Review: Cosrx AHA / BHA Clarifying Treatment Toner vs Mizon AHA BHA Daily Clean Toner

This week I'm going to be doing a mini-review of the Cosrx AHA/BHA Clarifying Treatment Toner and comparing it to my trusty Mizon AHA BHA Daily Clean Toner.  Why a mini-review, and not a full review, you might ask?  You'll see shortly.

Before we start, I just want to add a note about what I expect out of these types of toners.  My expectations are pretty low, actually:
  1. I expect them to be a suitable pH to lower my skin's pH after cleansing to prepare it for my actives (Vit C, BHA, and AHA), 
  2. I expect them not to leave residue on the skin that would interfere with the ability of my actives to work directly in my skin, 
  3. I expect them to be non-irritating.  
That's all I need.  With such minimal expectations (I pay no need to the brand's claims such as "prevents whiteheads, blackheads, and blemishes with the perfect blend of all-natural ingredients and mineral water to rejuvenate and replenish your skin."  Yeah, no.  It's a just a pH-adjusting toner.  Its job is to ready my skin for my next steps, I'm not expecting magic here.  Most people don't even need a pH adjusting toner, I just live in the desert so my skin dries out too fast to wait around for it to naturally adjust itself.  But I do, and it does, so here I am.  Onward!

In this post:
  • Ingredients overview of Cosrx vs Mizon
  • A small pH testing snafu and ensuing rage-shopping
  • pH of Cosrx Natural BHA Skin Returning A-Sol
  • pH of Mizon 8% AHA Peeling Serum (control) and AHA BHA Daily Clean Toner
  • pH of Cosrx AHA/BHA Clarifying Treatment Toner 
  • My observations and experience with Cosrx vs Mizon
I'm also incredibly surly today because I realized halfway through my prep, when it was too late to stop, that I had ordered the wrong size of test tubes.  RAGE!

Ingredients overview of Cosrx vs Mizon

Let me start by saying I was really looking forward to trying out the Cosrx AHA BHA toner, because I absolutely love the Cosrx BHA Blackhead Power Liquid, and I am reasonably satisfied with the Cosrx Natural BHA Skin Returning A-Sol spot treatment.  

I have repurchased 5 bottles of Mizon's AHA BHA toner (to date) and obviously I am very happy with it, but it is constantly selling out and is hard to find, whereas Cosrx products have been pretty easy to source so far.  Would the Cosrx be a dupe of the Mizon?  I hoped so!

Even more encouraging was the ingredients breakdown between them, with Cosrx seeing to be the clear winner:

Mineral WaterWater
Salix Alba (Willow) Bark WaterButylene Glycol
Pyrus Malus (Apple) Fruit WaterAlcohol
Butylene GlycolGlycerin
1,2-HexanediolCarica Papaya Fruit Extract
Sodium LactatePortulaca Oleracea Extract
Glycolic AcidArnica Montana Flower Extract
WaterArtemisia Absinthium Extract
Betaine SalicylateAchillea Millefolium Extract
AllantoinGentiana Lutea Root Extract
PanthenolGlycolic Acid
Ethyl HexanediolPEG-60 Hydrogenated Castor Oil
Lactic Acid
Sodium Lactate
Salicylic Acid
Disodium EDTA

As you can see, there are a lot fewer ingredients in the Cosrx.  Neither one of them have any 'big' flags on Cosdna: click here for the Cosrx Toner entry on Cosdna, click here for the Mizon Toner entry on Cosdna.  The 'worst' offender is the Salicylic Acid in the Mizon toner, but of course it's supposed to be there as that's the BHA, and it's in low concentration.

I notice that the Mizon has moisturizers listed much earlier than Cosrx, although it does contain alcohol which the Cosrx dos not.  I would have thought that would mean the Mizon would be less irritating, but I'm getting ahead of myself.

Let's get pH testing!

A small pH testing snafu and ensuing rage-shopping

I use a digital pH meter with a two-point calibration for pH testing acids, as pH strips can react oddly with acids and give inaccurate readings.  I do still use pH strips for general products, especially things with a lot of lipids, like creams and emulsions.  You can learn more about my kit here: Better Beauty Through Chemistry: Unboxing of my digital pH Meter supplies.

