Cos De BAHA 2% Hydroquinone + Arbutin + Niacinamide 4% Serum
A highly rated serum with 18 ingredients, including BHA, niacinamide, and hyaluronic acid.
Overview
What it is
Serum with 18 ingredients that contains arbutin, BHA, hyaluronic acid, kojic acid and niacinamide
Cool Features
It is cruelty-free, fungal acne (malassezia) safe, and reef safe
Suited For
It has ingredients that are good for fighting acne, anti aging, dry skin, brightening skin, sensitive skin, oily skin, reducing pores, scar healing, dark spots and better texture
Free From
It doesn't contain any harsh alcohols, common allergens, oils, parabens, silicones or sulfates
Fun facts
Cos De BAHA is from South Korea. This product is used in 129 routines created by our community.
We independently verify ingredients and our claims are backed by peer-reviewed research. Does this product need an update? Let us know.
What's inside
Ingredients List
Aloe Barbadensis Leaf Extract
EmollientPropanediol
SolventArbutin
AntioxidantNiacinamide
Smoothing1,2-Hexanediol
Skin ConditioningHydroquinone
StabilisingCitric Acid
BufferingSodium Citrate
BufferingSodium Hyaluronate
HumectantSalicylic Acid
MaskingKojic Acid
AntioxidantLactic Acid
BufferingHamamelis Virginiana Leaf Extract
Skin ConditioningRosmarinus Officinalis Extract
AntimicrobialEucalyptus Globulus Leaf
Skin ConditioningThymus Vulgaris Extract
PerfumingAspalathus Linearis Extract
Skin ConditioningDisodium EDTA
Aloe Barbadensis Leaf Extract, Propanediol, Arbutin, Niacinamide, 1,2-Hexanediol, Hydroquinone, Citric Acid, Sodium Citrate, Sodium Hyaluronate, Salicylic Acid, Kojic Acid, Lactic Acid, Hamamelis Virginiana Leaf Extract, Rosmarinus Officinalis Extract, Eucalyptus Globulus Leaf, Thymus Vulgaris Extract, Aspalathus Linearis Extract, Disodium EDTA
Key Ingredients
Benefits
Concerns
Ingredients Explained
Aloe Barbadensis Leaf Extract is an extract of the leaves of the aloe, Aloe barbadensis, Liliaceae.
Aloe is one of the most well-known natural soothing ingredients, and for good reason. Itâs full of water and has a cooling, calming effect on the skin, especially when itâs sunburned, itchy, or irritated. Aloe also helps your skin stay hydrated and smooth by mimicking what healthy skin naturally produces. On top of that, it contains vitamins and nutrients that support skin recovery.Â
It doesnât protect you from the sun, but it can help your skin bounce back after too much time in it.
Letâs get into the details:
Aloe contains antioxidant Vitamins A, C, and E, which help fight off free radicals (unstable molecules from things like pollution that can damage your skin).
Itâs also rich in polysaccharides, which are natural sugars that help hydrate the skin by acting like the skinâs own moisturizing agents. These, along with other sugars like monosaccharides, help form a protective barrier that locks in moisture.
Aloe works as both a humectant and an emollient. That means it draws water into the skin (humectant) and helps trap it there (emollient), making it an effective natural moisturizer.
Youâll also find a mix of other skin-supporting ingredients in aloe, including folic acid, choline, calcium, amino acids, fatty acids, and even Vitamin B12.
Out of the 420+ species of aloe, Aloe barbadensis is the most widely used in skincare products thanks to its gentle yet effective properties.
There are over 420 species of aloe but Aloe Barbadensis is the most commonly used for topical products.
Learn more about Aloe Barbadensis Leaf ExtractPropanediol is an all-star ingredient. It softens, hydrates, and smooths the skin.Â
Itâs often used to:
Propanediol is not likely to cause sensitivity and considered safe to use. It is derived from corn or petroleum with a clear color and no scent.
Learn more about PropanediolArbutin is derived from the bearberry plant. It helps even out skin tone and reduce hyperpigmentation.
