Skincare Ingredient Dictionary

3-O-Ethyl Ascorbic Acid

3-O-ethyl ascorbic acid, usually written as ethyl ascorbic acid or EAC, is one of the most popular next-generation vitamin C derivatives, and for good reason. It attaches a small ethyl group to the vitamin C molecule, which greatly improves stability while keeping the derivative close to the structure of pure ascorbic acid. That means it converts efficiently into active vitamin C in the skin and is one of the better-performing derivatives for brightening, yet it is more stable and often less irritating than L-ascorbic acid. It shows up across all price points, from budget serums to prestige brightening treatments.

Acetyl Glucosamine

Acetyl glucosamine, often shortened to NAG, is an amino sugar with a quiet but useful set of skin benefits. It is a building block your body uses to make hyaluronic acid, so it supports the skin's own moisture-binding molecules, and it is used as a gentle brightening ingredient, especially in combination with niacinamide, in products aimed at the appearance of dark spots and uneven tone. Because it is well tolerated and non-comedogenic, NAG is a good option for people who want to work on hydration and hyperpigmentation without the sting of an acid or the strength of a retinoid.

Acrylates Copolymer

Acrylates copolymer is a synthetic film-forming polymer that quietly does a lot of the heavy lifting in mattifying primers, long-wear makeup, sunscreens and oil-control products. Its main talent is forming a thin, flexible, water-resistant film as a product dries, which can hold pigments in place, keep sunscreen filters evenly spread and give skin a smooth, shine-free finish. Some grades also act as tiny sponges that soak up excess surface oil, which is why the ingredient turns up so often in products aimed at oily and combination skin.

Charcoal Powder

Activated charcoal is a fine, highly porous black powder that has become a signature ingredient in oil-control masks and cleansers. Its appeal comes from its enormous internal surface area, which lets it adsorb oil and grime from the skin's surface during a wash-off treatment. It is genuinely useful for mopping up excess sebum and giving oily skin a temporarily clean, matte feel, but its powers are frequently overstated. Charcoal cannot draw impurities from deep within pores, and it does not detox the skin — understanding what it actually does keeps expectations realistic.

Adapalene

Adapalene is a topical retinoid that has become one of the most widely used acne ingredients since a 0.1% version became available over the counter in several markets, with higher strengths remaining prescription-only. Like other retinoids it is a vitamin A derivative, but it was engineered to be more selective and more stable than older molecules, which gives it a somewhat gentler tolerance profile than tretinoin while still working on the underlying causes of acne. It targets both the clogged pores that start breakouts and the inflammation that turns them red and painful. As a retinoid, however, it carries the same important caution as retinol: it must not be used during pregnancy.

Adenosine

Adenosine is a small, biologically important molecule that your cells use constantly for energy and signalling, and in skincare it has become a quietly popular anti-aging and soothing ingredient. It is a naturally occurring nucleoside — a building block related to DNA and to the energy molecule ATP — and applied topically at very low concentrations it appears to send signals that support skin renewal and calm. It is best known as a gentle, well-tolerated smoothing active in serums, eye creams and firming products, and it carries approval as an anti-wrinkle active in some regulatory systems, which is unusual for a cosmetic ingredient.

Allantoin

Allantoin is a quiet workhorse ingredient that rarely gets top billing but appears in an enormous number of moisturisers, soothing creams and after-treatment products. Originally isolated from the comfrey plant and now made synthetically for purity and consistency, it is prized for a single, well-defined job: calming and conditioning the skin. It has no strong action of its own — it does not exfoliate aggressively, brighten or fight bacteria — but it makes almost every other ingredient more comfortable to use. For people managing acne, that supporting role is exactly the point, because the treatments that clear breakouts are frequently the ones that leave skin raw, and allantoin softens that blow.

Aloe Barbadensis Leaf Juice

Aloe vera is one of the oldest and most universally recognised skin soothers, a clear gel harvested from the fleshy leaves of Aloe barbadensis. Its reputation rests on comfort: it calms hot, irritated, sunburned or over-exfoliated skin, delivers light water-based hydration and feels instantly cooling. Because it is watery, non-greasy and non-comedogenic, it suits every skin type, including oily and acne-prone complexions that struggle with heavier moisturisers. It is not a powerful treatment active, but as a gentle, well-tolerated support ingredient for calming and hydrating, few things match its track record.

