The library

Ingredient library

Every ingredient SkinAtlas knows about — all 2161 of them. What each one does, what it works well with, and what to watch for.

130 ingredients matching "acid" — page 1 of 6

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Active
2-O-Ethyl Ascorbic Acid
3-O-ETHYL ASCORBIC ACID

An ether derivative of L-ascorbic acid in which the 3-OH position is protected by an ethyl group, making it stable in water-based formulas. Converts to Vitamin C inside skin cells. Used widely in Japanese brightening products (Shiseido, Elixir) as a quasi-drug-adjacent brightening active.

antioxidantskin-brighteningcollagen-synthesis
Stable Vitamin C derivative that brightens skin and evens tonePromotes collagen synthesisLess irritating than L-ascorbic acid at equivalent concentration
May cause mild tingling on sensitive skin at high concentrations
+ Niacinamide+ Tocopherol+ Tranexamic Acid
Antioxidant
3-O-Ethyl Ascorbic Acid

A stable vitamin C derivative that converts to ascorbic acid in the skin to brighten and provide antioxidant protection.

brighteningantioxidant
Stable, water-soluble vitamin C derivativeBrightens and evens skin toneHelps fade hyperpigmentation
+ Niacinamide+ Tocopherol+ Hyaluronic Acid
Other
Acetic Acid

The pure synthetic acid (INCI: Acetic Acid) used at trace levels as a pH adjuster in cosmetic formulas, distinct from Vinegar (Acetum).

ph-adjustersolvent
Lowers and adjusts formula pHImproves preservative efficacy at low pH
Concentrated form is corrosive; cosmetic use levels are highly diluted
Other
Adipic Acid
ADIPIC ACID

A straight-chain dicarboxylic acid used in cosmetics as a pH buffer and chelating agent. Extremely well-tolerated; appears in mist sprays and lightweight lotions where precise pH control is needed.

buffering agentchelating agentpH adjuster
Stabilises formula pHMild chelating action that supports preservative efficacy
+ Arginine+ Phenoxyethanol+ Disodium EDTA
Humectant
Alanine

A naturally occurring amino acid used as a humectant that helps maintain skin hydration and supports the NMF.

humectantamino-acid
Attracts and binds moistureSupports the skin's natural moisturizing factors (NMF)
Other
Alanine Glutamate

An INCI-listed combination ingredient pairing the amino acids alanine and glutamic acid (glutamate), used in Korean prestige formulas as a skin-conditioning agent that contributes to the amino acid profile of the skin's natural moisturizing factor.

Skin conditioningAmino acid complex
Delivers two amino acids (alanine and glutamate) to skin simultaneouslyConditions skinSupports natural moisturizing factor
Emollient
Aleuritic Acid

9,10,16-Trihydroxyhexadecanoic acid, a naturally occurring hydroxy fatty acid found in shellac resin secreted by Kerria lacca (lac insect). Used in cosmetics as an emollient and skin-conditioning agent with mild antimicrobial properties. The three hydroxyl groups give it some humectant character alongside its primary emollient role. Appears in ceramide-rich formulas (such as Holika Holika Good Cera) for its lipid-compatible moisturizing properties.

skin-conditioningemollientantimicrobial
Trihydroxy fatty acid with lipid-compatible structure that integrates smoothly into the skin surfaceNaturally occurring in shellac (Kerria lacca resin), giving it a natural/bio-origin positioningMild antimicrobial activity contributes secondary preservation support in multi-ingredient formulas
Shellac-derived — may not be suitable for strict vegans; animal origin (lac insect) should be disclosed for vegan certifications
+ Ceramide NP+ Cholesterol+ Shea Butter
Other
Algin
ALGIN

The sodium salt of alginic acid extracted from brown seaweed (Phaeophyta spp.). Used as a natural hydrocolloid thickener, film-former, and gel-stabiliser in skincare.

thickeningfilm-formingemulsifying
Natural seaweed-derived thickenerForms a moisture-retaining film on skinSoothing gel texture
+ Xanthan Gum+ Hydroxyapatite+ Glycerin
Barrier support
Arachidic Acid

A C20 saturated fatty acid naturally occurring in peanut oil, fish oils, and skin lipids, used as an emollient and barrier-supportive ingredient in skincare formulations.

emollientbarrier-supportskin-conditioning
Replenishes skin lipids as a long-chain fatty acidContributes to barrier integrity alongside ceramides and cholesterolProvides emollient softening of the skin
May be comedogenic for some skin types at high concentrations
Humectant
Arginine

A naturally occurring amino acid that acts as a humectant and supports the skin's own moisture-retention system.

humectantamino-acid
Attracts and retains moistureSupports skin's natural moisturizing factors
Active
Ascorbic Acid

Pure vitamin C; a potent antioxidant and brightener.

antioxidantvitamin-c
BrightensBoosts collagenAntioxidant protection
Unstable formulaCan sting
+ Tocopherol+ Ferulic Acid
× Retinol× Retinal
Antioxidant
Ascorbyl Dipalmitate
ASCORBYL DIPALMITATE

