Beauty ingredient research

Beauty ingredients explained in plain English

Browse the review database to understand what an ingredient is, what it does in a beauty formula, when it is useful, and when it deserves caution across skincare, haircare, bodycare, makeup, and more.

20769

Reviewed ingredients

524

Low-concern standouts

2884

Need usage caution

Showing 60 of 20,769
AllUV absorberUV filterabrasiveabsorbentacne treatmentactiveactive ingredientadhesivealkalizing agentamino acidanti-aginganti-androgenanti-cavityanti-cavity agentanti-inflammatoryanti-irritantanticariesanticavity agentantidandruffantifungalantimicrobialantioxidantantiperspirantantiplaqueastringentbarrier repairbarrier supportbarrier-repairbarrier-supportbinderbinding agentbiotechbiotechnologybond-builderbotanicalbotanical extractbotanical oilbotanical waterbrighteningbrightening agentbufferbuffering agentcell-communicating ingredientceramidechelating agentchemicalchemical intermediateclaycleansercleansingcleansing agentcolorantconditionerconditioningconditioning agentcooling agentcosmeticcosmetic additivecosmetic colorantcosmetic ingredientcosmetic pigmentcosmetic powdercosmetic-texturizercosmetic-waxcosmeticscrosslinking agentdelivery agentdelivery systemdenaturantdeodorantdeodorant agentdepigmenting agentdepilatorydepilatory agentdesensitizing agentdyedye intermediatedye precursordye-intermediateemollientemulsifierenzymeessential oilexfoliantexperimentaleyelashfermentfilm formerfilm-formerfilm-formingfilm-forming agentfirming agentfixativeflavoring agentformulationfragrancefragrance ingredientfunctional ingredientgashair carehair colorhair coloranthair conditionerhair dyehair removalhair-carehair-colorhaircarehumectantindustrialinsecticideintermediatelashlash carelash enhancerlash-and-browlip carelipidmakeupmarine extractmasking agentmicrobiomemicrobiome modulatormineralmoisturizernail carenail-careocclusiveoilopacifieropacifying agentoptical agentoral careotheroxidative dyeoxidative dye precursoroxidizing agentpH adjusterpain reliefpenetration enhancerpeptidepersonal careph adjusterpharmaceuticalpheromonepigmentplant oilplasticizerpolymerpolymer precursorprebioticprescription-drugpreservativepreservative boosterprobioticprocessing agentprocessing aidpropellantproteinpurifyingreducing agentretinoidscalp caresebum regulatorsebum-regulatorself-tannerself-tanningsensory additivesensory agentsensory modifiersiliconeskin barrierskin barrier supportskin conditionerskin conditioningskin conditioning agentskin lighteningskin protectantskin-conditioningskin-conditioning agentskin-identicalskin-identical ingredientskin-lighteningskin-lightening agentskincaresolventsoothingsoothing agentstabilizerstimulantsunscreensurfactantsyntheticsynthetic colorantsynthetic dyesynthetic resinsynthetic-coloranttexture enhancertexturizerthickenertoneruv-absorberuv-filtervasoactivevasodilatorviscosity controlviscosity controllingviscosity controlling agentvitaminwax

Emollient

Isomerized Jojoba Oil

ISOMERIZED JOJOBA OIL

4.3

A lightweight, non-greasy emollient that closely resembles skin's natural oils, making it ideal for all skin types including oily and acne-prone.

Irritation

low

Source

natural

beautyskincareemollient
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Skin conditioning agent

Isomerized Linalool Acid

LINALOOL ACID ISOMERIZED

3.5

A modified form of linalool that may offer antioxidant benefits with lower irritation potential than its parent compound.

Irritation

low

Source

semi-synthetic

beautyskincareantioxidant
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Antioxidant

Isomerized Linoleyl Gallate

ISOMERIZED LINOLEYL GALLATE

4.0

A gentle antioxidant that helps protect skin from environmental stress while supporting a smoother, more even complexion.

Irritation

low

Source

semi-synthetic

beautyskincareantioxidant
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Emollient

Isomerized Safflower Acid

ISOMERIZED SAFFLOWER ACID

4.0

A gentle, skin-friendly fatty acid that helps reinforce the skin barrier and improve moisture retention without clogging pores.

Irritation

low

Source

semi-synthetic

beautyskincareemollient
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Emollient

Isomerized Safflower Glycerides

ISOMERIZED SAFFLOWER GLYCERIDES

4.0

A lightweight, non-greasy emollient derived from safflower oil that helps soften and smooth skin without clogging pores.