Alpha-Arbutin

Alpha-arbutin is a stable, well-tolerated brightening ingredient prized for fading dark spots, melasma and the lingering brown marks left behind by acne. It is a naturally derived molecule in which a glucose unit is attached to hydroquinone, and that bond is the whole point: it releases its pigment-blocking action slowly and gently rather than all at once, which makes it far kinder to the skin than raw hydroquinone while still targeting the same enzyme. Effective concentrations sit around 1–2%, and because it does not exfoliate or lower the skin's pH, most people tolerate it without any sting.

Thioctic Acid

Alpha-lipoic acid, often abbreviated ALA and listed by its INCI name thioctic acid, is a distinctive antioxidant because it is soluble in both water and oil. That dual solubility, sometimes called being 'amphipathic', means it can work throughout the skin's watery and fatty compartments, which sets it apart from antioxidants that are limited to one or the other. Naturally made in the body and involved in energy metabolism, ALA is used in skincare for its antioxidant power and its reputation for improving the look of texture and radiance. It can be a potent addition to an anti-aging routine, though it needs sensible formulation and use because it can be irritating.

Aminomethyl Propanol

Aminomethyl propanol, commonly abbreviated AMP, is a pH adjuster used in very small amounts to bring a product to the right acidity or alkalinity. Like triethanolamine, one of its main jobs is to neutralize acidic gelling agents such as carbomer so they thicken into clear, stable gels. Formulators often favor AMP as a modern, efficient neutralizer that works at low use levels and helps create smooth, clear textures. Because only a tiny, balanced amount is needed, it sits far down the ingredient list even though it is essential to how the finished gel behaves.

Ammonium Acryloyldimethyltaurate/VP Copolymer

Behind its intimidating name, ammonium acryloyldimethyltaurate/VP copolymer, often shortened to AVC, is simply one of the most useful modern texture polymers in skincare. Formulators love it because it thickens water instantly, does not need a separate neutralizing step, and can even hold small amounts of oil in place, letting it act as a light emulsifier as well as a gelling agent. The payoff you feel is a smooth, elegant gel-cream texture that spreads easily and absorbs without stickiness, which is why AVC appears in so many hydrating serums, gel moisturizers and lightweight lotions.

Prunus Armeniaca Kernel Oil

Apricot kernel oil is a soft, pale-yellow oil pressed from the kernels inside apricot stones. It is a gentle, widely available and affordable facial and body oil, popular for dry, sensitive and mature skin and often used in massage and baby-care products because of its mild character. It has a light-to-medium feel, a faint nutty scent and sinks in at a moderate pace, which makes it an easy everyday oil rather than a specialty active. It sits in the middle of the comedogenic scale, so it suits most skin types but calls for a little care on very oily skin.

Argania Spinosa Kernel Oil

Argan oil, extracted from the kernels of the Moroccan argan tree, is a nourishing facial and body oil famous for its high vitamin E content and rich, conditioning feel. It has a balanced fatty-acid profile and a notable dose of tocopherols and polyphenols, which give it both emollient and antioxidant value. It shines on dry, mature and normal skin that benefits from extra softening and cushioning, leaving skin supple without a heavy residue. Despite being a facial oil, it carries a low comedogenic rating, so it is generally friendlier to a wider range of skin than its rich reputation might suggest.

Arginine

Arginine is an amino acid that plays several supporting roles in skincare, from hydration to acting as a gentle, natural pH adjuster in a formula. Amino acids are the building blocks of the proteins that structure skin, and several of them, arginine included, are part of the skin's own natural moisturising factor. On the skin, arginine helps bind water, offers some antioxidant defence against the free radicals generated by stress and sunlight, and has been studied for a role in the skin's repair processes. It is gentle, non-comedogenic and useful across skin types, appearing in everything from soothing serums to anti-aging creams.

