COSRX Low ph bha overnight mask
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COSRX Low ph bha overnight mask

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Overview

What it is

Overnight mask with 26 ingredients that contains AHA, BHA, niacinamide and PHA

Cool Features

It is cruelty-free 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, parabens or sulfates

Fun facts

COSRX is from South Korea.

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 (and what isn't)

Key Ingredients

Benefits

Concerns

Ingredients Explained

Skin Conditioning

Centella Asiatica Leaf Water is created by distilling centella asiatica leaves. Centella Asiatica is a herb native to Southeast Asia.

Many active components found in Centella Asiatica Extract, such as Madecassic Acid and Asiaticoside, encourage the skin to naturally produce hyaluronic acid. This helps keep our skin hydrated. Many of these components also show antioxidant activity and may help reduce the signs of aging.

Other components of Centella Asiatic Extract include Vitamin A, vitamin C, several B vitamins, and Asiatic Acid.

Learn more about Centella Asiatica Leaf Water
Humectant, Masking, Skin Conditioning

Butylene Glycol (or BG) is used within cosmetic products for a few different reasons:

Overall, Butylene Glycol is a safe and well-rounded ingredient that works well with other ingredients.

Though this ingredient works well with most skin types, some people with sensitive skin may experience a reaction such as allergic rashes, closed comedones, or itchiness.

Learn more about Butylene Glycol
Emollient, Masking, Skin Conditioning

Helianthus Annuus Seed Oil is the oil derived from the seeds of a Sunflower. Sunflower seed oil is non-fragrant. It is an emollient, meaning it helps to soften the skin.

Sunflower seed oil contains many fatty acids. The fatty acids found in sunflower seeds include (from highest amount to least): linoleic acid, myristic acid, palmitic acid, stearic acid, arachidic acid, oleic acid, and linolenic acid.

These fatty acids help the skin create ceramides. Ceramides play a role in repairing the skin barrier.

Helianthus Annuus Seed Oil helps moisturize the skin. This in turn helps the skin look more rejuvenated and smoother.

Sunflowers are rich in vitamin E.

Historians believe Indigenous cultures of North America domesticated sunflowers before corn. Thus they relied on sunflower oil for a variety of uses. One such use is moisturizing skin and hair.

Sunflower seed oil may not be fungal acne safe. We recommend speaking with a professional if you have any concerns.

Learn more about Helianthus Annuus Seed Oil
Humectant, Skin Conditioning, Skin Protecting

Glycerin is already naturally found in your skin. It helps moisturize and protect your skin.

A study from 2016 found glycerin to be more effective as a humectant than AHAs and hyaluronic acid.

As a humectant, it helps the skin stay hydrated by pulling moisture to your skin. The low molecular weight of glycerin allows it to pull moisture into the deeper layers of your skin.

Hydrated skin improves your skin barrier; Your skin barrier helps protect against irritants and bacteria.

Glycerin has also been found to have antimicrobial and antiviral properties. Due to these properties, glycerin is often used in wound and burn treatments.

In cosmetics, glycerin is usually derived from plants such as soybean or palm. However, it can also be sourced from animals, such as tallow or animal fat.

This ingredient is organic, colorless, odorless, and non-toxic.

Glycerin is the name for this ingredient in American English. British English uses Glycerol/Glycerine.

Learn more about Glycerin
Humectant, Skin Conditioning

Betaine is a common humectant (a substance that promotes retention of moisture). It's known to be gentle on the skin and can help balance hydration.

This ingredient is best for improving hydration and soothing irritated skin. Studies also show it helps even out skin tone.

Fun fact: Betaine is naturally created in the skin and body. The kind found within cosmetic products can be either plant-derived or synthetic.

Learn more about Betaine
Skin Conditioning

Panthenol is a common ingredient that helps hydrate and soothe the skin. It is found naturally in our skin and hair.

There are two forms of panthenol: D and L.

D-panthenol is also known as dexpanthenol. Most cosmetics use dexpanthenol or a mixture of D and L-panthenol.

Panthenol is famous due to its ability to go deeper into the skin's layers. Using this ingredient has numerous pros (and no cons):

Like hyaluronic acid, panthenol is a humectant. Humectants are able to bind and hold large amounts of water to keep skin hydrated.

This ingredient works well for wound healing. It works by increasing tissue in the wound and helps close open wounds.

Once oxidized, panthenol converts to pantothenic acid. Panthothenic acid is found in all living cells.

This ingredient is also referred to as pro-vitamin B5.

Learn more about Panthenol
Emollient, Emulsifying, Emulsion Stabilising

Cetearyl alcohol is a mixture of two fatty alcohols: cetyl alcohol and stearyl alcohol. It is mainly used as an emulsifier. Emulsifiers help prevent the separation of oils and products. Due to its composition, it can also be used to thicken a product or help create foam.

