Hada Labo Shirojyun Ultimate Whitening Milk

It is also an emollient and helps condition the skin.

Typical usage concentrations range from 1-5%.

Human testing shows it's non-irritating and non-sensitizing, and the EU Scientific Committee on Consumer Safety (SCCS) has cleared it at very high levels (79% in leave-on products).

The one thing worth knowing about its comedogenic score of 3-4 is to keep it in perspective: these ratings come from old rabbit-ear tests using 100% of pure ingredient and doesn't reflect how it behaves at low levels in a finished product.

Because it is an ester of palmitic acid (C16), it falls into the range that the Malassezia yeast can feed on and is considered not fungal acne safe.

Kojic Acid is a similar ingredient.

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.

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.

This property also makes Pentylene Glycol a great texture enhancer. It can also help thicken or stabilize a product.

Pentylene Glycol also acts as a mild preservative and helps to keep a product microbe-free.

Some people may experience mild eye and skin irritation from Pentylene Glycol. We always recommend speaking with a professional about using this ingredient in your routine.

Pentylene Glycol has a low molecular weight and is part of the 1,2-glycol family.

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.

This combination is not really found in any other plant oil and is the reason this is one of the most stable botanical oils available.

Some studies show it to be more stable than jojoba oil, helps a product resist going rancid, and can help extend the shelf life of a formula.

It also naturally contains vitamin E and phytosterols that give it a mild antioxidant benefit.

This ingredient is typically used from around 1% to fairly high levels since it's gentle; it's well-tolerated and low on the irritation scale.

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.

This is also one of the most heavily studied preservatives out there and major regulatory bodies have repeatedly given it the green light.

In 2023, the EU's Scientific Committee on Consumer Safety (SCCS) confirmed that this ingredient is safe up to 0.4% on its own, of up to 0.8% when mixed with other paraben esters.

Here's the science behind the noise behind parabens/hormones as well:

Methylparaben shows very weak estrogen-like activity in vitro tests (more than 1,000x weaker than your body's own estradiol). In vivo (live-organism) studies don't support a meaningful endocrine-disrupting effect either.

You get a stronger estrogenic effect from eating tofu, actually.

It's also a low sensitizer and allergic reactions are uncommon; they usually happen on damage or broken skin.

There is a caveat: France has proposed to formally re-examine its endocrine classification in 2025 so the regulatory conversation isn't fully closed as of yet.

But as it stands today, this ingredient is considered safe at permitted levels.

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%.

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

PH adjusters are common in cosmetic products. The pH of a product can affect the effectiveness of other ingredients. A product with a high pH may also irritate the skin.

If you are looking for the tea leaf ingredient, click here.

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.

While MAP is gentler on the skin than ascorbic acid, it is thought to be less easily absorbed into the skin.

In a well-known absorption study, pure vitamin C increased skin vitamin C levels when formulated correctly, but derivatives like MAP did not in that experiment. This suggests MAP may not always convert into active vitamin C in the skin.

Due to MAP's stability up to a pH level of 7, it is more stable to air and sunlight exposure than ascorbic acid. The best pH range for MAP is between 5 and 6.