As I grumbled about in that post, I was unhappy with not having a suitably long-and-narrow glass container that would allow me to sacrifice minimal product yet still completely immerse the electrode of the digital meter.  I was unimpressed with my DIY emergency solution to use wine glasses, and thought I'd be all smart and get test tubes off Amazon.  Designed for the purpose and all, amirite?

Well, due to the weather delays in shipping, I received them just in the nick of time for this post and when I unwrapped them, my relief turned to disbelief, despair, and then rage very quickly.

Buffer liquid of pH 7.01 and buffer liquid of pH 10.01 pictured at far right.
As you can see in the image, the test tubes are approximately twice the height my meter needs in order to reach the liquid at the bottom.


I am not about to waste an entire bottle of product to bring the surface of the liquid up to a level that the pH meter needs, so I said a bunch of really foul words that made my husband flee to his gaming computer (with headset) and angrily stormed onto Amazon to find 75mm test tubes.  I would have realized that's what I needed in the first place if I had not been too lazy to dig my digital meter out of storage and measure the darn thing.

Did you know you can buy wine on Amazon?  Amazing the versatility it has.  Anyway, back to testing with my wine glasses 'shabby chic' method.

pH of Cosrx Natural BHA Skin Returning A-Sol

pH result: 4.32

That wineglass.  Ugh.  ANYWAY, this test result is quite interesting because I have been asked (and have been wondering myself) where exactly this product goes in one's routine order.

The order of your products is pretty important when you're working with pH dependent products like actives.  You can read more here: Putting your products in order, including pH dependent acids.

As I explain in that post, normally BHA goes before AHA, due to it requiring a lower pH to be effective (below 4.2) and also because it's oil-soluble and does a great job of clearing out your pores so your AHA product has a clear shot at your skin afterward.  However, the A-Sol is neither high enough in concentration (according to the back, it's only 0.5% ) nor low enough pH for exfoliation.  

That doesn't mean that it's not going to help your skin, as BHAs do have other benefits even at a higher pH, but it does mean that it needs to shuffle to the back of the line and go on after you are done all your other actives.  I still like to give it a bit of a wait time to work on my skin before I add any layers, though.

pH of Mizon 8% AHA Peeling Serum (control) and AHA BHA Daily Clean Toner

pH result: 3.83

I have tested this product before, in the Better Beauty Through Chemistry: Unboxing of my digital pH Meter supplies post, but I am testing it again today for a few reasons.

One, I want to show how consistently the Mizon AHA serum tests (this is my 5th bottle, and all have tested in the same range), and also to provide a relative ph result to compare the others to.  3.83 is definitely firmly in the 'exfoliation' range, as 4.5 is the high end for AHAs.

I also am testing this instead of the Mizon AHA BHA toner, because as you can see from the first picture on this post, I am dangerously low and could not afford to waste the product.  However, I do have pictures of its test results in the link above, which came out to 4.30 for the Mizon Toner.

Just let that sink in for a second, if you would ... the Mizon AHA BHA toner is 4.30, and natural skin pH is between 4.2 and 5.6 [source and more info here].  The Mizon 8% AHA Peeling Serum is between 3.83 and 3.89, but it is also a serious exfoliant that I don't use daily.  Ready for the Cosrx toner result, by comparison?

pH of Cosrx AHA/BHA Clarifying Treatment Toner 

pH result: 3.85

Say what.

And thus the great mystery of why my skin was reacting to this toner is solved, at least this is the most plausible explanation in the absence of any other explicable factors.  I'll get into this more below.

I have no idea why this 'toner' has such a low pH, because it's really completely unnecessarily for a 'prepping' step be right down-n-dirty in the exfoliating pH range.  Also, this product has low concentrations of both BHA and AHA, so it's not even packing much exfoliation ammo to begin with, so why have such a low pH?  It makes no sense to me, and it's overkill for what pH-adjusting toners are supposed to do ... aka, adjust the pH of the skin after cleansing, in preparation for pH-dependent products, without irritating the skin.

My observations and experience with Cosrx vs Mizon

As you've probably guessed, I'm really not happy with the Cosrx AHA BHA Clarifying Treatment Toner.  It's one of those products where my head tried to convince my skin that it was really ok:
"No honest, it's really better than the Mizon, look at the ingredients list!" 
"But it's so easy to source and it's so cheap!" 
"Look, it comes in a handy spray bottle!"
Yeah, no.  Somehow, the Cosrx Toner is very irritating to my skin, and my skin loves acids.  Looooves them!  I tested this product, despite the burning face effect, for a whole week, trying every application method I could think of.  I applied it with a cotton pad as Cosrx's website directs, I tried spraying it onto my hands and then patted onto my skin like I do with the Mizon, I even sprayed directly onto my face with enough distance that it was a fine mist.