Cetearyl alcohol is an emollient. Emollients help soothe and hydrate the skin by trapping moisture.

Studies show Cetearyl alcohol is non-toxic and non-irritating. The FDA allows products labeled "alcohol-free" to have fatty alcohols.

This ingredient is usually derived from plant oils such as palm, vegetable, or coconut oils. There is debate on whether this ingredient will cause acne.

Due to the fatty acid base, this ingredient may not be Malassezia folliculitis safe.

Learn more about Cetearyl Alcohol
Emollient, Skin Conditioning, Skin Protecting

Dimethicone is a type of synthetic silicone created from natural materials such as quartz.

What it does:

Dimethicone comes in different viscosities:

Depending on the viscosity, dimethicone has different properties.

Ingredients lists don't always show which type is used, so we recommend reaching out to the brand if you have questions about the viscosity.

This ingredient is unlikely to cause irritation because it does not get absorbed into skin. However, people with silicone allergies should be careful about using this ingredient.

Note: Dimethicone may contribute to pilling. This is because it is not oil or water soluble, so pilling may occur when layered with products. When mixed with heavy oils in a formula, the outcome is also quite greasy.

Learn more about Dimethicone

Elaeis Guineensis Oil comes from the African Palm tree. This tree is native to Western and Southwestern Africa.

This oil is rich in antioxidants such as Vitamin E. Antioxidants may help with anti-aging.

The Vitamin E and fatty acid content give palm oil a skin-hydrating property. Emollients help trap moisture in by creating a film on the skin.

Palm oil is created by either squeezing the fruit or crushing the kernel at the center of the fruit. In the 1800s, archaeologists discovered a 6000 year old Egyptian tomb containing palm oil.

Palm oil is controversial due to its social and environmental impacts. Several organizations are working to make palm oil harvest more sustainable, such as the RSPO.

Learn more about Elaeis Guineensis Oil

Elaeis Guineensis Oil comes from the African Palm tree. This tree is native to Western and Southwestern Africa.

The kernel and fruit of the palm tree are often used to create palm oil.

The Vitamin E and fatty acid content give palm oil a skin-hydrating property. Emollients help trap moisture in by creating a film on the skin.

Learn more about Elaeis Guineensis Kernel Oil
Emulsion Stabilising, Masking, Skin Conditioning

Beeswax is natural wax produced by honey bees and can be synthetically created. It consists mainly of fatty acid esters and long-chain alcohols.

In cosmetics, beeswax is a emollient. Due to its waxy structure, it creates a protective barrier. This barrier prevents water from evaporating off the skin.

This may not be a good ingredient for oily skin. We recommend speaking with a professional if you have concerns.

Beeswax cannot be removed with water, but can be taken off with an oil cleanser.

Beeswax is also antiseptic and contains vitamin A.

Learn more about Beeswax
Skin Conditioning

Gluconolactone is a PHA. PHAs are a great gentle alternative to traditional AHAs.

When applied, Gluconolactone has the same affect on skin as AHAs such as lactic acid. It helps dissolve the dead skin cells in the top layer of your skin. This improves texture and brightens the skin.

PHAs are more gentle than AHAs due to their larger structure. They do not penetrate as deeply as AHAs and take a longer time to dissolve dead cells. Studies show PHAs do not cause as much irritation.

Gluconolactone has some interesting properties:

In a 2004 study, Gluconolactone was found to prevent UV damage in mouse skin cells and has not been found to increase sun sensitivity. However, we still recommend wearing SPF daily.

This ingredient is is an created by reacting gluconic acid with an alcohol.

Learn more about Gluconolactone

This is a synthetic polymer. It helps improve the texture of products by adding thickness and gel-like feel.

It is also an emulsifer, meaning it prevents ingredients such as oil and water from separating. It also helps evenly disperse other ingredients.

Cetearyl Olivate is an emulsifier and texture enhancer. It is derived from the fatty acids of olive oil and Cetearyl alcohol, and is biodegradable.

As an emulsifier, it is used to prevent oils and waters from separating. It can also

Manufacturers use the name Olivem 1000. This ingredient has been found to preserve the natural microbiome of skin. Having a healthy microbiome helps keep our skin healthy and protects against harmful bacteria. This ingredient is grouped with Sorbitan Olivate under the name Olivem 1000.

Learn more about Cetearyl Olivate
Emulsifying

Sorbitan Olivate is created from the fatty acids in olive oil and sorbitol.

This ingredient is an oil in water emulsifier. It helps stabilize a product by preventing oils and waters from separating. Sorbitan Olivate also helps hydrate the skin.

Manufacturers sell sorbitan olivate under the name OliveM 1000. OliveM 1000 a multifunctional ingredient. It is self-emulsifying. According to a manufacturer, OliveM 1000 does not disrupt natural skin biome.

Due to its olive oil base, this ingredient may not be fungal-acne safe.

