Kolai Enzyme Peel Anti-Age Enzyme Peel Face Mask

Your skin makes glycerin on its own (mostly from sebaceous oil breakdown) and shuttles it to your outermost layer of skin, or your epidermis, via aquaporin-3.

Aquaporin-3 is a transporter that is essential for normal skin hydration, elasticity, and repair. Interestingly, mice lacking in AQP3 have dry and less elastic skin that can be fully corrected with glycerin.

This ingredient is non-irritating, plays well with almost every ingredient, and works across all skin types. Typical use is anywhere between 3-10% but can go up to 79% in some leave-on products.

Just know very high concentrations (>40%) can feel tacky in low humidity.

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

Though it has "alcohol" in the name, it is not related to denatured alcohol or ethyl alcohol.

The FDA allows products labeled "alcohol-free" to have fatty alcohols.

This ingredient may not be fungal acne safe. It is a primary fatty alcohol with a chain length above 12 carbons. A study from 2019 show Malassezia can feed on fatty alcohols in this range, so it may trigger fungal acne in those prone to it.

Emollients help your skin stay smooth and soft. It does so by creating a film on top of the skin that helps trap moisture in.

A double-blind study confirmed that extra virgin coconut oil is as effective as mineral oil for treating very dry skin. Another study found it outperformed mineral oil for mild to moderate atopic dermatitis in children.

Another study from 2018 found that virgin coconut oil can soothe inflammation and boost key skin barrier proteins. Just know this evidence is still only from lab settings and not human trials.

It has also been shown to reduce Staphylococcus aureus, a bacteria that commonly overgrows in people with eczema.

Clinical testing shows very minimal skin irritation and no evidence of sensitization or phototoxicity.

Coconut oil gets flagged as a "fragrance" because it has a natural mild scent (not because it's a synthetic perfume). The European Cosmetic ingredient database also lists "perfuming" as a function of this ingredient.

Just so you know, the term "fragrance" is completely unregulated. Some brands still use botanical extracts or essential oils in their "fragrance-free" formulas, but regulatory databases technically classify these under "fragrance".

Coconut oil has a tiny and useless bit of natural SPF. Early lab studies clocked it around SPF 7-8 but a more recent study found the real number closer to SPF 1.2. It also offers no meaningful UVA protection (SPF only overs UVB rays).

The comedogenic rating of 4/5 means it has a high potential to clog pores; but it's worth noting that comedogenicity is highly individual and ratings cannot predict how an overall formula will behave on skin.

Since lauric acid is the dominant fatty acid, this ingredient may not be fungal acne safe. The Malassezia yeast feeds on fatty acids with carbon chain lengths between 11-24, and lauric acid falls within these lengths (C12).

Unlike other exfoliants, papain can work without causing significant irritation.

Beyond exfoliation, its proteolytic action also helps soothe irritated skin and supports the healing of minor wounds.

A 2024 in vivo/in vitro study confirmed its potential to suppress skin inflammation and improve transepidermal water loss (TEWL) in atopic dermatitis models.

Just one thing worth noting: there are reports of allergic responses in individuals with a papaya or latex sensitivity. Be sure to patch test if you're in this camp.

In vitro research found an increase in skin hydration by 58% and a decrease in TEWL by 37.8% after 24 hours of applying this ingredient (pretty impressive for a single ingredient!).

Besides hydration, shea butter also contains triterpenes that have anti-inflammatory potential. In particule, lupeol cinnamate has shown the highest anti-inflammatory activity in vivo.

Shea butter also contains vitamins A and E which may contribute to antioxidant activity.

While Shea Butter has an SPF rating of about 3-4, it is not a sunscreen replacement.

This ingredient may not be fungal acne safe because its fatty acids fall within the C11-C24 range that the Malassezia yeast can metabolize.

Typical use ranges from 0.5-30%. Most leave-on products are in the 1-10% zone.

The 20 ethylene oxide units is well above the PEG-10 threshold and therefore not a food source for Malassezia (it's fungal acne safe).