Irritation

low

Source

semi-synthetic

beautyskincareemollient
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Fragrance Ingredient

Isomethyl Ionone

Isomethyl-β-Ionone

3.5

Isomethyl ionone is a common synthetic fragrance that gives a pleasant floral scent, but it may cause allergic reactions in sensitive individuals.

Irritation

low

Source

synthetic

beautyskincarefragrance
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Surfactant

Isomyreth-3

ISOMYRETH-3

3.5

Isomyreth-3 is a synthetic emulsifier that helps mix oil and water, but it may be mildly irritating for sensitive skin.

Irritation

moderate

Source

synthetic

beautyskincaresurfactant
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Surfactant

Isomyreth-9

ISOMYRETH-9

3.5

Isomyreth-9 is a synthetic emulsifier that helps cleansers foam and rinse cleanly, but it may be slightly drying for sensitive skin.

Irritation

moderate

Source

synthetic

beautyskincaresurfactant
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Anti-inflammatory

Isoniacinamide

ISONIACINAMIDE

3.5

Isoniacinamide is a less-studied relative of niacinamide that may offer similar anti-inflammatory benefits, but research is still early.

Irritation

low

Source

synthetic

beautyskincareactive
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Fragrance ingredient

Isononanal

Isononanal

3.5

Isononanal is a synthetic fragrance ingredient that adds a citrusy scent, but it may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyskincarefragrance
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Skin Conditioning

Isononyl Acetate

Isononyl Acetate

3.8

A gentle synthetic ester that helps dissolve other ingredients and leaves skin feeling smooth without heavy residue.

Irritation

low

Source

synthetic

beautyskincaresolvent
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Solvent

Isononyl Alcohol

ISONONYL ALCOHOL

3.5

A safe, synthetic fatty alcohol that helps products spread smoothly and feel less greasy, but offers no active skin benefits.

Irritation

low

Source

synthetic

beautyskincaresolvent
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Antioxidant

Isononyl Ferulate

Isononyl Ferulate

4.0

A gentle, oil-soluble antioxidant that helps protect skin from environmental stress without the stability issues of pure ferulic acid.

Irritation

low

Source

semi-synthetic

beautyskincareantioxidant
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Emollient

Isononyl Isononanoate

Isononyl Isononanoate

4.0

A lightweight, non-greasy emollient that spreads easily and leaves a silky feel, ideal for those who dislike heavy oils.

Irritation

low

Source

synthetic

beautyskincareemollient
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Emollient

Isononyl Propionate

Isononyl Propionate

4.0

A lightweight synthetic emollient that softens skin without greasiness, widely used for its silky feel and compatibility with other ingredients.

Irritation

low

Source

synthetic

beautyskincareemollient
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Fragrance Ingredient

Isooctanal Diethyl Acetal

Isooctanal Diethyl Acetal

3.5

A synthetic fragrance ingredient that adds a fresh scent but offers no skincare benefits; safe at low levels but may cause sensitivity in some people.

Irritation

low

Source

synthetic

beautyskincarefragrance
Read ingredient review

Solvent

Isooctane

Isooctane

3.5

Isooctane is a lightweight solvent that helps dissolve oils and makeup, but it can be drying or irritating for sensitive skin.

Irritation

moderate

Source

synthetic

beautyskincaresolvent
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Solvent

Isooctanol

ISOOCTANOL

3.5

Isooctanol is a synthetic alcohol that helps dissolve other ingredients and gives a silky feel, but it can be drying or irritating for sensitive skin.

Irritation

moderate

Source

synthetic

beautyskincaresolvent
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Anti-aging agent

Isooctanoyl Tetrapeptide-25

Isooctanoyl Tetrapeptide-25

4.0

A lab-made peptide that may help soften expression wrinkles and improve skin firmness with minimal irritation risk.

Irritation

low

Source

synthetic

beautyskincarepeptide
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Emollient

Isooctyl Caprylate/Caprate

Isooctyl Caprylate/Caprate

4.0

A lightweight, non-greasy emollient that helps soften skin and improve product texture without clogging pores.

Irritation

low

Source

synthetic

beautyskincareemollient
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Emollient

Isooctyl Lactoyl Tallate

ISOOCTYL LACTOYL TALLATE

3.5

A gentle synthetic emollient that helps soften and smooth the skin with a low risk of irritation or clogged pores.

Irritation

low

Source

synthetic

beautyskincareemollient
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Emollient

Isooctyl Polyhydroxystearate

ISOOCTYL POLYHYDROXYSTEARATE

4.0

A lightweight, non-greasy emollient that helps products spread smoothly and leaves skin feeling soft without clogging pores.