Acetyl Hexapeptide-8

Argireline, the trade name for acetyl hexapeptide-8, is the peptide often marketed as Botox in a bottle for its supposed ability to relax expression lines. That comparison sets expectations far too high, but argireline is a real and gentle cosmetic peptide with a plausible mechanism and a place in anti-aging serums aimed at fine lines around the forehead and eyes. It has a comedogenic rating of 0 and low irritation risk, so it is comfortable to use. As with every topical peptide, honest framing matters: a serum cannot replicate an injectable, and results are subtle at best.

Arnica Montana Flower Extract

Arnica extract is a mountain flower with a strong reputation in traditional medicine for calming the look of bumps, bruises and stressed skin. Drawn from Arnica montana, it appears in soothing gels, after-sun products, post-procedure creams and formulas marketed for sensitive or reactive skin. Its folk history is long, and many people reach for arnica products after minor knocks. In skincare it is used for its soothing, conditioning character, but arnica comes with an important caveat: as a daisy-family plant it is a recognised contact allergen, so it demands more caution than a plain, hypoallergenic soother, especially on broken or very sensitive skin.

Ascorbyl Glucoside

Ascorbyl glucoside is a vitamin C derivative built for stability. Where pure vitamin C fights a constant battle against oxygen and light, ascorbyl glucoside links the vitamin C molecule to a glucose sugar, which effectively caps the reactive site and keeps the ingredient intact in the bottle for far longer. On the skin, an enzyme called alpha-glucosidase snips the sugar off and releases active vitamin C gradually. This slow, steady delivery makes ascorbyl glucoside a gentle, low-drama choice for people who want the brightening and antioxidant benefits of vitamin C but find L-ascorbic acid too irritating or too unstable to bother with.

Ascorbyl Palmitate

Ascorbyl palmitate is one of the original oil-soluble vitamin C esters, and you will find it in everything from moisturisers to food products, where it doubles as an antioxidant preservative. It combines vitamin C with palmitic acid, a fatty acid, which makes it soluble in oils and lipids rather than water. In skincare it is used both to give a mild vitamin C benefit and to help protect the oils in a formula from going rancid. It is gentle and non-acidic, though it is generally considered a weaker skin-brightening vitamin C than the phosphate salts or ethyl ascorbic acid, and its stability in finished products is only moderate.

Ascorbyl Tetraisopalmitate

Ascorbyl tetraisopalmitate, sometimes labelled VC-IP or ATIP, is a stable, oil-soluble vitamin C derivative closely related to tetrahexyldecyl ascorbate. Like that ingredient, it wraps the vitamin C molecule in fatty chains to make it lipid-loving, stable and non-irritating, so it can be used in luxurious oil and cream textures without the sting of L-ascorbic acid. It is a common choice in Japanese and Korean anti-aging serums, where it is valued for penetrating the skin's lipid layers and for its role in brightening and supporting collagen. Because it is fat-soluble and comfortable, it suits dry, mature and even sensitive skin.

Astaxanthin

Astaxanthin is a deep-red carotenoid antioxidant, the pigment that gives salmon and some algae their color, and one of the more potent antioxidants used in skincare. It is typically sourced from the microalga Haematococcus pluvialis and used at very low concentrations because a little goes a long way and it stains intensely. In skincare it is valued for defending the skin against oxidative and environmental stress and supporting a healthier-looking complexion. It has a low comedogenic rating and low irritation risk, making it a gentle, antioxidant-focused addition to anti-aging and protective routines.

Butyl Methoxydibenzoylmethane

Avobenzone is the most widely used chemical UVA filter in the world, and for many years it was the only broad UVA absorber approved for over-the-counter sunscreens in the United States. Its job is to soak up the long-wave ultraviolet light (UVA) that penetrates deep into the skin, drives photoaging and contributes to pigmentation and some skin cancers. Almost every American broad-spectrum sunscreen relies on it, and it appears throughout European formulas as well. Its great weakness is instability: on its own, avobenzone breaks down within minutes of sun exposure, so formulators must pair it with stabilizing partners to keep it working through the day.

