Okay basic definitions first. An AHA, or Alpha-Hydroxy Acid, is an acid found in foods (like milk, apples, grapes, etc). The ones found in your skincare are generally synthetic, but lactic acid for example is originally derived from milk. They work by breaking down the substance that holds your skin cells together. BHA, or Beta-Hydroxy Acid, is the structural name for salicylic acid. It's obviously also a chemical exfoliant but is lipid soluble as well (it cuts through oil). More on this later. Your skin exfoliates a huge amount of dead skin daily, but as we age this process slows down, meaning that supplementing with chemical exfoliants becomes helpful in keeping your skin smooth.
AHAs are water soluble and have small molecules meaning they can penetrate the upper layer of the skin and really work to exfoliate dead skin cells away. They act in both the dermal and the epidermal levels, because the exfoliation prompts cellular renewal. There are many many many different kinds of AHAs: Lactic Acid, Glycolic Acid, Tartaric Acid, Malic Acid, Citric Acid, etc. As I talked about in my acids post, I really love glycolic as it has the smallest molecules and helps the most (personally) with keeping my skin smooth. Because AHAs exfoliate away dead skin, you're left with brighter, fresher skin at the surface. Working mostly at the surface layers of the skin, they're best for helping with things like reducing signs of aging and sun damage. Because of their water solubility they are ideal for drier skin (but anyone can use them)! AHAs have also been shown to increase skin barrier function (keeping nasties out and moisture in), increase epidermal thickness (making skin look more plump), and restore hydration. Major win.
BHAs are oil soluble, obviously making them more ideal for oily skin. It is found naturally in willowbank, but is generally synthetically produced also. Salicylic Acid is awesome because it can work inside the pores to break down the buildup of oily clogged up dead skin. It's also both antimicrobial and anti-inflammatory meaning it helps combat acne bacteria and soothes skin. Basically a super ingredient, right? BHAs are generally less irritating than AHAs (although they reap the same benefits), so are much better for sensitive skin.
Both AHAs and BHAs need to be absorbed into the skin, so your glycolic face wash really isn't doing that much. Sorry. I'm not saying there's anything wrong with using these, you're just not really benefitting. AHA and BHA serums are my favourite, but you can also find masks and moisturizers as well. Like I said, I personally love Glycolic Acid so my favourite products are the Pixi Overnight Glow Serum, Pixi Glow Tonic, and The Ordinary Glycolic Toning Solution. BHA Products I love include Mario Badescu's Drying Lotion and the Paula's Choice Skin Perfecting Liquid. I do also love Sunday Riley Good Genes (Lactic Acid) and am going to be trying Exfolikate! I've recently been trying out The Ordinary's AHA + BHA Peeling Solution (terrifying), and loving the results. This contains Glycolic, Lactic, Tartaric, and Citric Acid as well as Salicylic Acid so it really packs a punch.
How often you use these depends on your skin. I have previously used something like Good Genes every day and had no negative effects, but if you have more sensitive skin this probably isn't the best idea. I've cut my routine back a bit and am trying to be more consistent so this is what works for me: I use the Pixi Glow Tonic or Ordinary Toning Solution Nightly, every other night I'll use one of the serum-like products (ie Overnight Glow, Good Genes, Skin Perfecting, etc), and once a week I'll use the AHA + BHA Peeling Solution. This is in conjunction with my moisturizers, etc. Please remember that this works for me and may not work for you. listen to your skin!!
I hope you all find this helpful, and please ask me any questions you have!
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