes
• Malic acid, from apples


The most common beta hydroxy acid used in skincare applications is salicylic acid. It is naturally occurring and derived from either willow bark or sweet birch.

How do they work?
The main difference between AHAs and BHAs is that BHAs are soluble in oil. BHAs exfoliate dead skin cells too; however, they are also capable of penetrating your pores to unclog them. Dead skin cells, oil, and bacteria trapped within your pores are the main cause of acne. Because salicylic acid is so effective at unclogging pores, it is often prescribed to treat acne. Salicylic acid also has antibacterial properties, and can zap acne-causing bacteria before they have the chance to multiply!

Which Hydroxy Acid Should You Choose?

AHAs are water soluble, therefore can only work on the surface of your skin. Because AHAs are water soluble, they are not effective at penetrating oily pores and therefore not recommended for people with oily/acne-prone skin. If your goal is to minimize the appearance of fine lines, smooth out your skin, improve skin tone, and restore moisture, AHAs are the right choice for you!

BHAs on the other hand, are oil soluble, meaning they not only work on the surface of your skin, but can also penetrate deep into your pores. BHAs are the perfect choice if your skin is oily and/or acne prone and you’re looking to reduce sebum production and/or treat acne.

How To Use Hydroxy Acids

  1. Start with a low concentration. It’s best to start off slow to see how much your skin can tolerate.
  2. Do a patch test. If you have sensitive skin, test a small area to see if you have any reactions to the product.
  3. Always wear sunscreen when using hydroxy acids because they increase photosensitivity.