Review – COSRX BHA Blackhead Power Liquid

My skin has always been really receptive to acids, despite having rosacea. Getting a daily BHA into my routine has been my most recent #skincaregoal, and for my first Asian BHA product, I purchased the one most people probably already know about: COSRX’s BHA Blackhead Power Liquid. It’s about as gentle as it gets for a BHA, which was important to me because I prefer using weaker acids on a daily basis rather than stronger ones a couple of times a week.

cosrx bha 1

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 BHA Blackhead Power Liquid is a gentle BHA chemical exfoliant. BHAs are excellent at penetrating and cleaning pores, and are ideal for preventing clogs, blackheads, and acne.

  • Size: 100 mL
  • Price: $18.74 CAD from
  • pH: ~5.0 (although the site claims ~4.0)
  • Texture: Thin, watery serum
  • Scent: None
  • Packaging: Frosted plastic pump bottle in COSRX’s typical aesthetic

cosrx bha pump

Ingredients and pH

Salix Alba (Willow) Bark Water (67.8%), Butylene Glycol, Betaine Salicylate (4%), Niacinamide, 1,2-Hexanediol, Arginine, Panthenol, Sodium Hyaluronate, Xanthan Gum, Ethyl Hexanediol.

CosDNA breakdown. The only flag is butylene glycol [1] for acne.

A very short ingredients list in typical COSRX fashion. The BHA in this formula is betaine salicylate at 4%. That might seem a high percentage for a BHA because most BHAs we know come in concentrations of 2% or less. However the 2% concentrations are of salicylic acid, and betaine salicylate is a much weaker acid in comparison. As a result it’s also much gentler than salicylic acid, so if you have problems with using SA, then a product with betaine salicylate might be worth looking into. The willow bark water is also a naturally occurring source of BHA, however it’s effectiveness compared to salicylic acid is questionable at best, and I wouldn’t depend on it to deliver the same results in a formula on its own.

BHAs stands for beta-hydroxy acids, and they are a family of chemical exfoliants that are particularly recommended for acne-sufferers and oily skin types. BHAs are oil-soluble and can penetrate and kill bacteria within the pores to deep clean the skin rather than only clearing the gunk away at surface level. Where other chemical exfoliants are great at treating active acne and dealing with the aftermath, BHAs are excellent at preventing acne from forming in the first place. They are also anti-inflammatory, which is great for people with rosacea and/or sensitive skin.

Even with all those benefits, it takes more than just the presence of a BHA in a product in order for it to be an effective exfoliant. The pH of the formulation is also important, since the environment needs to be acidic enough in order for the acid to function. For BHAs, this is understood to be a pH of ~3-4. As you can see in my pH strip test, both of my bottles of Blackhead Power Liquid tested to be closer to a pH of 5. Early in 2017, customers noticed that they were unable to reproduce the claimed pH of 4 with their products, and some reached out to COSRX over Instagram to see what was up. COSRX responded extremely quickly, and after a brief investigation came back and told us that their chemists had changed the formula because they were having difficulty keeping the product stable at the lower pH, though the efficacy should be unaffected. Getting a stable formula at the lower pH would require the addition of alcohol, which they knew a sizable portion of their customers wouldn’t want. Being the fantastic consumer-friendly brand they are, they asked the community for their opinion on whether they would prefer a higher pH product without alcohol or a lower pH product with alcohol. As far as I can tell, most people vehemently preferred the version without alcohol, so it seems like COSRX chose to stick with the higher pH formula.

So does the higher pH mess with the efficacy? The short answer is that it isn’t really clear. The evidence around BHAs being effective at pH of 3-4 are for the most part referring to only salicylic acid, not other BHAs such as betaine salicylate. The lack of information specific to betaine salicylate means that it could very well be just as effective at a higher pH than it’s more acidic cousin. I’m inclined to believe that this is the more likely scenario, since I haven’t heard much discussion from the community about a lack of effectiveness of this product. Without more scientific data, though, it’s not really possible to know the full story. So I’ll just have to leave this topic with a gigantic question mark for the time being.

cosrx bha ph


This BHA comes in COSRX’s standard frosted plastic pump bottle with the label inked right on the bottle. I love how COSRX has such minimalist packaging that still feels sturdy and not crappy or cheap. The simple aesthetic looks clean and has a clinical elegance to it instead of looking like low-effort design. They make a conscious choice to not pour money into designing fancy packaging, but the packaging they have is designed extremely well in my opinion.

The serum has no scent that I notice, and the liquid is quite watery. It sinks in quickly, and easily, and I normally let it dry down for a few minutes before starting my hydrating layers in the morning. I used to aim for around a 30 min wait time both after my morning Vitamin C serum, and after this BHA because, allegedly, pH-dependent products need some time to work on your skin without interference in order to get the best results. I’ve found little scientific support for that, and a whole lot of anecdotal evidence from people saying they don’t have a wait time for their acids and they did not notice a change in effectiveness. With how early I already get up in the morning, and how long my morning routine already is, I decided to cut it down to save time. Now I apply my BHA almost immediately after my Vitamin C, and leave the BHA alone for only as long as it takes for me to get dressed and brush my teeth.

cosrx bha swatch


When discussing the effects of active ingredients, I think it’s important to first note what precisely my expectations were, and what I was intending to treat with the introduction of a BHA. BHAs are great for cleaning pores, preventing acne, treating and preventing blackheads, controlling oil production, and soothing inflammation. I don’t get blackheads, and I don’t get typical acne that can be prevented by unclogging pores. My skin is also not oily, so what exactly am I looking to get out of a BHA product? Well I wanted to keep my pores clean (if only to reduce their appearance, not prevent them from clogging), and I wanted to get whatever anti-inflammatory effect I could to help soothe any of my redness. Since BHAs do exfoliate, I also wanted a more even and smooth skin texture.

On all fronts, this BHA has performed on the lower end of mediocre. That is to say, it seems to not really do a whole lot. As I’ve noted before, topical products are very limited in what they can do to affect my redness, and this one is no different. Redness reduction from any anti-inflammatory effect has been minimal to none. For cleaning my pores, it does okay I guess? What’s fun is that I actually noticed my first blackhead in years while I’ve been using this BHA. Yes, the blackhead was just about microscopic and I probably wouldn’t have noticed it if I didn’t have my nose pressed to a mirror at the time, and I’m certainly not blaming this BHA for causing the blackhead. My skin takes very well to acids (I almost immediately starting using this on a daily basis and experienced almost no effect whatsoever), and I think this gentle BHA is probably too gentle to have much benefit for me.

cosrx bha 2

Would I Repurchase?

I’ll keep using it up, because why not, but I won’t be purchasing more of this one. Due to unfortunate circumstances with Canada’s mail system, I actually have 2 bottles of this to finish. The first one I ordered had taken so long to arrive that I was concerned it was lost, so I went out to a physical K-Beauty store in my city to pick up another to make sure I had one to test by the time it came up in my schedule. Then, predictably, the first one arrived in the mail almost immediately after. Oh well. Hopefully I’ll be finished with them by the time I’m ready to try something different.

I think COSRX’s BHA is probably great for people who are new to acids and need something to start with, or who have sensitive skin that has issues with stronger actives. It’s just too gentle for my skin.

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