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 83
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

Dye intermediate

1,3-Bis-(2,4-Diaminophenoxy)Propane

1,3-BIS-(2,4-DIAMINOPHENOXY)PROPANE

3.0

A synthetic dye ingredient used in permanent hair color; it can cause skin irritation in sensitive individuals and is not used in leave-on skincare.

Irritation

moderate

Source

synthetic

beautyhair colordye intermediate
Read ingredient review

Hair colorant

2-Amino-6-Chloro-4-Nitrophenol

2-AMINO-6-CHLORO-4-NITROPHENOL

2.5

A synthetic hair dye ingredient that can effectively deposit color but may cause skin irritation or allergic reactions in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colordye
Read ingredient review

Hair colorant

2-Chloro-6-Ethylamino-4-Nitrophenol

2-CHLORO-6-ETHYLAMINO-4-NITROPHENOL

3.0

A synthetic hair dye ingredient that provides yellow tones in permanent color, but may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colordye
Read ingredient review

Hair colorant

2-Chloro-p-Phenylenediamine Sulfate

2-CHLORO-P-PHENYLENEDIAMINE SULFATE

2.5

A common synthetic dye in permanent hair color that can cause allergic reactions in sensitive individuals; generally considered safe at regulated levels but requires patch testing.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Hair colorant

2-Methoxy-p-Phenylenediamine Sulfate

2-METHOXY-P-PHENYLENEDIAMINE SULFATE

2.5

A common synthetic dye in permanent hair color that can cause allergic reactions in sensitive individuals; patch testing is strongly recommended.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Dye precursor

2-Methoxymethyl-P-Phenylenediamine

2-METHOXYMETHYL-P-PHENYLENEDIAMINE

3.5

A common hair dye intermediate that provides long-lasting color but may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colordye precursor
Read ingredient review

Hair Dye Intermediate

2-Methoxymethyl-P-Phenylenediamine Sulfate

2-METHOXYMETHYL-P-PHENYLENEDIAMINE SULFATE

3.0

A common hair dye intermediate that helps create natural-looking permanent color, but requires careful formulation to minimize skin irritation.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic
Read ingredient review

Hair colorant

2-Nitro-5-Glyceryl Methylaniline

2-NITRO-5-GLYCERYL METHYLANILINE

3.5

A synthetic blue dye used in hair color; generally safe for most people but may cause irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Hair colorant intermediate

2,4-Diaminophenoxyethanol HCl

2,4-DIAMINOPHENOXYETHANOL HCL

3.5

A synthetic hair dye intermediate that helps create certain shades but may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colordye precursor
Read ingredient review

Hair colorant

2,6-Diaminopyridine Sulfate

2,6-DIAMINOPYRIDINE SULFATE

3.0

A synthetic dye ingredient that helps create cool, ashy hair colors but may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair coloroxidative dye
Read ingredient review

Hair Dye Intermediate

2,6-Dimethyl-p-Phenylenediamine

2,6-DIMETHYL-P-PHENYLENEDIAMINE

2.5

A synthetic hair dye intermediate that can effectively color hair but may cause skin irritation or allergic reactions in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colorchemical
Read ingredient review

Hair color intermediate

3-Amino-2,4-Dichlorophenol HCl

3-AMINO-2,4-DICHLOROPHENOL HCL

2.5

A synthetic hair dye intermediate that helps create specific shades but may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colorintermediate
Read ingredient review

Hair colorant intermediate

3-Amino-2,6-Dimethylphenol

3-Amino-2,6-Dimethylphenol

2.8

A synthetic hair dye intermediate that helps create certain shades but may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic
Read ingredient review

Hair Dye

4-Amino-2-Hydroxytoluene

4-AMINO-2-HYDROXYTOLUENE

2.5

A synthetic dye ingredient used in permanent hair color; it can cause skin irritation in sensitive individuals and requires careful formulation to minimize risks.

