Review – COSRX AHA/BHA Clarifying Treatment Toner

As many a skincare nerd will know, there are some types of products in which the pH is hugely important to the product’s purpose and effectiveness. BHAs, AHAs, or L-ascorbic acid serums are ‘pH dependent’, which means their effectiveness is altered by the pH of the product formulation, or by the pH of the skin they are applied to.

These products tend to perform better at a pH that is lower than the natural pH of your skin. Your skin’s pH hangs around 4.5-5.5, and the ideal pH for these products, such as Vitamin C, can be as low as 2.5. What ends up happening is that some of the effectiveness of these products is used up in the effort it takes to lower the pH of your skin to a suitable range. One way to resolve this is to use a pH-adjusting toner to do the grunt work of lowering the skin’s pH so that the pH dependent products can be more effective at what they do. This is the role of a product like the COSRX BHA/AHA Clarifying Treatment Toner.

COSRX BHA AHA Clarifying Treatment Toner

Full Disclosure: This review contains no affiliate links, and the product was purchased by me. All opinions expressed are my own and are based on my personal use and testing of the product.

What is it?

COSRX’s AHA/BHA Clarifying Treatment Toner is a pH-adjusting toner designed to lower the pH of your skin prior to applying acid products. It should be used immediately after cleansing and before applying actives like AHA, BHA, or L-ascorbic acid.

  • Size: 150mL
  • Price: $16.90 CAD from
  • pH: ~4
  • Texture: Thin and very watery, mists nicely out of the bottle
  • Scent: None
  • Packaging: A medium sized mister bottle
  • Longevity: ~6 months+ at 1-2 sprays twice daily

COSRX Toner Label

Ingredients and pH

Mineral Water, Salix Alba (Willow) Bark Water (10%), Pyrus Malus (Apple) Fruit Water (10%), Butylene Glycol, 1,2-Hexanediol, Sodium Lactate, Glycolic Acid (0.1%), Betaine Salicylate (0.1%), Allantoin, Panthenol, Ethyl Hexanediol

CosDNA breakdown. This is a super clean ingredients list, with only butylene glycol flagging as a 1 for comedogenicity. Careful with the CosDNA listings for this product. The official ingredients list from COSRX contains ‘mineral water’ at the top and CosDNA parsed it as ‘mineral oil’, which is definitely incorrect. I had to check a couple of listings to find an accurate one.

Willow bark extract is a natural source of beta hydroxy acid, which pairs with the betaine salicylate to form the BHA half of the toner. Apple fruit water, a natural source of alpha hydroxy acid, then pairs with glycolic acid to make up the AHA half. There’s something about the ingredient symmetry there that I totally dig.

COSRX Toner pH

My pH strips peg this to be a pH of 4, which matches COSRX’s claim on their website. This pH is appropriately low enough to prep for acid products.

User Experience

The AHA/BHA Clarifying Treatment Toner comes in a no-frills plastic bottle with a spray nozzle. COSRX is well-known for their simple and clean aesthetic, and this bottle is no different. Unlike my other COSRX bottles, however, this one has a printed label that is stuck on rather than being printed directly onto the bottle. The mister works great and provides a very fine, even mist of product. Having said that, I prefer to spray the product into my hands and then pat it in rather than spraying directly on my face. I felt like I needed too many sprays to get enough product on, so now I get by with just 2 sprays into my palm.

COSRX Toner Nozzle

The toner itself is very thin and watery, which lends well to the spray nozzle packaging. It has no discernible scent, and sinks in very quickly and easily. Just like the brand, this is a very get-down-to-business type of product, and so provides a pretty minimalist experience.


True to this toner’s name, I definitely experienced a clarifying effect which I totally didn’t expect. I sometimes get very small red bumps on my cheeks or forehead, and those miraculously disappeared when I brought this toner into my routine. I didn’t expect this because this toner isn’t formulated to provide any true exfolation. While the pH is low enough, the acids are not present in high enough concentrations to do any chemical exfolation, so I’m not 100% sure how it managed to clear up those spots.

COSRX Toner Swatch

In regards to prepping for acids, unfortunately I don’t have enough acids in my routine to be able to verify if it make a noticeable difference. It’s really only prepping for my vitamin C serum, and it does that just fine. I have a BHA now, but I’m only at 2x per week frequency. I’d like to revisit the pH-adjusting toner category once I’m up to near-daily usage of both BHA and AHA because I’m feeling like I jumped the gun on this purchase.

Would I Repurchase?


Maybe? Despite the unexpected clarifying effect, this toner doesn’t feel like a necessary step in my routine right now. pH-adjusting toners are best used to provide a real performance boost to an already robust acid regimen, which I just don’t have. The clarifying is great, don’t get me wrong. I just feel like the toner is being wasted on me because my acid usage is too basic (hurr hurr).

If you’re not like me and are using acids daily in your routine, I think this is definitely something to consider. It could be the performance boost you need to really get the most out of your chemical exfoliants. Up until that point, it feels like an unnecessary extra step when you could be spending money on product that can provide you with its full benefits.

2 thoughts on “Review – COSRX AHA/BHA Clarifying Treatment Toner

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