Korean skincare ingredients glossary: centella, snail mucin, niacinamide and more

By the Real Korea 101 editorial team · Published November 13, 2026 · Sources checked November 13, 2026

Short answer: The ingredients you see most on Korean skincare are a mix of plant extracts (centella asiatica), animal-derived materials (snail mucin), vitamins (niacinamide, a form of vitamin B3) and substances that already exist in human skin (ceramides and hyaluronic acid). Each has a clear scientific definition, but the evidence behind them varies a lot, from decades of skin barrier research on ceramides to mostly small studies on snail mucin. Korea also sets fixed amounts for a few ingredients, such as niacinamide at 2 to 5 percent, when a product claims a regulated "functional" effect.

The ingredients at a glance

Centella asiatica

What it is: A 2013 review in Postepy Dermatologii i Alergologii describes Centella asiatica, known as gotu kola, as a medicinal plant used in folk medicine for hundreds of years as well as in scientifically oriented medicine. Its main active compounds are pentacyclic triterpenes, chiefly asiaticoside, madecassoside, asiatic acid and madecassic acid. You may see these compound names on Korean ingredient lists too.

What research says: The same review reports that centella has been effective in improving the treatment of small wounds, hypertrophic wounds and burns, and that its mechanism involves promoting fibroblast growth and collagen synthesis. It adds that research results indicate it can be used for photoaged skin, cellulite and stretch marks. Keep in mind that much of this work concerns wound care and medical use, not a cosmetic toner used once a day. A cosmetic in Korea, by law, is defined as having light effects on the body.

Snail mucin

What it is: Snail mucin is the secretion snails produce. A 2024 review in the Journal of Cosmetic Dermatology notes that it contains a wide range of components and has become increasingly popular in cosmetic formulas.

What research says: The review lists medical research on snail mucin as an antimicrobial agent, drug delivery vehicle and wound healing agent, and cosmetic uses including anti-aging, hydrating, anti-acne, scarring and hyperpigmentation products. It is direct about the limits: most studies were preclinical or small clinical studies, and the authors call for larger clinical trials to support these claims. They also list allergy investigation and ethical collection as open issues.

Practical note: If you have known allergies to snails or shellfish, ask the brand before using it. We did not find official guidance on that specific question, so treat this as caution, not a rule.

Niacinamide

What it is: A 2024 review in Drug Delivery and Translational Research defines niacinamide as an active form of vitamin B3. It says niacinamide is recognized for skin brightening, anti-ageing properties and protection of the skin barrier, and that its wide use, from cleansers to serums, is due to its safety profile and proven efficacy.

What research says: The review collects clinical evidence for cosmetic uses and for some skin conditions, including dermatitis, acne and actinic keratosis. It also explains why the formula matters: how much niacinamide actually gets into the skin depends on how the product is designed.

Korean rules: MFDS's Regulation on the Review of Functional Cosmetics lists niacinamide at 2 to 5 percent among the ingredients a company can use for a "helps whitening of the skin" functional claim without submitting new efficacy data, in forms such as lotions, liquids, creams, solids and sheet masks. A product with niacinamide outside that framework can still be sold as a regular cosmetic, but it should not make the regulated whitening claim unless it went through the MFDS process.

Ceramides

What it is: A 2003 review in the American Journal of Clinical Dermatology describes ceramides as the major lipid in the layered sheets between cells of the stratum corneum, the outermost layer of skin. Together with cholesterol and free fatty acids, in roughly equal amounts, they form the structure that gives skin its water barrier. Ceramides are a varied group of lipids built from a sphingoid base linked to a fatty acid.

What research says: That review notes that most skin disorders with a weakened barrier show lower total ceramide content, and that formulas with skin-identical lipids could improve disturbed skin, while incomplete lipid mixtures can disrupt the layers. A 2021 review in the Journal of Dermatology selected 12 reports and found that ceramide-containing preparations can improve dry skin and barrier function in people with atopic dermatitis, while calling for larger double-blind studies. A 2024 review in the International Journal of Cosmetic Science adds a formulation point: ceramides need specific processing to dissolve properly, and undissolved ceramides worked against barrier repair in lab models.

Hyaluronic acid

What it is: A 2025 review in Biomolecules defines hyaluronic acid (also called hyaluronan) as a glycosaminoglycan, a type of long sugar chain, with key roles in skin, including hydration and the skin's mechanical properties. A 2021 study in Dermatology and Therapy describes it as a biologic humectant, meaning it retains water in the skin.

What research says: The 2025 review reports that hyaluronic acid below 100 kDa penetrates skin, with smaller forms able to reach deeper layers, and that the safety of hyaluronic acid formulas is supported by several clinical trials. In the 2021 study, 40 women aged 30 to 65 used one hyaluronic acid serum twice a day with sunscreen for six weeks; skin hydration measured by an instrument was 55 percent higher than at the start at week 6. That is one product in one small study, and its abstract does not describe a comparison group, so it does not tell you how other serums perform.

Ingredients with fixed amounts in Korean rules

Korea's Cosmetics Act treats some claims, including skin whitening, wrinkle improvement and UV protection, as "functional cosmetic" claims that need an MFDS evaluation or report. The MFDS regulation then lists specific ingredients and amounts that companies can use for these claims without submitting new efficacy data. A few examples you are likely to see:

Products making these claims must show the words "functional cosmetic" (기능성화장품) or the MFDS mark on the package, under Article 10 of the Cosmetics Act. For sunscreen labels in detail, see our guide to SPF and PA on Korean sunscreen.

How to use this glossary on a label

1. Read the full ingredient list, not just the front. Look for the ingredient names in this article, including compound names such as madecassoside.
2. Check for the functional cosmetic mark if the product promises whitening, wrinkle improvement or UV protection.
3. Match the claim to the evidence. "Hydrating" fits what is known about hyaluronic acid and ceramides. Medical-sounding promises from any cosmetic are a reason for caution, because Korean law bans cosmetic ads that could be mistaken for medicine.
4. Patch test new products. The American Academy of Dermatology suggests applying a new product to a small area, such as the inner arm, twice a day for 7 to 10 days.

Curious about the salmon DNA ingredient? See what PDRN skincare is. Building a routine from scratch? Start with our beginner routine guide.

This article explains public information and is not medical advice. For skin conditions, talk to a dermatologist.