Everything You Need to Know About AHAs & BHAs

Chemical Exfoliation



If you are reading this you are probably like I was and cringe at the thought of putting something labelled an acid on your face. I put it off for the longest time, sticking to my trusty manual exfoliators but when I finally had the courage to try it, I fell in love! I still use manual exfoliation every now and then but now I am fully converted and would rather use my BHAs and AHAs when and if I need them instead.

So what are AHAs and BHAs?

Acids used in chemical/active exfoliators are put into two seperate categories. One is alpha hydroxy acid (AHA) and the other is beta hydroxy acid (BHA). You may find that many people use an AHA and BHA in conjunction with each other, in order to maximise effectiveness however it is more than okay to do them separately or not use one at all. They go after your cleanser and toner! The most important thing to keep in mind is that they are actually capable of altering your skin cell structure or function of skin when used properly (they are actually classified as a drug rather than cosmetics) so they do have to be taken seriously. They are both available in differing degrees of strength so it is best to work your way up!

 Some of the most popular chemical exfoliants in the K-Beauty market.

Some of the most popular chemical exfoliants in the K-Beauty market.

the aha (alpha hydroxy acid).

An AHA is chemical exfoliant are derived from natural substances that targets the top layer of your skin. This way it targets the top surface such as closed comedomes, fine lines, scarring and uneven textures. Some common AHA products contain glycolic acid (sugarcane) which contains teeny tiny molecules that are able to penetrate skin deeply and with ease. These molecules break down the top layer of your skin. They do this by dissolving sebum and other icky things that your skin produces naturally = fresher skin! AHAs also can contain the gentler lactic acid (sour milk) that also works to break down the 'glue' between skin cells causing them to slough off to reveal the newer and fresher skin underneath. Due to its ability to break down the 'glue' between your skin cells, lactic acid is a good one for helping fade acne scarring and evening out the colour of your skin.

They are best used if you have normal/sensitive skin and have skin concerns that focus on things such as redness, pigmentation, uneven texture. 


A BHA is the second form of chemical exfoliant that delves deep into the pores to clear the source of the problem. BHAs are oil-soluble and therefore are able to reach deeper into the skin and pores unlike an AHA which is water-soluble. It is great for acne-prone and oily skin because of its ability to penetrate the pores. BHAs helps to get rid what sits under the skin, such as blackheads and cystic acne. It is also usually recommend as an exfoliator over manual exfoliators due to the harsh nature of manual exfoliators. Harsh sugar scrubs can open up existing acne and spread around the bacteria thus creating new lil critters so actives are key for acne-prone skin. A popular BHA is salicylic acid, which when combined with betaine (betaine salicylate) is found in a lot of Korean beauty products these days, such as the COSRX Pimple Pads (this is a real fab product, you can read my review here). Betaine salicylate is a much gentler form of BHA- so it might be better to try when you're just starting out.

They are usually recommended for acne-prone, oily skin. If blackheads or deep painful pimples are your big concern go with this fella.

It is important to note that you may have a reaction as these are, first and foremost, acids. As always, if you know you are sensitive, it's wise to avoid them. Make sure that you test the product on a small patch of skin (the jaw is a good one) to make sure you don't react.

things to be aware of.

  • If you are very new to skincare or the 10-step routine then it might be best to hold off on the chemical exfoliators. This is because you will not know what your skins tolerance levels or ingredients you have problems with. Actives can be a pretty serious business and are not to be taken as lightly as manual exfoliation. 
  • Salicylic acid is pretty harsh and so it might be best to begin with betaine salicylate. However, if you have very sensitive skin or are on medication, such as Accutane then it might be best to forgo chemical exfoliation altogether. 
  • Go easy on the BHAs, when I first used it I used way too much on my chin and woke up to a very dry and flaking chin. 
  • You must leave a 30 minute wait time after each use in order to allow the acid to work. In other words, apply your BHA and wait 30 minutes, then apply your AHA and then wait 30 minutes before applying your next step. 
  • Do not use it every day- getting your skin used to acids is something that must be build up over time. To start, try once a week for a month or two and then increase it slowly. I don't use chemical exfoliation anymore than two days a week maximum but that's personal preference. 
  • You are going to *need* to be incorporate SPF into your skincare routine every morning if you use an AHA. You really should be doing it anyway, but AHAs cause photosensitivity which means that your skin it more vulnerable to the sun and burning. I have a whole post dedicated to sunscreen in all its glory here.