I tested it on the left side of my face, with the Mizon as a control on the right side of my face.  From the very first application, I could feel that my left side felt hot and irritated, whereas the Mizon side was happy as usual.  The sensation persisted all day, which is also uncommon for me.  I figured it was the application method, but even as I switched it around in ensuing applications, the result was always the same.  The Cosrx side persisted in having an irritated sensation.

I even tried patch testing it on the Mizon side, just to make sure it wasn't some sort of inexplicable effect on only the left side (was I sleeping on my left side all of a sudden?) but nope.  Same effect.

This is super disappointing to me because I expected something with 1. no alcohol, and 2, fewer ingredients to be gentler, safer on the skin, and of course less irritating.  What the heck, Cosrx?!

I did pH test it with my strips but got a really confounding result, so I decided to hold off until I could set up and calibrate the digital pH meter, and when I finally pH tested everything today, it made more sense.  3.80 is sort of unnecessarily low, and therefore potentially irritating, for a product that doesn't contain enough concentration of acids to function as a 'true' exfoliant.  There is nothing wrong with something being sub-pH 4, it's just strange that it is that low when it doesn't actually do anything.

As you can see in the close-up of the label, it contains only 0.1% AHA and 0.1% BHA, which is hardly enough to justify it as its own independent exfoliator.

Moreover, if it's not meant to be an exfoliator, why bother with a super low pH, that dips below the 4.2 threshold?

Of course my immediate thought was that I must be reacting to something in the product, but there are no flags in the ingredients for me, so I have to conclude it must be the pH.  I'm not convinced that the pH is the reason for the irritation, but I know others have had the same experience, so there's something up with it.  In the face of a total lack of anything else I can come up with to cause the irritation, I'm reluctantly going to conclude it might be the pH because there's nothing else I can think of that would cause it.

All in all, this was a huge disappointment and as you can see from the image, I'm back to my dire need to find either a replacement for the Mizon or somewhere that stocks it so I can repurchase it.  Obviously, it's possible that my bottle was a one-off defect of some kind and it might work perfectly for you, but it's definitely not something that I will be recommending to anyone.

Update:  After being 'confirmed' discontinued by an official Mizon distributor, it's now available again, and I'm thrilled. Where to get the Mizon toner: Amazon Prime for $20 | eBay for $18 | Testerkorea for $25 |

Now I've got to figure out if there's a way for me to dilute it without playing pH roulette (it's not as straightforward as 'add pH 7 water to pH 3 liquid and get pH 5!', for example) or whether I just need to banish it to my drawer of duds and never speak of it again.  Yep, it's going to be the latter.  Goodbye, Cosrx AHA / BHA Clarifying Treatment Toner, we shall not meet again.

Ah well, you can't win 'em all!

**Disclaimer: All products reviewed/mentioned in my blog, are 100% purchased with my own money, with a single exception of a press sample I tested & reviewed in 2015 which swore me off of them forever.  This blog contains  both affiliate and non-affiliate links, and clicking the former before you shop means that this blog may receive a small commission to assist in this blog supporting itself.  Please see my Contact Info & Disclaimer policy for more information. 


  1. Thanks so much for this review, Cat. I am a huge fan of the Mizon Toner and have been looking for an alternative since it can be pretty difficult to find, and I've seen quite a few people buzzing about the Cosrx one so I considered giving it a try. Looks like I'll just have to continue hunting down my Mizon until another alternative pops up!

    1. Agreed, I don't know why it's so hard to find! T^T I think I might just go Haulzilla on it next time it stocks and get a bunch of back ups. I hate doing that, but the Cosrx is just way too irritating for me to be subjecting my face to on a twice daily basis. :(

  2. Would you recommend the CosRX toner for someone who's allergic to alcohol? I can't use the Mizon toner so I've been on the hunt for an alternative.

    1. I wouldn't recommend the Cosrx toner, period, but if you have a very hardy, tough face that is not sensitive to anything other than alcohol, maybe?