The dipalmitoyl ester of ascorbic acid (vitamin C). An oil-soluble vitamin C derivative with improved stability vs. pure ascorbic acid. Penetrates lipid-rich skin layers. Used in Lululun's Hydra EX mask.

antioxidantskin-brightening
Oil-soluble vitamin C — good skin penetrationAntioxidant protectionSkin brightening
Fat-soluble form; less studied than ascorbic acid for brightening efficacy
+ Tocopherol+ Ferulic Acid
Soothing
Asiatic Acid

A centella-derived triterpene active in the 'madecassic/asiatic' family, valued for soothing and barrier-supporting effects.

soothingantioxidant
Calms rednessSupports skin repair
+ Centella Asiatica Extract+ Madecassic Acid+ Asiaticoside
Other
Asparagine

A non-essential amino acid (L-asparagine) used as a skin-conditioning agent in cosmetics, typically as part of amino acid complex formulas that mimic the skin's natural moisturizing factor.

Skin conditioningAmino acid
Provides amino acid substrate for skin protein synthesisConditions skin
Humectant
Aspartic Acid

A naturally occurring amino acid that functions as a humectant and is a component of the skin's natural moisturizing factor.

humectantamino-acid
Attracts and retains moistureSupports the skin's natural moisturizing factor (NMF)
Active
Azelaic Acid

A multitasker for redness, acne and pigmentation.

soothing
Calms redness and rosaceaFades pigmentationHelps acne
Temporary tingling on application
+ Niacinamide
Emollient
Behenic Acid
BEHENIC ACID

A 22-carbon saturated long-chain fatty acid. Forms the free acid component paired with bases to create soap-like emulsifiers in luxury creams and serums. Found naturally in small amounts in rapeseed and peanut oil.

emollientthickeneremulsifier
Provides rich, creamy emollient textureHelps stabilise emulsions
+ Behenyl Alcohol+ Potassium Hydroxide
Preservative
Benzoic Acid

An aromatic acid used as a cosmetic preservative and pH adjuster, effective in acidic formulas; the free-acid form of sodium benzoate.

preservativeph-adjuster
Broad-spectrum antimicrobial preservationEffective in acidic formulas
Can cause non-immunologic contact urticaria (flushing/stinging) in some individuals, especially in products for infantsCIR and SCCS deem safe up to 2.5% rinse-off and 0.5% leave-on; manufacturers advised caution in infant products
Emollient
Branched Fatty Acid (C10-40) Cholesterol Esters
BRANCHED FATTY ACID (C10-40) CHOLESTEROL ESTERS

Ester mixture of cholesterol with branched C10-40 fatty acids. Mimics the composition of sebum, making it highly compatible with skin lipids. Used in luxury Japanese skincare (Kanebo, POLA) for barrier-restoring emolliency.

emollientbarrier-supportskin-conditioning
Structurally similar to sebum lipidsSupports skin barrier functionNon-greasy emollient
+ Cholesterol+ Ceramide NP+ Squalane
Antioxidant
Caffeic Acid

A naturally occurring hydroxycinnamic acid found in coffee, wine, and many plants; potent antioxidant used in prestige creams for its UV-protective, anti-inflammatory, and brightening polyphenol activity.

antioxidantanti-inflammatorybrightening
Hydroxycinnamic acid with potent antioxidant and UV-protective propertiesAnti-inflammatory activity helps reduce rednessMay inhibit melanin synthesis for a mild brightening effect
+ Tocopherol+ Ascorbic Acid
Preservative
Capryl Hydroxamic Acid

A hydroxamic acid derivative of caprylic acid used as a preservative and chelating agent. Considered a mild, natural-derived preservative alternative to parabens.

preservativechelating
Broad-spectrum antimicrobial preservative derived from coconut oil (caprylic acid)Often combined with 1,2-Hexanediol for a paraben-free preservation system
May cause irritation in sensitive individuals at higher concentrations
+ 1,2-Hexanediol
Preservative
Caprylhydroxamic Acid

A hydroxamic acid preservative and chelator derived from caprylic acid that inhibits microbial growth by depriving bacteria and fungi of essential metal ions; popular in 'clean' and 'preservative-free' labelled formulas.

preservativechelator
Broad-spectrum antimicrobial preservation via metal-ion chelationEffective at low concentrations (≤0.3%)Compatible with a wide pH range
Typically combined with glycols for full-spectrum preservation; less effective alone against all microorganism classes
Emollient
Caprylic/Capric Triglyceride

A lightweight emollient ester derived from coconut oil.

Softens skinImproves spreadability
Emollient
Capryloyl Glycerin/Sebacic Acid Copolymer

A semisynthetic polyester copolymer of glycerin, sebacic acid (castor-derived), and caprylic acid (coconut-derived) used as a biodegradable silicone alternative that films and conditions skin.

emollientfilm-formerskin-conditioning
Forms an occlusive, moisture-retaining film on skinLightweight silicone-alternative emollient feelBiodegradable and plant-derived
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