This ingredient has a comedogenic rating of 2 and an irritancy rating of 3. These numbers come from testing the raw ingredient on rabbit ears and doesn't reflect how it will behave in a finished product.

In practice, this ingredient is a well-tolerated ingredient. The ratings reflect cautious lab conditions and not real-world use. Just be sure to patch test any formulas you feel unsure about.

The CIR Expert Panel has confirmed this ingredient to be nontoxic and clinical studies show no sensitization at cosmetic use concentrations.

True allergic reactions are quite rare: a 15-year retrospective study of 6,751 patients found only 0.31% had a positive reaction (and less than half were considered clinically relevant).

It seemed that when sensitization does occur, it's most commonly linked to topical medication (like corticosteroids) and not cosmetics. Allergic contact dermatitis also appears largely limited to individuals with underlying skin conditions.

Overall, propylene glycol is a well-studied ingredient that most people can tolerate without issue.

This ingredient is generally considered non-toxic, non-irritating, and has low absorption potential.

You might have heard that this ingredient clogs pores. This reputation comes from the older rabbit ear studies which are more sensitive than human skin to clogging.

Dermatologist Dr. Zoe Draelos has also confirmed in a peer-reviewed paper that products containing comedogenic ingredients are not necessarily comedogenic themselves.

A small subset of people (~2%) may experience contact sensitivity so patch testing is a reasonable idea if you have reactive skin.

Since this ingredient is an ester of myristic acid (a C14 fatty acid), it falls within the carbon chain range that is known to feed Malassezia. This ingredient may not be fungal acne safe.

Here's an interesting thing about Arginine: your skin converts it into urea through the Krebs-Henseleit urea cycle. Urea is one of the most effective humectants your skin naturally produces.

A clinical study showed applying 2.5% arginine hydrochloride to atopic dermatitis skin showed significant urea levels in the stratum corneum and improved moisture in just four weeks.

Arginine is also a precursor to nitric oxide; nitric oxide improves microcirculation and supports wound healing and collagen synthesis.

One study found that an amino acid complex containing Arginine reduced skin irritation, improved hydration, and accelerated skin repair in clinical / in-vivo studies.

Arginine itself is an amino acid and not a fatty acid, oil, or ester. On its own, it's not a direct food source for Malassezia, or the yeast that causes fungal acne.

Two clinical studies in postmenopausal women found that applying argan oil for 60 days significantly improved skin elasticity and moisturization (reduced transepidermal water loss and increased epidermal water content).

Since it is high in oleic and linoleic acid, this ingredient may not be fungal acne safe. Both of these fall in the C11-C24 range that Malassezia yeast can metabolize.

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, it’s still important to wear sunscreen daily to protect your skin.

If you are looking for the ingredient called BHA or Butylated Hydroxyanisole, click here.

Urea has the strongest exfoliation effect in concentrations higher than 10%. It is a keratolytic agent, meaning it breaks down the keratin protein in the top layer of skin. This helps remove dead skin cells and flaking skin.

In medicine, urea has been shown to help increase the potency of other ingredients, such as fungal treatments.

Humans and animals use urea to metabolize nitrogen-containing compounds. Urea is highly soluble in water. Once dissolved, it is neither acidic nor alkaline.

Urea is actually one of the more well-studied and well-supported ingredients out there if you have eczema.

Clinical trials have shown that urea creams in the 5 - 10% range can:

Higher concentrations (20 -30%) can also help with thickened, scaly patches but is also more likely to sting on active flares.

Skip urea if you have rosacea. The AAD (American Academy of Dermatology) lists it alongside alcohol, menthol, and fragrance as a potential irritant for rosacea-prone skin. Urea's keratolytic and penetration-enhancing properties can trigger stinging, burning, and redness.

As always, your skin is unique, so definitely check in with your dermatologist.

Tocopheryl Acetate is commonly found in both skincare and dietary supplements.

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.

It’s typically used at 0.5-5% concentration, either for mild exfoliation or to improve overall skin health and texture.

