Chemical exfoliation: AHA and BHA


What are AHAs and BHAs?

Alpha-hydroxy acids (AHAs) and Beta-hydroxy acids (BHAs) are both chemical exfoliants. A chemical exfoliant relies on different types of acids to breakdown the most superficial layer of skin, causing dead skin cells to detach and shed. One is not superior to the other, rather they are used to treat different concerns.

  • Alpha-hydroxy acids: AHAs are water-soluble and can be found in sugar, milk, citrus fruits or synthetic formulations. The most commonly used forms of AHAs are lactic acid, glycolic acid and mandelic acide.
  • Beta-Hydroxy Acids: BHAs are lipid or oil soluble. They are closely related to AHAs as they are separated in their configuration by a single carbon atom. The most used form of BHA is salicylic acid.

Why are they good for the skin?

AHA's and BHA's exfoliating remove the top layer of cells on the skin to reveal the newer, younger cells below. Products that include AHAs and BHAs work to:

  • Help brighten dull complexions.
  • Help to reduce the appearance of uneven skin tone.
  • Help to visibly diminish the signs of aging, by reducing the appearance of fine lines and wrinkles.
  • Promote a more radiant look.

Which one to choose?

  • AHA

The most used AHAs are lactic acid, glycolic acid and mandelic acid:



The molecule of lactic acid is larger than glycolic acid. This means it is slower to penetrate the skin's surface and less irritating than glycolic acid. With prolonged use, it was found to be beneficial in improving dry skin, treating age spots, and decreasing fine lines and wrinkles.


Glycolic acid is composed of the smallest molecule, this means it takes less time to penetrate the skin's surface and stimulate skin renewal (being the most effective), but this also means a greater potential of skin irritation for sensitive skin. It can penetrate the deeper layers of the skin, increasing the rate of dead cell shedding, new skin cell production and collagen formation. With prolonged use, it was found to be beneficial in reducing signs of photo-aging including fine lines, wrinkles, and visible skin imperfections.


Mandelic acid molecules are larger than glycolic acid and lactic acid.

Mandelic acid has been studied extensively for its possible uses in treating common skin problems such as photo-aging, irregular pigmentation, and acne.

  • Its antibacterial properties make it ideal for acne treatments.
  • Loosens blackheads for easy extraction.
  • Excellent for darker skin tones, it does not cause the unwanted, lighter skin tone changes that you might experience with other AHAs.
  • Inhibits melanin synthesis, the cause of dark patches, uneven skin tone and other sun-related skincare issues.
  • Regular use will help to repair sun-damaged skin.
  • Reduces lines and wrinkles without irritation.


  • BHA

The most used form of BHA is salicylic acid. The percentage of salicylic acid is 2% for an over-the-counter product. BHAs are milder than AHAs, yet still effective when used alone, especially on sensitive skin. However, BHAs tend to be more drying than AHAs and can cause skin irritation in some individuals.

Their affinity for oil makes them especially valuable in treating oily skin, as well as those with mild to moderately severe facial acne. With their keratolytic properties, they can dissolve the skin around acne lesions, thus reducing sebaceous follicle blockage by stimulating the release of keratin, oil, dirt and debris. This action eventually minimizes the production of blemishes, blackheads and whiteheads. They are also antimicrobial and work to kill or inhibit the growth of microorganisms, such as bacteria, which is especially beneficial in the treatment and prevention of acne.

Dark coloured skin is at a higher risk of scarring and pigment changes with BHAs than light skin colour.

BHAs can increase sun sensitivity by 50 percent, making it necessary to use a good broad-spectrum UVA/UVB protection sunscreen with an SPF of 15 or higher.

Can I use AHA and BHA simultaneously?

Yes, since they treat different concerns, many formulations contain a pre-dosed combination of AHAs and BHAs to increase their effectiveness for various skin types and conditions. You can also alternate between AHA and BHA products.

Change of seasons is an excellent time to undertake a series of AHA/BHA treatments. However, no matter when you are using them, an SPF must be applied daily to protect the skin from increased sun damage.

G.M. Collin's AHA and BHA home care products




Formulated with 10% AHA (7% lactic acid, 3% glycolic acid), Matrixyl 3000® and Skinmimics© .

A gentle, retexturizing cream that exfoliates and evens out skin tone, and visibly smoothes the skin

*Derm Renewal line: Choose one or the other (never use both products together) depending on your skin type and skin condition(s). Never use both together.




Formulated with 10% AHA (3% lactic acid, 7% glycolic acid), salicylic acid (BHA) and niacinamide.

A highly effective skin resurfacing booster that reveals the next layer of skin and allows the complexion to glow.

*Derm Renewal line: Choose one or the other (never use both products together) depending on your skin type and skin condition(s). Never use both together.




Containing a synergy of essential oils, Salicylic Acid (BHA) and Aloe Vera, this easy-to-use fluid complex effectively soothes and refreshes acne-prone skin without causing dryness and improves the look of localized blemishes and comedones.




An acne treatment for a clear, pure and blemish-free skin. Formulated with:

  • 2% Salicylic Acid (BHA): Helps keeping pores clean to treat and prevent acne.
  • Boldo extract: Visibly drecreases redness and refines skin texture.
  • Niacinamide: Improves the appearance of pores and imparts a more even-looking skin tone.




This invigorating triple action exfoliating powder combines gentle mechanical, enzymatic and chemical actions (salicylic acid - BHA). Activated on contact with water and transformed into a frothy mousse-like texture, this unique exfoliator:

  • Deeply cleanses, removes dead cells and purifies the skin.
  • Allows optimal absorption of product(s) applied subsequently.
  • Leaves the skin visibly soft, smooth and fresh.



G.M. Collin Chemical Peels available in spas

G.M. Collin offers a variety of professional chemical peels designed to:


  • Promote exfoliation of the skin’s surface layers
  • Remove dead skin cells
  • Improve the texture of the skin
  • Reduce the visible signs of aging
  • Diminish the appearance of acne scars
  • Brighten the complexion
  • Leave the skin feeling silky soft.


Discover chemical peels available in spas



Chemical peels should be performed in a series and with appropriate accompanying home care products, for the best results.

It is important to know both the pH of a product as well as its concentrations of AHAs and BHAs. A pH of 3.0 is the lowest allowed for aestheticians to use with a concentration of 30 % AHA and BHA. It is also imperative to know if the acids in the product have been neutralized, in which case they are used solely for hydrating the skin, or if they are buffered, as their action will also be diminished. It is possible to have an AHA product that states it contains 45% acids. However, 15% of these acids could be neutralized and provide only hydration, while 30% are actually exfoliating.