COSRX Poreless Pad

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.

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.

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.

Mandelic acid helps with:

Due to it having a larger molecular size than glycolic acid, mandelic acid is able to penetrate the skin more slowly and evenly. This makes it gentler and less irritating, making it a great option for sensitive or beginner skin.

Despite being milder, mandelic acid is still an effective exfoliant that improves skin texture and tone over time.

What makes mandelic acid stand out from other AHAs? It has antibacterial and antioxidant properties.

These traits make it a great option for acne-prone or problem skin by reducing active breakouts and fading post-acne marks. Studies show that mandelic acid (especially when combined with salicylic acid) can significantly reduce pimples and hyperpigmentation while causing fewer side effects than stronger acids.

Mandelic acid is effective in concentrations of 5% and up with an ideal pH range of 3-4 for at-home use.

Like other AHAs, it’s important to wear sunscreen daily to protect your newly exfoliated skin.

However, unlike glycolic acid, mandelic acid is light-sensitive. Be sure your mandelic acid is packaged in opaque containers to ensure it stays stable and effective.

In short, mandelic acid is a gentle yet powerful AHA that exfoliates, brightens, and helps clarify skin while keeping irritation low. Its antibacterial action makes it especially beneficial for those with acne-prone, sensitive, or uneven skin, offering smoother, clearer, and more even-toned results over time.

Read more about some other popular AHA's here:

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.

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.

You'll likely see this ingredient in "clean" formulations because it's considered a natural alternative to PEGs.

Patch testing at concentration 0.1-1% showed no reactions and this ingredient is considered to be well-tolerated across skin types.

Due to its myristic acid base, this ingredient may not be fungal acne safe.

Because it has a C12 (lauric acid) fatty acid chain, this ingredient can potentially feed the Malassezia yeast that causes fungal acne. The Malassezia yeast prefers esters with C11-C24 fatty acids If you're prone to flare-ups, you might want to patch-test or skip this one.

This ingredient is an ester of lauric acid and Polyglycerin-10.

Research shows it can encourage your skin cells to turn over and renew by stimulating keratinocyte and fibroblast proliferation.

It also has mild keratolytic properties to help loosen and shed dead skin cells without being harsh.

Studies also suggest allantoin can help calm inflammation by dialing down some of the chemical signals your skin sends out when it is irritated.

This ingredient is typically used in the 0.1-0.5% range, and the FDA recognizes it as a skin protectant in OTC products up to 2%.

Overall, allantoin is a wonderful addition to most routines; it is stable across a wide pH range (~4-8), works well with other ingredients, and is considered non-sensitizing/non-irritating.

Fun fact: Allantoin is naturally occurring in comfrey root, beets, chamomile, and wheat sprouts. Our bodies even produce it as a byproduct of uric acid metabolism.

You'll usually find this in concentrations between 0.2-5%.

Studies show Madecassic Acid helps soothe the skin due to its ability to block inflammation pathways.

As an antioxidant, asiatic acid helps protect our skin against damaging environmental factors.

Studies show tannic acid may have help reduce photoaging. However, further studies are needed.

According to a manufacturer, it also offer some moisturizing effects.

Like salicylic acid, this ingredient is a chemical exfoliant that can help break down the oil in your pores and reduce inflammation.

Though studies for LHA do show it to be less effective than salicylic acid. To be fair, salicylic acid is the reigning monarch of acne treatments.

However, a study from 2009 found LHA to be comparable to BPO, making it a good alternative for people with sensitive skin. Another study of 14 patients found a significant decrease in comedones after using LHA.

Another pro of LHA? It is less irritating than salicylic acid due to its large molecule size.

Large molecules cannot penetrate skin as well, so they are gentler on the skin. LHA is much less penetrative than salicylic acid.

An in-vitro study (not done on a living organism) found only 6% of LHA penetrated past the statum corneum compared to 58% of salicylic acid. An in-vivo (done on a living organism) analysis revealed ~17% of LHA was still present in the top layer of skin after 4 days, versus ~9% of salicylic acid.

Interestingly, a study from 2008 found LHA comparable to another famous acid, glycolic acid.

This study found about 10% of LHA is as effective as 20-50% of glycolic acid in treating hyperpigmentation and fine-lines.

Hydroxy acids have been found to stimulate skin protein, lipids, and thermal thickening. This may have anti-aging benefits.

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

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.

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.

It is synthetic and reported use concentrations are very low (up to 0.086% in face powders).