Some studies show that Bacillus species can inhibit certain plant fungi (such as Fusarium verticillioides and Fusarium oxysporum) used in agricultural biocontrol. However, these are filamentous molds, not the yeast (Malassezia furfur) responsible for fungal acne.

At this time, there are no studies showing that Bacillus Ferment inhibits Malassezia or that it has been tested on human skin or in cosmetic formulations. Because of this lack of cosmetic and dermatological research, we list Bacillus Ferment as not safe for fungal acne as a precaution. However, it may not trigger breakouts for everyone.

Aloe Barbadensis Leaf Juice also contains sugars. These sugars come in the form of monosaccharides and polysaccharides, folic acid, and choline. These sugars are able to help bind moisture to skin.

It also contains minerals such as calcium, 12 anthraquinones, fatty acids, amino acids, and Vitamin B12.

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.

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.

It should be noted the precursor to Polyacrylamide is acrylamide. Acrylamide is a carcinogen. Most reputable sources of Polyacrylamide will screen for residual acrylamide to make sure the count is in a safe range. Acrylamide is not able to be absorbed through the skin.

We recommend speaking with a professional if you have concerns.

A high amount of carbomer can cause pilling or balling up of products. Don't worry, most products contain 1% or less of carbomer.

Two things floating around online that cause fear-mongering:

There's one scary-sounding study related to kidney tumors in male rats; this depends on a protein called alpha-2u-globulin that binds the ingredient and clogs up kidney cells. Female rats barely make this protein, and humans don't make it at all so this effect cannot happen to us. Regulatory bodies have states this rat-only pathway shouldn't be used to judge human risk.

The other thing you'll see is 1,4-dioxane being a trace byproduct that can form during manufacturing of petroleum-derived ingredients. This is a real, but heavily managed/monitored issue. This byproduct is removed through purification steps before the ingredients goes into the formula. Regulatory bodies also actively monitor residual levels for safety.

One last thing to note: this ingredient is a pure hydrocarbon with no fatty-acid or ester chains for Malassezia to feed on, so it's considered fungal acne safe.

Industry-reported use ranges from 8% in rinse-off products and 2% in leave-on formulations.

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:

Both potassium sorbate and sorbic acid can be found in baked goods, cheeses, dried meats, dried fruit, ice cream, pickles, wine, yogurt, and more.

You'll often find this ingredient used with other preservatives.

Is it bad for your skin?

The answer comes down to concentration. Patch and wash studies have found highly concentrated alcohol-based hand rubs (60-100%) cause less barrier disruption than washing with a basic detergent like SLS. The only measurable effect in these studies was a temporary dip in skin hydration.

Concentrations below 12-15% in leave-on cosmetics is generally well-tolerated. Concentrations above start to see increased transepidermal water loss (TEWL) and reduced hydration.

In concentrations about 58%, it creates temporary channels in your skin's lipid layers to become more permeable and allow other ingredients to slip through easily.

This ingredient can be up to 80% of the formula in alcohol-based perfumes.

Overall, this ingredient is probably harmless if found lower down an ingredients list but worth side-eyeing if it's high up (especially if your barrier is already struggling).

Alcohol can worsen dry skin, eczema, and oily skin, especially at higher concentrations. This is because it can increase transepidermal water loss and decrease hydration to disrupt the skin barrier.

According to the National Rosacea Society based in the US, you should be mindful of products with these alcohols in the top half of ingredients.

True allergic contact dermatitis to ethanol is uncommon, but be sure to patch test if you have dry or sensitive skin.

Sodium benzoate works as a preservative by inhibiting the growth of bacteria inside of cells. It prevents the cell from fermenting a type of sugar using an enzyme called phosphofructokinase.

It is the salt of benzoic acid. Foods containing sodium benzoate include soda, salad dressings, condiments, fruit juices, wines, and snack foods.

Studies for using ascorbic acid and sodium benzoate in cosmetics are lacking, especially in skincare routines with multiple steps.

We always recommend speaking with a professional, such as a dermatologist, if you have any concerns.