Persea Gratissima Oil

Avocado oil is one of the richest and most nourishing plant oils used on skin, pressed from the flesh of the avocado rather than a seed. It is deeply emollient, loaded with fatty acids, vitamin E and other fat-soluble nutrients, and it sinks in to leave dry, depleted skin feeling soft and cushioned. That richness is exactly why it is a wonderful ingredient for dry, mature and normal skin, and just as clearly why it is not a good match for acne-prone skin. With a comedogenic rating of around 3, avocado oil sits at the higher end for pore-clogging potential, so its generous nourishment comes with a caveat for anyone who breaks out easily.

Azelaic Acid

Azelaic acid is a versatile, well-tolerated active that treats several concerns at once: acne, the redness of rosacea, and post-inflammatory pigmentation. A dicarboxylic acid found naturally in grains like wheat and barley, it works through gentler mechanisms than exfoliating AHAs, which makes it unusually kind to sensitive skin while still being effective. It is available over the counter at around 10% and by prescription at higher strengths, and it holds a valuable place in skincare because it is one of the few genuinely effective actives widely regarded as safe to use during pregnancy — a period when retinoids and many other treatments are off the table.

Potassium Azeloyl Diglycinate

Azeloyl glycine, whose full INCI name is potassium azeloyl diglycinate and which is often abbreviated PAD, is a modern, water-soluble derivative of azelaic acid. Traditional azelaic acid is a well-regarded ingredient for acne, redness and uneven tone, but it can be tricky to formulate and a little gritty or irritating. PAD was created to solve those problems: it is easy to dissolve, non-irritating and even hydrating, while retaining a gentler version of azelaic acid's benefits for oily, blemish-prone and uneven skin. It is a comfortable, multitasking ingredient that suits people wanting azelaic-style results in a milder, more elegant form.

Bakuchiol

Bakuchiol is a plant-derived ingredient that has gained attention as a gentler alternative to retinol. Extracted from the seeds and leaves of the babchi plant (Psoralea corylifolia), it is not chemically a retinoid at all, yet early research suggests it can switch on some of the same skin pathways that retinol does — supporting a smoother, firmer, more even-looking complexion — while being far better tolerated. That combination makes it popular with people whose skin cannot cope with the dryness and irritation of true retinoids, including those with sensitive or reactive skin. It is generally regarded as a preferred alternative during pregnancy, though the data are still limited.

Adansonia Digitata Seed Oil

Baobab oil is a golden, nutty oil pressed from the seeds of the iconic African baobab tree, the huge, bottle-shaped tree of the savannah. It is a well-balanced, easy-going facial oil that sits comfortably between the light linoleic oils and the rich oleic ones, which makes it flexible across a range of skin types. It absorbs at a moderate pace, has a mild scent and stores reasonably well, so it has become a popular base oil in nourishing serums and balms for dry and mature skin without being especially heavy.

Cera Alba

Beeswax, listed on labels as Cera Alba, is the natural wax that honeybees produce to build their honeycomb, and it has been used in skin salves for thousands of years. In modern formulations it plays a dual role: it is a protective emollient that softens and shields the skin, and it is a structural ingredient that gives balms, lip products and thick creams their firm, stable texture. It forms a breathable protective film on the surface that helps guard against moisture loss and environmental exposure without being as heavily occlusive as petrolatum. Generally well tolerated, it is a mainstay of natural and minimalist skincare.

Behenic Acid

Behenic acid is one of the longer fatty acids used in cosmetics, and it does its work quietly inside rich creams and conditioners. Because its carbon chain is long, it is a waxy solid that adds body, structure and a velvety softness to formulas. You will find it in nourishing moisturisers, cleansing balms and especially in hair conditioners, where it helps deposit a smooth, detangling layer. It is not a marketed active, but it is a dependable texture and stability ingredient, and it is only mildly comedogenic, so it fits comfortably into products aimed at dry and mature skin without being a common breakout trigger.

Bentonite

Bentonite is a highly absorbent clay formed from weathered volcanic ash, and one of the most powerful oil-drawing ingredients in mask form. Where kaolin is gentle, bentonite is strong: it swells when mixed with water and has a marked ability to bind and pull excess oil and debris from the skin's surface, which is why it is a favourite for very oily and congested skin. That strength is also its main caution, because overzealous use can leave skin uncomfortably tight and dry. Used sensibly as an occasional mask, it can noticeably reduce shine and give a deep-cleaned feel.