Ingredient guide

What each active does, and what it can be layered with.

The actives behind Korean skincare, in plain language: what they are for, how to use them, which pairings irritate, and the products in our catalog that contain them.

Actives

The ingredient guide

18 actives, grouped by what they do.

Acne TreatmentAzelaic AcidA gentle acid that calms redness, reduces acne and fades post-blemish marks by slowing pigment production. It is one of the few actives considered suitable for rosacea-prone skin and during pregnancy.In 8 products in our catalog
Acne TreatmentBenzoyl PeroxideAn antibacterial that kills the acne bacterium C. acnes by releasing oxygen into the pore. Bacteria do not become resistant to it, which keeps it a mainstay of acne treatment. It dries the skin and bleaches fabric.Not in our catalog yet
AntioxidantVitamin C (L-Ascorbic Acid)L-ascorbic acid is the form of vitamin C with the strongest evidence for brightening, fading dark spots and neutralizing the free radicals that UV exposure creates. It is also the least stable form: light and air oxidize it, and it turns yellow-orange as it loses potency.In 44 products in our catalog
AntioxidantVitamin C DerivativeAscorbyl glucoside, sodium ascorbyl phosphate and THD ascorbate are stabilized forms of vitamin C. The skin converts them to ascorbic acid slowly, trading some strength for a longer shelf life and much less irritation.In 33 products in our catalog
Barrier SupportCeramidesLipids that make up around half of the skin's outer barrier, the mortar between the cells. Topping them up cuts water loss and helps irritated or over-exfoliated skin recover.In 11 products in our catalog
Barrier SupportNiacinamideVitamin B3. It helps skin make its own ceramides, regulates oil and reduces the pigment transfer behind dark marks. It is one of the best-tolerated actives there is, which is why it appears in more K-beauty products than any other.In 173 products in our catalog
Barrier SupportSnail Secretion FiltrateSnail secretion filtrate is a mix of glycoproteins, hyaluronic acid and small amounts of glycolic acid. It hydrates and helps skin recover, in a texture that layers without stickiness.In 9 products in our catalog
Chemical ExfoliantAHA (Glycolic / Lactic Acid)Water-soluble acids that loosen the bonds between dead cells on the skin's surface. Glycolic acid is the smallest and strongest, lactic acid also hydrates, and mandelic acid is the gentlest. Regular use smooths rough texture and brightens dull skin.In 22 products in our catalog
Chemical ExfoliantBHA (Salicylic Acid)Salicylic acid is oil-soluble, so it works inside the pore instead of only on the surface. It clears blackheads and congestion and calms inflammation a little, which makes it the acid of choice for oily and acne-prone skin.In 37 products in our catalog
Chemical ExfoliantPHA (Gluconolactone / Lactobionic Acid)Gluconolactone and lactobionic acid exfoliate like AHAs, but their larger molecules penetrate more slowly, so they sting far less. They also draw in water, which is why PHAs are the usual suggestion for sensitive skin that cannot tolerate glycolic acid.In 31 products in our catalog
FirmingPeptidesShort chains of amino acids that act as messengers in the skin. Signal peptides such as Matrixyl are studied for firmness and fine lines, and copper peptides for repair. The effect is subtler than a retinoid's, but they are very gentle.In 19 products in our catalog
HumectantHyaluronic AcidA humectant that holds many times its weight in water and plumps the outer layers of the skin. Small, hydrolyzed forms sink in further while larger ones sit on the surface and smooth it. It hydrates, but it does not seal moisture in.In 54 products in our catalog
ProtectionSunscreen (SPF)UV filters absorb or reflect ultraviolet light before it damages skin. Daily SPF prevents burning, dark spots and most visible aging, and it is what makes acids and retinoids safe to use. Korean sunscreens are known for light textures and modern filters.In 64 products in our catalog
RetinoidAdapaleneA third-generation retinoid made for acne. It unclogs pores and calms inflammation with less irritation than tretinoin, and at 0.1 percent it is sold without a prescription in many countries.Not in our catalog yet
RetinoidRetinolA form of vitamin A that speeds up cell turnover and stimulates collagen. Over months it softens fine lines, fades marks and keeps pores clear. The skin has to convert retinol into retinoic acid before it works, which makes it slower and gentler than prescription tretinoin.In 25 products in our catalog
RetinoidTretinoinPrescription retinoic acid, the form of vitamin A the skin actually uses. It is the most studied topical treatment for both acne and sun damage, and the strongest retinoid most people will ever use.Not in our catalog yet
SoothingCentella AsiaticaCentella asiatica, or cica, is a medicinal plant whose compounds madecassoside and asiaticoside soothe irritation and support skin repair. It is the backbone of Korean calming skincare.In 80 products in our catalog
SoothingPanthenolPro-vitamin B5. Skin converts it to pantothenic acid, which draws in moisture and supports barrier repair. Its calming effect is why it turns up in so many soothing creams.In 64 products in our catalog

Layering

Can I use these together?

Every pairing our Routine Check knows about, with the reason behind each answer.