Irritation

moderate

Source

synthetic

beautyhair colordye intermediate
Read ingredient review

Hair colorant

4-Amino-2-Hydroxytoluene Sulfate

4-AMINO-2-HYDROXYTOLUENE SULFATE

3.0

A synthetic dye used in permanent hair color; effective for color but may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Hair colorant

4-Amino-3-Nitrophenol

4-AMINO-3-NITROPHENOL

3.0

A synthetic dye used in hair color; generally safe in regulated amounts but can cause irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colordye
Read ingredient review

Hair colorant

4-Amino-m-Cresol

4-AMINO-M-CRESOL

3.5

A synthetic hair dye ingredient that helps create long-lasting color but may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colordye
Read ingredient review

Hair colorant

4-Nitro-o-Phenylenediamine HCl

4-NITRO-O-PHENYLENEDIAMINE HCL

2.5

A synthetic hair dye ingredient that can cause allergic reactions in sensitive individuals; its safety is regulated but requires caution.

Irritation

moderate

Source

synthetic

beautyhair colordye
Read ingredient review

Hair colorant

4-Nitro-o-Phenylenediamine Sulfate

4-NITRO-O-PHENYLENEDIAMINE SULFATE

2.5

A synthetic hair dye ingredient that can provide color but may cause skin irritation or allergic reactions in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colordye
Read ingredient review

Hair colorant

5-Amino-4-Chloro-o-Cresol

5-AMINO-4-CHLORO-O-CRESOL

3.0

A synthetic hair dye ingredient that helps create certain shades but may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colorcolorant
Read ingredient review

Colorant

5-Amino-6-Chloro-o-Cresol

5-AMINO-6-CHLORO-O-CRESOL

3.0

A synthetic hair dye colorant that is generally safe when used as directed, but may cause irritation for sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colorcolorant
Read ingredient review

Hair colorant

Basic Brown 17

Basic Brown 17

3.5

Basic Brown 17 is a synthetic dye that adds brown tones to hair color, but it may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Colorant

Basic Orange 69

Basic Orange 69

2.5

Basic Orange 69 is a synthetic hair dye that delivers vibrant orange tones but may cause irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Colorant

Dihydroxyethylaminotoluene

2,6-Dihydroxyethylaminotoluene

3.0

A synthetic dye ingredient used in permanent hair color; it can be effective but may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Oxidative dye precursor

Dihydroxyindoline HBr

DIHYDROXYINDOLINE HBR

3.5

A synthetic hair dye intermediate that helps create rich, lasting color but may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair coloroxidative dye precursor
Read ingredient review

Hair colorant

Dimethoxypyridinediamine HCl

2,6-DIMETHOXY-3,5-PYRIDINEDIAMINE HCL

2.5

A synthetic dye ingredient used in hair color; can cause skin irritation in sensitive individuals and is not used in leave-on skincare.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Colorant

Ethylamino Cresol Sulfate

3-ETHYLAMINO-P-CRESOL SULFATE

2.5

A synthetic hair dye ingredient that helps create specific shades but may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic colorant
Read ingredient review

Colorant

HC Blue No. 12

HC Blue No. 12

3.0

HC Blue No. 12 is a synthetic blue dye for hair color that is generally considered safe in small amounts but may cause irritation for sensitive scalps.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Colorant

HC Blue No. 13

HC Blue No. 13

3.5

HC Blue No. 13 is a synthetic blue dye for hair color, generally considered safe in rinse-off products but may cause irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Hair colorant

HC Blue No. 14

HC Blue No. 14

3.5

HC Blue No. 14 is a synthetic hair dye that adds blue tones but may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Colorant

HC Blue No. 16

HC Blue No. 16

3.5

A synthetic blue dye for hair color that is generally safe for most people but may cause allergic reactions in sensitive individuals.