This ingredient has the ability to block tyrosinase, an enzyme that starts the process of skin darkening. When applied to the skin, arbutin works at a slow pace. This can make it less irritating than similar ingredients.
Kojic Acid is a similar ingredient.
Learn more about ArbutinNiacinamide is a multitasking form of vitamin B3 that strengthens the skin barrier, reduces pores and dark spots, regulates oil, and improves signs of aging.
And the best part? It's gentle and well-tolerated by most skin types, including sensitive and reactive skin.
You might have heard of "niacin flush", or the reddening of skin that causes itchiness. Niacinamide has not been found to cause this.
In very rare cases, some individuals may not be able to tolerate niacinamide at all or experience an allergic reaction to it.
If you are experiencing flaking, irritation, and dryness with this ingredient, be sure to double check all your products as this ingredient can be found in all categories of skincare.
When incorporating niacinamide into your routine, look out for concentration amounts. Typically, 5% niacinamide provides benefits such as fading dark spots. However, if you have sensitive skin, it is better to begin with a smaller concentration.
When you apply niacinamide to your skin, your body converts it into nicotinamide adenine dinucleotide (NAD). NAD is an essential coenzyme that is already found in your cells as "fuel" and powers countless biological processes.
In your skin, NAD helps repair cell damage, produce new healthy cells, support collagen production, strengthen the skin barrier, and fight environmental stressors (like UV and pollution).
Our natural NAD levels start to decline with age, leading to slower skin repair, visible aging, and a weaker skin barrier. By providing your skin niacinamide, you're recharging your skin's NAD levels. This leads to stronger, healthier, and younger looking skin.
Another name for vitamin B3 is nicotinamide. This vitamin is water-soluble and our bodies don't store it. We obtain Vitamin B3 from either food or skincare. Meat, fish, wheat, yeast, and leafy greens contain vitamin B3.
The type of niacinamide used in skincare is synthetically created.
Learn more about Niacinamide1,2-Hexanediol is a synthetic liquid and another multi-functional powerhouse.Â
It is a:
- Humectant, drawing moisture into the skin
- Emollient, helping to soften skin
- Solvent, dispersing and stabilizing formulas
- Preservative booster, enhancing the antimicrobial activity of other preservativesÂ
Hydroquinone is a classic ingredient dermatologists use to fade dark spots (things like melasma, acne marks, sun spots, and freckles).
It works in two ways:
1. By blocking an enzyme called tyrosinase; your skin uses this to make melanin, or the pigment that causes dark spots.
2. By interfering with the pigment making cells themselves so less pigment shows up over time
Just know this ingredient fades spots near the surface of skin and not the deeper ones. It's usually used at 2-4% / twice a day for 3 months, and ALWAYS with sunscreen.
This ingredient is usually well tolerated with short-term use under medical guidance. But possible reactions include irritation, contact dermatitis, and lightening of the skin around the spot you're treating.
You might hear hydroquinone called "cancer-causing". That concern comes from studies where rats were fed high oral doses; no skin cancer cases have been linked to it after more than 50 years of people putting it on their skin.
Long-term, high-strength, and unsupervised use can lead to a condition called ochronosis. This is where the skin turns blue-grey color and sometimes causes nails to turn dark as well.
The rules around it vary by country.
The EU bans it in regular cosmetics and it is prescription only in the US, EU, Japan, Canada, and Australia. Anything you see on the shelf without a prescription is technically not allowed.
Check out the European alternative to hydroquinone here.
SkinSort would like to remind friends from around the world that all skin tones are beautiful!
Learn more about HydroquinoneCitric Acid is an alpha hydroxy acid (AHA) naturally found in citrus fruits like oranges, lemons, and limes.
Like other AHAs, citric acid can exfoliate skin by breaking down the bonds that hold dead skin cells together. This helps reveal smoother and brighter skin underneath.
However, this exfoliating effect only happens at high concentrations (20%) which can be hard to find in cosmetic products.
Due to this, citric acid is usually included in small amounts as a pH adjuster. This helps keep products slightly more acidic and compatible with skin's natural pH.
