What is AHA & BHA?
AHA stands for alpha hydroxy acid. BHA stands for beta hydroxy acid, both skin exfoliants.
AHAs are water-soluble acids made from sugary fruits. They help peel away the surface of your skin so that new, more evenly pigmented skin cells may generate and take their place. After use, you’ll likely notice that your skin is smoother to the touch.
On the other hand, BHAs are oil-soluble. Unlike AHAs, BHAs can get deeper into the pores to remove dead skin cells and excess sebum.
How does it work?
The purpose of both AHAs and BHAs is to exfoliate the skin. The way these acids work is by peeling away the bonds that hold the dull, dead skin on the surface of your skin. This causes your skin to naturally shed its spent cells once those bonds are gently and evenly broken. So, although you won’t actually see your skin exfoliating, you’ll soon see (and feel) your skin smoother and younger-looking.
AHAs exert benefits on both the outer (epidermis) and inner (dermis) layers of the skin. AHAs have an exfoliative effect in the epidermis, enhancing the shedding of dead skin cells that are stored at the surface. They do this by gently cleaving the existing bonds between dead skin cells. Once cut loose, those cells can then fall off, or exfoliate.
AHAs also help to promote the development of collage which is why it is such an important ingredient to reduce the presence of fine lines. AHAs do this both by increasing the synthesis of collagen by fibroblasts (the collagen-producing skin cells), and by decreasing degradation of the existing dermal matrix.
BHAs are fat-soluble, so it's good for oily skin and gives pores an increased ability to penetrate. These features explain why a lot of OTC acne products have this ingredient.
BHAs are best known for fighting bacteria and it can be used to treat calluses and other areas of dry skin. It can be used to treat warts in it's form of highest concentrations. This effect happens in a similar way to what AHAs do—by ungluing dead skin cells from each other—but as compared to AHAs, BHAs are able to penetrate deeply into your skin.
Still, we cannot deem neither type of hydroxy acid as “better” than the other, they are both highly effective methods for deep exfoliation. The only difference between them lies in the usage.
Why should I use it?
These are the two forms of acid you have to familiarize yourself with if you want healthy-looking skin.
When choosing between AHA and BHA, it comes down to the way in which you want the products to work. If your issues are deeper, like cystic acne or just bad acne in general, you'll want to use either BHA or an AHA/BHA combination. It will penetrate and get to the root of the problem. For this reason, everyday use of BHAs is totally acceptable.
For an issue like dry skin, you would want to focus on an AHA. An AHA/BHA combo might work depending on your skin type, but when your goal is to exfoliate just the top layer of your skin you should be using an AHA. Unlike BHAs, though, AHA shouldn't be used every day for fear of skin damage—instead, you should use it every other day, at maximum. Use either AHA or BHA right after cleansing and toning in your nightly routine, unless you're instructed otherwise.
Don't forget to checkout Eskandar Moghimipour's "Hydroxy Acids, the Most Widely Used Anti-aging Agents" for more in-depth analysis and we have used them as references.
Threebs' Beauty Spellbook Pick
Like its counterpart, the serum is a hot commodity. Formulated with tea tree water and centella asiatica, the serum is ideal for soothing troubled skin. It also has a dual-layer of plant-based oils that balance moisture levels. It exfoliates, moisturizes, and calms inflammation all in one step.
The Some By Mi Miracle Toner is formulated with AHAs, BHAs, and PHAs to ensure an effective exfoliation and noticeable skin improvement within 30 days. The low pH toner is surprisingly safe for sensitive skin (it’s dermatologically-tested), and the high-concentration of the ingredient tea tree water extract is both soothing and promotes clear skin.
In addition to its balancing and moisturizing properties, the toner also serves as a dual-function brightening and anti-aging product, thanks to ingredients like niacinamide and adenosine.
One of our most-loved products of all time. You can think of The Ordinary's AHA 30% + BHA 2% Peeling Solution as a 10-minute exfoliating facial that combines 30% Alpha Hydroxy Acids (Glycolic / Lactic / Tartaric / Citric) with 2% Salicylic Acid to improve visible radiance and texture in no time.