Irritation

low

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Colorant

HC Blue No. 17

HC Blue No. 17

3.5

HC Blue No. 17 is a synthetic hair dye that delivers blue tones but may cause irritation for sensitive scalps.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Hair colorant

HC Orange No. 1

HC Orange No. 1

2.8

HC Orange No. 1 is a synthetic dye for orange hair color, but it may cause skin irritation in sensitive individuals and has limited safety data for long-term use.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Hair colorant

HC Orange No. 5

HC Orange No. 5

3.5

HC Orange No. 5 is a synthetic dye that adds orange tones to hair color, but it may cause irritation in sensitive individuals and has limited safety data for long-term use.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Hair colorant

HC Orange No. 6

HC Orange No. 6

3.5

HC Orange No. 6 is a synthetic dye that adds orange tones to hair color, but it may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Hair colorant

HC Red 18

2,6-DIAMINO-3-((PYRIDIN-3-YL)AZO)PYRIDINE

3.5

HC Red 18 is a synthetic dye that adds red shades to hair color, but it may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Colorant

HC Red No. 1

HC RED NO. 1

3.0

HC Red No. 1 is a synthetic hair dye that adds red tones but may cause irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Hair Colorant

HC Red No. 10

HC Red No. 10

3.5

HC Red No. 10 is a synthetic dye used in hair color products; it is generally considered safe for external use but may cause irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Hair colorant

HC Red No. 11

HC Red No. 11

3.5

HC Red No. 11 is a synthetic hair dye that adds red tones but may cause irritation in sensitive individuals or with frequent use.

Irritation

moderate

Source

synthetic

beautyhair colordye
Read ingredient review

Colorant

HC Red No. 13

HC RED NO. 13

3.5

A synthetic red hair dye that can deliver vibrant color but may cause irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Hair colorant

HC Red No. 14

HC RED NO. 14

3.5

HC Red No. 14 is a synthetic dye used in hair color products; it is generally considered safe for use on hair but may cause irritation for sensitive scalps.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Hair colorant

HC Violet No. 2

HC Violet No. 2

3.5

HC Violet No. 2 is a synthetic hair dye that adds violet tones but may cause irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Colorant

HC Yellow No. 17

HC Yellow No. 17

3.5

HC Yellow No. 17 is a synthetic yellow dye for hair color that is generally considered safe in rinse-off products but may cause irritation for sensitive scalps.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Hair colorant

HC Yellow No. 2

HC YELLOW NO. 2

3.5

HC Yellow No. 2 is a synthetic dye that adds yellow tones to hair color, but it may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Hair colorant

HC Yellow No. 4

HC YELLOW NO. 4

3.5

HC Yellow No. 4 is a synthetic hair dye that adds yellow shades to hair color products, but it may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Colorant

HC Yellow No. 7

HC Yellow No. 7

3.5

HC Yellow No. 7 is a synthetic hair dye that can provide vibrant yellow shades, but it may cause irritation in sensitive individuals and is not intended for skin or eyelash use.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review

Hair colorant

Hexyl Diamino Pyrazole Sulfate

1-HEXYL 4,5-DIAMINO PYRAZOLE SULFATE

3.5

A synthetic dye ingredient that helps create vivid hair colors, but may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colordye precursor
Read ingredient review

Hair colorant

Hydroxyethyl Diamino Pyrazole Sulfate

1-HYDROXYETHYL 4,5-DIAMINO PYRAZOLE SULFATE

3.5

A synthetic dye ingredient that helps create red and violet hair colors, but may cause skin irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyhair colordye precursor
Read ingredient review

Colorant

Hydroxyethyl-2-Nitro-P-Toluidine

HYDROXYETHYL-2-NITRO-P-TOLUIDINE

3.5

A synthetic yellow dye used in hair color; generally considered safe in small amounts but may cause irritation for sensitive scalps.

Irritation

moderate

Source

synthetic

beautyhair colorsynthetic dye
Read ingredient review