      I am still unclear as to why this irritates my skin so much, the only culprit I can think of is the pH but to be honest, that's just process of elimination since there aren't other ingredients that I react to, so YMMV. It might work for you, but it's still not a russian roulette spin I'll be suggesting anytime soon. :(

    2. I will probably skip this too then. Thank you for your great review! The search for me continues!

  3. This comment has been removed by the author.

  4. That's interesting, because to me the Cosrx toner feels like putting water on my face while iirc the Mizon had a little bit of tingle. So the Cosrx feels much milder, to the point where I cannot tell if it's doing anything. Which was the same experience I had with the Mizon ; apart from the tingle from the alcohol there didn't seem to be anything. Neither one do anything for me.

    1. Interesting! Skincare is so YMMV; sometimes you just never know how specific products are going to react with your skin.

      "Neither one do anything for me."

      Yeah, I read the wild claims of the marketing for these types of products and have to roll my eyes ... how much do they really expect a 0.1% concentration to do? I expect them to help lower my skin's pH more quickly (my water is pretty hard, and is above pH 7) but that's about it.

  5. I have almost the same type of skin as you and I was really interested in getting Mizon's toner. I've been looking for it everywhere and it seems like it's sold out all over the place. I was then contemplating getting the Cosrx one, like you said is cheaper and the ingredient list is shorter than the Mizon one. Not to sure about trying Cosrx now, where do you think I can find the Mizon please ?

    (Just discovered your blog.. And I have to say, I love your spreadsheet organization ! )

    1. "Not to sure about trying Cosrx now, where do you think I can find the Mizon please ? "

      I usually stalk roseroseshop until they restock it, and then grab it there. Mizon is free shipping + a $2.50 tracking fee for the entire order, so it's my favourite place to stock up on Mizon goodies

      "(Just discovered your blog.. And I have to say, I love your spreadsheet organization ! )" Spreadsheets 4 lyfe! <3

  6. Hello! I have a question :)

    The CosRx A-Sol has a pH of 4.3, and not enough concentration (or low enough pH) to exfoliate,

    The CosRx AHA/BHA Toner has not high enough concentration to exfoliate, but has that super low pH of 3.85.

    You mentioned in another post that you like to use your Mizon AHA/BHA toner after your actives to clear the gunk off your skin before moving on to moisturizing agents. My question is, since the A-Sol has that higher pH and the AHA/BHA Toner has a lower pH, but neither have the concentration to exfoliate, can you mix them together and apply with a cotton pad to clear the gunk in the same manner you use your Mizon?

    I ask because I have both of these products and I would like to get some use out of them lol.


    1. "can you mix them together and apply with a cotton pad to clear the gunk in the same manner you use your Mizon?"

      Unfortunately pH is a factor of 10 (meaning pH 4 is 10 times higher than pH 3) so it's not really possible to mix things together and have a reliable outcome. Regardless, neither the Cosrx Toner nor the A-Sol have a high enough concentration of acids to work as an exfoliant.

      The A-Sol is more of a skin treatment, so I would use it as such, and the toner to prep the skin after cleansing.

      I hope that helps!

  7. I am going to be writing a review on the CosRX toner and I have quite the difference experience than you. My skin loves it and there is no irritation at all. I have very oily skin, not sensitive, so maybe that is it.

    1. I'm glad to hear that your skin liked it! That's the thing about skincare, you just never know how things are going to work for you. Ingredients are just one piece of the puzzle.

      I may not have even noticed the different/thought it was normal if I had not been comparing it to the Mizon side-by-side. (Cheek-by-cheek?)

  8. I seriously need help. I just bought a slew of new products to fill in gaps in my routine, including the Mizon AHA & BHA toner, and I can't figure out which order everything should go in. The last thing I want to do is get it wrong and have my face blow up. I would prefer to be pretty. Would you be up for a bit of coaching? I can write up everything I'm using, all the new stuff and how I think I should be using, along with info on my skin, and maybe you can give me a tip or steer me away from something obviously wrong? I'm new to Korean skincare and I'm feeling the newbie nerves. Thanks for your awesome article!