Irritation

low

Source

synthetic

beautyskincareemollient
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Emollient

Isooctyl Tallate

ISOOCTYL TALLATE

3.8

A lightweight, non-greasy emollient that helps soften skin and improve product texture, generally well-tolerated.

Irritation

low

Source

semi-synthetic

beautyskincareemollient
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Reducing Agent

Isooctyl Thioglycolate

Isooctyl Thioglycolate

2.5

A strong chemical used to break hair bonds for perms or straightening; effective but can be irritating and requires careful handling.

Irritation

high

Source

synthetic

beautyhaircarereducing agent
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Fragrance Ingredient

Isopentanal

ISOPENTANAL

3.5

Isopentanal is a synthetic fragrance ingredient that adds a sweet, fruity note but may cause skin irritation in sensitive individuals at higher concentrations.

Irritation

moderate

Source

synthetic

beautyskincarefragrance
Read ingredient review

Solvent

Isopentane

ISOPENTANE

3.8

Isopentane is a lightweight solvent that helps products feel less greasy, but it can be drying for very sensitive or dry skin.

Irritation

low

Source

synthetic

beautyskincaresolvent
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Fragrance Ingredient

Isopentenol

3-ISOPENTENOL

3.0

Isopentenol is a synthetic fragrance ingredient with limited safety data; it may cause irritation in sensitive individuals and is best avoided if you prefer fragrance-free skincare.

Irritation

moderate

Source

synthetic

beautyskincarefragrance
Read ingredient review

Emollient

Isopentenyl Isopentenoate

3-ISOPENTENYL 2-ISOPENTENOATE

3.5

A gentle synthetic emollient that helps soften and smooth skin with a low risk of irritation or clogged pores.

Irritation

low

Source

synthetic

beautyskincareemollient
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Fragrance Ingredient

Isopentenyl Isovalerate

3-ISOPENTENYL ISOVALERATE

3.5

A synthetic fragrance ester with limited research; generally considered safe at low concentrations but may cause sensitivity in some individuals.

Irritation

low

Source

synthetic

beautyskincarefragrance
Read ingredient review

Soothing agent

Isopentenyl Phenethyl Ether

2-ISOPENTENYL PHENETHYL ETHER

3.5

A synthetic compound that may help calm skin and support its natural defenses, but research is still early.

Irritation

low

Source

synthetic

beautyskincaresoothing agent
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Fragrance Ingredient

Isopentenyl Salicylate

2-Isopentenyl Salicylate

3.5

A synthetic fragrance ester with mild skin-conditioning properties, generally safe but may cause sensitivity in those allergic to fragrance ingredients.

Irritation

low

Source

synthetic

beautyskincarefragrance
Read ingredient review

Skin conditioning agent

Isopentyl Caprylamide

Isopentyl Caprylamide

3.5

A gentle synthetic ingredient that helps improve the feel and conditioning of skincare and hair products, with a low risk of irritation.

Irritation

low

Source

synthetic

beautyskincareconditioning agent
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Fragrance Ingredient

Isopentyl Cyclohexyl Acetate

ISOPENTYL CYCLOHEXYL ACETATE

3.5

A synthetic fragrance ingredient that adds a pleasant scent but offers no skincare benefits; generally safe at low concentrations.

Irritation

low

Source

synthetic

beautyskincarefragrance
Read ingredient review

Fragrance Ingredient

Isopentylcyclohexanone

ISOPENTYLCYCLOHEXANONE

3.5

A synthetic scent ingredient that adds a pleasant floral-woody note but may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyskincarefragrance
Read ingredient review

Humectant

Isopentyldiol

Isopentyldiol

4.0

A gentle, multi-tasking humectant that hydrates skin and helps other ingredients work better without causing irritation.

Irritation

low

Source

synthetic

beautyskincarehumectant
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Film Former

Isophorone Diamine Copolymer

ISOPHORONE DIAMINE/ISOPHTHALIC ACID/TROMETHAMINE COPOLYMER

3.5

A synthetic film-former that helps products stay put, but offers no active skincare benefit.

Irritation

low

Source

synthetic

beautyskincarehaircare
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Film Former

Isophoronediamine Copolymer

ISOPHORONEDIAMINE/ISOPHTHALIC ACID/PENTAERYTHRITOL COPOLYMER

3.5

A synthetic film former that helps makeup and sunscreen stay put longer, but offers no active skincare benefits.

Irritation

low

Source

synthetic

beautyskincarehaircare
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pH Adjuster

Isophthalic Acid

Isophthalic Acid

2.5

Isophthalic acid is a synthetic pH adjuster rarely used in leave-on skincare; it's more common in nail and hair color products where precise pH control is needed.