In skincare formulas, citric acid can:
While it can provide some skin benefits, research shows lactic acid and glycolic acid are generally more effective and less irritating exfoliants.
Most citric acid used in skincare today is made by fermenting sugars (usually from molasses). This synthetic version is identical to the natural citrus form but easier to stabilize and use in formulations.
Read more about some other popular AHA's here:
Learn more about Citric AcidSodium Citrate is the sodium salts of citric acid. In skincare, it is used to alter pH levels and acts as a preservative.
Its main functions are to maintain the pH of a product and neutralize metal ions.
The acidity of our skin is maintained by our glands and skin biome; normal pH level of skin is slightly acidic (~4.75-5.5).
Being slightly acidic allows our skin to create an "acid mantle". This acid mantle is a thin barrier that protects our skin from bacteria and contaminants.
Learn more about Sodium CitrateSodium Hyaluronate is the salt form of hyaluronic acid. It is a long sugar chain that is naturally found in your skin, joints, and connective tissue that maintains hydration and elasticity.
In skincare, it works as a humectant. It pulls water from the environment and deeper layers of skin and binds it to the surface.
Interestingly, the size of the molecule affects its behavior:
Some clinical evidence links low molecular weight versions to improved wrinkle depth, elasticity, anti-inflammatory effects, and barrier repair.
Many serums use a blend of both weights so you can get surface hydration plus longer-lasting and deeper effects.
You'll typically see concentrations between 0.1-2% for this ingredient.
Learn more about Sodium HyaluronateSalicylic Acid (also known as beta hydroxy acid or BHA) is a well-known ingredient for treating skin that struggles with acne and clogged pores. It exfoliates both the skin's surface and deep within the pores to help clear out buildup, control oil, and reduce inflammation.
Unlike AHAs (alpha hydroxy acids), salicylic acid is oil-soluble. This allows it to penetrate into pores which makes it especially effective for treating blackheads and preventing future breakouts.
Salicylic acid is also known for its soothing properties. It has a similar structure to aspirin and can calm inflamed or irritated skin, making it a good option for acne-prone skin that is also sensitive.
Concentrations of 0.5-2% are recognized by the U.S. FDA as an over-the-counter topical acne product.
It can cause irritation and/or dryness if one's skin already has a compromised moisture barrier, so it's best to focus on repairing that before introducing this ingredient into your routine.
While salicylic acid does not increase sun sensitivity, itâs still important to wear sunscreen daily to protect your skin.
If you are looking for the ingredient called BHA or Butylated Hydroxyanisole, click here.
Learn more about Salicylic AcidKojic Acid is a naturally occurring organic acid that is produced during the fermentation of certain fungi. It is one of the most well-studied brightening ingredients (tyrosinase inhibitors) out there.
That's why you'll see Kojic Acid in products that target dark spots, hyperpigmentation, and general uneven skin tone. It also pairs well with other brightening actives like Alpha Arbutin, Glycolic Acid, and Vitamin C derivatives.
By latching onto the copper that the enzyme tyrosinase needs to function, Kojic Acid prevents less pigment from being made. It's so well-established that researchers regularly use it as the go-to benchmark when testing new brightening ingredients.
Some other perks include documented antioxidant and antimicrobial properties. The The CIR (Cosmetic Ingredient Review) Expert Panel concluded Kojic Acid is safe for use in cosmetic products at concentrations up to 1% and the EU's SCCS (Scientific Committee on Consumer Safety) considers it safe as a skin lightening agent at concentrations up to 0.7%.
One thing to know about Kojic Acid is that stability is its weak spot; it is sensitive to light, heat, and air exposure and will oxidize/turn brown in formulations. Its derivative, Kojic Dipalmitate, was developed as a stable alternative.
Some individuals have reported contact sensitization so be sure to patch test if you have reactive or sensitive skin.
Fun fact: It was first discovered in 1907 and naturally occurs in the production of sake, soy sauce, and miso.
Learn more about Kojic AcidLactic Acid is another well-loved alpha hydroxy acid (AHA). It is gentler than glycolic acid but still highly effective.