    1. Also no idea why that says "unknown". I'm me!!

    2. Oh gosh, I am so sorry I did not even see this comment! I actually have a post that is specifically about putting things in the right order, actually! :)

  9. This was a really interesting comparison!

    I've just recently read this post by SkinandTonic:

    And am now hunting down a acid toner. The P50 raved about there will be too difficult for me to get, living in Europe, but that one is at a ph level of 3! So I'm considering the CosRX toner as an alternative since it also has a low pH. But since you mention that this level of ph is unnecessarily low, I'm now pretty confused. Is it just because it happened to be irritating for you, or is there another reason this low ph is problematic?
    (I'm very new to all this so sorry if I misunderstood something)

    1. "But since you mention that this level of ph is unnecessarily low, I'm now pretty confused. Is it just because it happened to be irritating for you, or is there another reason this low ph is problematic? "

      The pH is not necessarily problematic, just that this toner was mysterious irritating to me (and others as well, who do not have sensitive skin, like so the pH is the only culprit I can think of. :)

    2. Ah, I see!!

      I'm not even sure why the lower pH is necessary in that article.. It suggests between 3-4.. but even 4-5 is more acidic than natural, and should be good enough?

  10. I'm a little confused as to why the Cosrx Asol one is not a good pH adjuster. Per your tests, it has almost the same pH as the Mizon toner. Am I missing something?

    1. The Cosrx A-Sol is an acne treatment with a heavy amount of propolis. It's a lovely product but it leaves too much residue on the skin, whereas you are looking for something that will leave the skin 'bare and clean' after use, and therefore ready for acids.

      I hope that helps!

  11. Quick question, let's say my second wash is a low pH cleanser, the Innisfree Jejubija gel cleanser. It's super gentle and according to picoprince has a very low pH. Do I still need a pH adjusting toner?

    1. I would recommend pH testing any cleansers you have yourself, as well as your water. Personally, as I use very gentle actives meant for daily use, I prefer to err on the side of caution and pH adjust my skin beforehand so I know my actives are getting a head start and I am maximizing what I am getting out of them. YMMV of course! :)

  12. Hi!please answer this question :(
    My daily night routine is using Jeju Vulcanic Toner Innisfree and then ost c 20 serum. So, should I using AHA/BHA Clarifying Cosrxs before using ost c20?
    Thanks btw for this amazing information! :)

  13. I love love love your blog! I just recently discovered korean skin care and the more products I discover the more i need Google. Your blog came up because you have several articles that answered my questions. I am also very fair skinned- like burn in 8 minutes fair- and sensitive so it's nice to get an honest opinion from someone with similar skin.

  14. Hi! I really want to try the Mizon AHA/BHA toner but I hear so many negative things about alcohol damaging skin? should i be worried about the alcohol content in Mizon toner? Thank you!

    1. Hi there!

      I actually turned this over to The Snailcast so you could have the benefit of 4 blogger opinions (and one cosmetic formulator) to help with this question! :) When the episode is released, it will appear on :D

  15. Hi! This is kind of unrelated to the post but, can I just use BHA instead of AHA?

    Poor college student here ;o;

    1. It really depends on what you're looking for it to do :) Are you trying to prevent sebum and crud from building up in your pores (BHA), or are you trying to slough off the layers of what's already there (AHA)?

  16. Hi! I read your post and you said that a-sol is an acne treatment and you'd use it after all your actives,

    "but it does mean that it needs to shuffle to the back of the line and go on after you are done all your other actives"

    if I only use the ost c20 serum & a-sol, does it mean I should use the ost c20 serum first then the a-sol? All this time I use the a-sol first because the ost c20 serum leaves sticky feeling to my skin and I think it's better to not putting any layer after that. What's your suggestion? Thanks xx

  17. hello, just found your blog and there is so much good information here! thank you! A quick question, is there a safe way to put my Etude house pore toner into another small bottle without the risk of loosing the chemical features? the etude house toner comes in a see trough bottle so there is no problem with lighting, but should I clean the new bottle with alcohol or something before? thanks for the time!

  18. hai there :) ! thanks for writing a blog thats full of information and easy to understand for people like me, who wants to know but couldnt ask anyone. ur blog is so resourceful, especially the part where u explain about all the acid and actives and putting it in the right order.

    so after reading here and there (some of the links u gave here) i decided to try on acid, i put cosrx aha/bha toner pm only for a few days, and applying bha liquid after. lets say after a week using, i start breaking out a lot. few of them cyst and painful, some of them are just small pimple with the head and redness all over my chin + foreheads. (the acne are there too, nothing on my cheek as i rarely get acne there) so i was just wondering, is this normal? is it supposed to be a reaction of closed comedones and all that started coming up to the surface? i stop using the acid for now, till i figure whats happening and my face calming down. will be much appreciate for ur advice. thanks again !