Irritation

moderate

Source

synthetic

beautyskincarepH adjusterbuffering agent
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Film Former

Isoprene/Pentadiene Copolymer

ISOPRENE/PENTADIENE COPOLYMER

3.5

A synthetic polymer that helps makeup and sunscreen stay put and resist water, but offers no skincare benefit.

Irritation

low

Source

synthetic

beautyskincarefilm-former
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pH Adjuster

Isopropanolamine

ISOPROPANOLAMINE

3.5

Isopropanolamine is a synthetic pH adjuster that helps keep formulas stable, but it can be a mild irritant for sensitive skin.

Irritation

moderate

Source

synthetic

beautyskincarepH adjuster
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Emulsifier

Isopropanolamine Lanolate

Isopropanolamine Lanolate

3.5

A gentle lanolin-based emulsifier that helps blend oil and water, but may be mildly comedogenic for acne-prone skin.

Irritation

low

Source

semi-synthetic

beautyskincareemulsifier
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Fragrance

Isopropenyl-Methylhexenol

ISOPROPENYL-METHYLHEXENOL

3.5

A synthetic fragrance ingredient that adds a pleasant scent but may cause irritation for sensitive skin.

Irritation

moderate

Source

synthetic

beautyskincarefragrance
Read ingredient review

Fragrance

Isopropoxyethyl Benzene

ISOPROPOXYETHYL-BENZENE

2.5

Isopropoxyethyl Benzene is a synthetic fragrance ingredient with limited safety data; it may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyskincarefragrance
Read ingredient review

Fragrance Ingredient

Isopropyl 3-Methylthiobutyrate

ISOPROPYL 3-METHYLTHIOBUTYRATE

3.5

A synthetic fragrance ingredient that adds a fruity note but offers no skincare benefit; safe at low levels but may cause sensitivity in some individuals.

Irritation

low

Source

synthetic

beautyskincarefragrance
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Fragrance Ingredient

Isopropyl 3-Methylthiocrotonate

ISOPROPYL 3-METHYLTHIOCROTONATE

3.5

A synthetic fragrance compound that adds unique sulfurous notes to products; generally safe at low concentrations but offers no skincare benefit.

Irritation

low

Source

synthetic

beautyskincarefragrance
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Solvent

Isopropyl Acetate

ISOPROPYL ACETATE

3.5

Isopropyl acetate is a fast-evaporating solvent that helps products dry quickly, but it can be drying or irritating for sensitive skin.

Irritation

moderate

Source

synthetic

beautyskincaresolvent
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Solvent

Isopropyl Alcohol

ISOPROPYL ALCOHOL

3.5

Effective for quick-drying and sanitizing, but can be drying and irritating for sensitive or dry skin types.

Irritation

moderate

Source

synthetic

beautyskincaresolvent
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Emollient

Isopropyl Arachidate

ISOPROPYL ARACHIDATE

4.0

A reliable synthetic emollient that softens skin but may clog pores for those prone to breakouts.

Irritation

low

Source

synthetic

beautyskincareemollient
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Emollient

Isopropyl Avocadate

ISOPROPYL AVOCADATE

4.0

A gentle, avocado-derived emollient that hydrates and softens skin without feeling greasy.

Irritation

low

Source

semi-synthetic

beautyskincareemollient
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Emollient

Isopropyl Babassuate

Isopropyl Babassuate

4.3

A lightweight, plant-based emollient that gives skin a silky feel without clogging pores.

Irritation

low

Source

semi-synthetic

beautyskincareemollient
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Emollient

Isopropyl Behenate

Isopropyl Behenate

4.0

A lightweight synthetic emollient that softens skin without heavy residue, generally well-tolerated and non-comedogenic.

Irritation

low

Source

synthetic

beautyskincareemollient
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Emollient

Isopropyl Benzoate

ISOPROPYL BENZOATE

4.0

A lightweight synthetic emollient that helps products glide on smoothly without a greasy feel.

Irritation

low

Source

synthetic

beautyskincareemollient
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Emollient

Isopropyl Butyrate

Isopropyl Butyrate

4.0

A lightweight synthetic ester that softens skin without a greasy feel, but may not suit those with very sensitive or acne-prone skin.

Irritation

low

Source

synthetic

beautyskincareemollient
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Fragrance

Isopropyl Cinnamate

ISOPROPYL CINNAMATE

3.5

Isopropyl Cinnamate is a synthetic fragrance ingredient that adds a sweet, balsamic scent to products, but it may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyskincarefragrance
Read ingredient review