Learn more about Sorbitan Olivate
Masking, Skin Conditioning

This ingredient is an emollient, solvent, and texture enhancer. It is considered a skin-softener by helping the skin prevent moisture loss.

It helps thicken a product's formula and makes it easier to spread by dissolving clumping compounds.

Caprylic Triglyceride is made by combining glycerin with coconut oil, forming a clear liquid.

While there is an assumption Caprylic Triglyceride can clog pores due to it being derived from coconut oil, there is no research supporting this.

Learn more about Caprylic/Capric Triglyceride
Skin Conditioning, Solvent

1,2-Hexanediol is a synthetic liquid and another multi-functional powerhouse. 

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 preservatives 
Antimicrobial

Betaine Salicylate is considered a salicylic acid alternative.

Limited studies exist proving this ingredient to be a complete alternative to salicylic acid. Based on existing research, this ingredient does not penetrate as deeply and is not shown to be as effective.

However, this makes it a great choice for those with sensitive skin or need gentle BHA action.

This ingredient is created using betaine and salicylic acid.

This ingredient is oil-soluble and is most effective at a pH range of 3.8-4.2.

Learn more about Betaine Salicylate
Skin Conditioning

Ethylhexylglycerin (we can't pronounce this either) is commonly used as a preservative and skin softener. It is derived from glyceryl.

You might see Ethylhexylglycerin often paired with other preservatives such as phenoxyethanol. Ethylhexylglycerin has been found to increase the effectiveness of these other preservatives.

Buffering, Humectant, Skin Conditioning

Lactic Acid is an AHA that is derived from fermenting lactose, a carbohydrate from milk. It removes the top layer of old and dead skin cells and helps increase cell turnover.

Benefits of Lactic Acid are that it can help to reduce large pores and reduce the effects of aging. Some potential downsides are that it can be bad for dry skin, cause irritation, worsen eczema, and worsen rosacea.

Not only does it help exfoliate the skin, it helps strengthen the skin's barrier. When applied, lactic acid helps the skin create ceramides.

Lactic acid is an over-the-counter chemical exfoliant that comes from the fermentation of lactose — a carbohydrate found in milk.

Legend has it that Cleopatra used to bathe in sour milk to help reduce wrinkles.

Read more about some other popular AHA's here:

Learn more about Lactic Acid
Skin Conditioning, Solvent

Water. It's the most common cosmetic ingredient of all. You'll usually see it at the top of ingredient lists, meaning that it makes up the largest part of the product.

So why is it so popular? Water most often acts as a solvent - this means that it helps dissolve other ingredients into the formulation.

You'll also recognize water as that liquid we all need to stay alive. If you see this, drink a glass of water. Stay hydrated!

Learn more about Water
Smoothing

Niacinamide 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 Niacinamide
Emulsifying, Emulsion Stabilising, Gel Forming

Xanthan gum is used as a stabilizer and thickener within cosmetic products. It helps give products a sticky, thick feeling - preventing them from being too runny.

On the technical side of things, xanthan gum is a polysaccharide - a combination consisting of multiple sugar molecules bonded together.

Xanthan gum is a pretty common and great ingredient. It is a natural, non-toxic, non-irritating ingredient that is also commonly used in food products.

Learn more about Xanthan Gum
Buffering

Sodium Hydroxide is also known as lye or caustic soda. It is used to adjust the pH of products; many ingredients require a specific pH to be effective.

In small amounts, sodium hydroxide is considered safe to use. However, large amounts may cause chemical burns due to its high alkaline.

Your skin has a natural pH and acid mantle. This acid mantle helps prevent harmful bacteria from breaking through. The acid mantle also helps keep your skin hydrated.

"Alkaline" refers to a high pH level. A low pH level would be considered acidic.

Learn more about Sodium Hydroxide

Ethyl Hexanediol is an aliphatic alcohol. It is a solvent.

Solvents are used to keep ingredients together in a product. They can help dissolve ingredients to stable bases or help evenly distribute ingredients throughout the product.

Antioxidant, Perfuming

This tea tree oil comes from the leaves of the Tea Tree plant. Tea tree oil has antioxidant, anti-inflammatory, and antimicrobial properties.

According to the book Journal of Profiles of Drug Substances, tea tree helps in reducing acne-causing bacteria such as Propionibacterium acnes. This is due to the Terpinen components of tea tree oil.

Tea tree may cause sensitivity and irritation for some people. This oil naturally contains fragrance such as linalool and limonene.

However, research shows irritation usually occurs when using pure tea tree oil and not in cosmetic products.

Tea tree oil was found to help relieve the symptoms of psoriasis in one study.

Tea tree oil is toxic when ingested. Another study showed it to caused damage to the nervous system of dogs and cats when applied to their skin or given orally.

Learn more about Melaleuca Alternifolia Leaf Oil

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· Published May 28, 2025 Added by allisonedwards