Its main role is to exfoliate the surface of the skin by loosening the âglueâ that holds dead skin cells together. Shedding those old cells leads to smoother, softer, and more even-toned skin.
Because lactic acid molecules are larger than glycolic acid, they donât penetrate as deeply. This means theyâre less likely to sting or irritate, making it a great choice for beginners or those with sensitive skin.
Like glycolic acid, it can:
Lactic acid also acts as a humectant (like hyaluronic acid). It can draw water into the skin to improve hydration and also plays a role in the skin's natural moisturizing factor (NMF) in the form of sodium lactate.
Studies show it can boost ceramide production to strengthen the skin barrier and even help balance the skinâs microbiome.
To get results, choose products with a pH between 3-4.
Lower strengths (5-12%) focus on surface exfoliation; higher strengths (12% and up) can reach deeper in the dermis (deeper, supportive layer) to improve skin texture and firmness over time.
Though it was originally derived from milk, most modern lactic acid used in skincare is vegan. It is made through non-dairy fermentation to create a bio-identical and stable form suitable for all formulations.
When lactic acid shows up near the end of an ingredient list, it usually means the brand added just a tiny amount to adjust the productâs pH.
Legend has it that Cleopatra used to bathe in sour milk to help reduce wrinkles.
Lactic acid is truly a gentle multitasker: it exfoliates, hydrates, strengthens, and brightens. It's a great ingredient for giving your skin a smooth, glowing, and healthy look without the harshness of stronger acids.
Read more about some other popular AHA's here:
Learn more about Lactic AcidHamamelis Virginiana Leaf Extract comes from the witch hazel plant.
Witch Hazel is an astringent, anti-inflammatory, antioxidant, and antibacterial ingredient.
The tannin in witch hazel has a drying effect when used on skin and constricts proteins. This helps minimize the look of large pores. The presence of tannins and fragrance may be sensitizing.
The catechins in witch hazel have anti-inflammatory properties while the gallic acid is antibacterial.
Indigenous groups have used witch hazel to help treat inflammation, which was then used by early settlers to North America.
Learn more about Hamamelis Virginiana Leaf ExtractRosemary extract has antioxidant, anti-inflammatory, anti-bacterial, and astringent properties.
This ingredient has a natural fragrance due its small component of rosemary oil. The antioxidant properties from its rosmarinic acid, flavone, and phenolic acids.
We don't have a description for Eucalyptus Globulus Leaf yet.
This ingredient comes form the common thyme plant. It has skin conditioning and perfuming ingredients.
In-vitro studies show strong antioxidant activity due to the high phenolic content of thyme.
Studies also demonstrate it has antimicrobial activity against acne-related bacteria. A 2017 study found this extract exhibited anti-inflammatory effects.
However, this ingredient does have sensitization potential due to its terpene content. Terpenes are among the most common causes of contact dermatitis.
This is kind of a double-edged sword situation where the same compounds that give it antimicrobial power can also irritate reactive skin.
Learn more about Thymus Vulgaris ExtractThis ingredient is also known as Rooibos. It is a caffeine-free plant rich in antioxidants such as vitamin C and polyphenols.
Disodium EDTA is a chelating agent. It grabs onto and deactivates metal ions that sneak into your products from water, packaging, or air.
This ingredient mainly works behind the scenes and helps with:
On top of that, this ingredient can counteract the effects of hard water by binding to the minerals in it.
One thing worth knowing is that Disodium EDTA has been shown to be a mild penetration enhancer. It can help other ingredients absorb into skin more effectively which can be a double-edged sword (great for actives, but can also make the active too strong if you have sensitive skin).
Clinical patch testing showed no significant skin irritation at typical use concentrations and minimal dermal absorption.
You'll most likely see this ingredient near the end of an ingredient list. It's typically found in concentrations less than 1%.
Learn more about Disodium EDTAReviews
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Where it's from
Cos De BAHA is a Korean brand
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The data we've presented on this page has been verified by a member of the SkinSort Team.
Read more about us· Updated August 20, 2025 • Added by hyggeday