Like with just about everything, if you are pregnant, on medication for acne, or generally under a physicians care for your skin make sure you check with your doctor before adding any actives to your routine.

 The sunscreen I use: Missha All Around Safe Block Essence Sun SPF 40 PA+++

The sunscreen I use: Missha All Around Safe Block Essence Sun SPF 40 PA+++


I have one BHA and one AHA currently in my arsenal and am a big fan of both. I use the COSRX Blackhead Power Liquid as my BHA which uses the gentler betaine salicylate. Because of this I have no experience with salicylic acid and cannot give an opinion on that one. I have a fairly normal skin type nowadays, if anything it leans more towards an oily type. I don't fight with those nasty and painful cystic acne anymore (unless it's hormonal acne *sigh*) so the BHA is not so much my concern However, I do still struggle with blackheads and have noticed that the COSRX Blackhead Power Liquid has done a good job of keeping them at bay every time I use them. It is important to note this is not a miracle treatment and unfortunately if you have large pores you will likely still have to deal with blackheads. Rather, my experience with this BHA, is that definitely it helps reduce them. When I first used it I got a bit overzealous and wanted the blackheads gone right then and there and woke up to dryness and a bit of flaking the next morning. Definitely one to be cautious of.

 My favourite AHA of all time: 23 Years Old Badecasil 7 in 1 Solution

My favourite AHA of all time: 23 Years Old Badecasil 7 in 1 Solution

My AHA on the other hand is my holy grail. I love it so so much and couldn't live without it! I use the 23 Years Old Badecasil 7 in 1 Solution and have no intentions of trying another AHA any time soon. My main struggle is closed comedomes (those pesky skin-coloured bumps on your skin) or uneven texture. This AHA literally gets rid of them- when I check the next morning, they have either significantly reduced and are on their way out, or are already gone! I have heard of some people using it every day, such as YouTubers Taylor RBiibiiBeauty and general Instagram users but I only use it when I notice my skin texture is a little rough (which is about once a week.) I don't think I will ever use chemical exfoliators more than twice a week as I personally don't need to.

  • A full review for the Badecasil Solution is coming soon!

final notes.

As Fiddy Snails suggests, it is best to think of actives as medicine. Use them when you have a specific problem you want to fight, do not use them willy nilly. Acids are not for everybody. If you're struggling with clogged pores and blackheads then you may only need to use a BHA. Similarly, if you're dealing with post acne problems, such as pigmentation and uneven texture, then AHA is your best bet and you can forgo the BHA. It is all about tailoring your skin routine to your skin. Ultimately it is up to you whether or not you need them in your routine.

I hope this helped break down the world of chemical exfoliation for you. It took me a while to fully wrap my head around it so if this helps you even just a little bit, I will be pleased as punch.


New Zealand/ Australia:

Hikoco- (COSRX BHA) goo.gl/LS3qVj (BADECASIL) goo.gl/vGNHFo
Nashi Lab- (COSRX BHA) goo.gl/pfV9QW


Amazon- (COSRX BHA) goo.gl/9f7PgC (BADECASIL) goo.gl/sQ9625
Wishtrend: (COSRX BHA) goo.gl/3DpIZ1 (BADECASIL) goo.gl/Fgcb15
Style Korean: (COSRX BHA) goo.gl/t3m0TJ (BADECASIL) goo.gl/FYqr4W









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