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 20,303
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

Cell-communicating ingredient

Hydroxypinacolone Retinoate

Hydroxypinacolone Retinoate

4.3

A gentle yet effective retinoid that works like retinoic acid without the typical redness and peeling.

Irritation

low

Source

semi-synthetic

beautyskincareanti-aging
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Plasticizer

Hydroxypivalyl Hydroxypivalate

3-Hydroxy-2,2-dimethylpropyl hydroxypivalate

3.5

A synthetic ester that helps nail polishes and hair products form flexible, durable films without making them brittle.

Irritation

low

Source

synthetic

beautyskincarenail care
Read ingredient review

Humectant

Hydroxyproline

Hydroxyproline

4.0

Hydroxyproline is a collagen-building amino acid that may help firm and hydrate skin with minimal irritation risk.

Irritation

low

Source

natural

beautyskincarehumectant
Read ingredient review

Skin conditioning agent

Hydroxyproline Palmitamide

Hydroxyproline Palmitamide

4.0

A gentle peptide-like ingredient that may help improve skin firmness and hydration with low irritation risk.

Irritation

low

Source

semi-synthetic

beautyskincareconditioning agent
Read ingredient review

Film Former

Hydroxypropyl Acrylate

2-HYDROXYPROPYL ACRYLATE

3.0

An effective film-former for nail products, but not a common or recommended ingredient in everyday facial skincare due to potential irritation and limited benefit.

Irritation

moderate

Source

synthetic

beautyskincarefilm-former
Read ingredient review

Antistatic Agent

Hydroxypropyl Biscetearyldimonium Chloride

Hydroxypropyl Biscetearyldimonium Chloride

3.5

A gentle synthetic conditioning agent that helps detangle and soften hair without heavy buildup, but may not suit those avoiding quaternary ammonium compounds.

Irritation

low

Source

synthetic

beautyskincarehaircare
Read ingredient review

Hair Conditioning Agent

Hydroxypropyl Bislauramide MEA

Hydroxypropyl Bislauramide MEA

3.8

A gentle synthetic ingredient that helps hair feel soft and smooth without heavy buildup, but it's not a star performer on its own.

Irritation

low

Source

synthetic

beautyskincarehaircare
Read ingredient review

Skin Conditioning Agent

Hydroxypropyl Bispalmitamide MEA

Hydroxypropyl Bispalmitamide MEA

4.0

A gentle synthetic ingredient that helps condition skin and stabilize formulas, with a low risk of irritation.

Irritation

low

Source

synthetic

beautyskincareemulsifier
Read ingredient review

Antistatic Agent

Hydroxypropyl Bistrimonium Diiodide

Hydroxypropyl Bistrimonium Diiodide

3.5

A synthetic conditioning agent that helps reduce static and improve manageability, but its iodine content raises mild safety questions for sensitive skin.

Irritation

moderate

Source

synthetic

beautyskincareconditioning agent
Read ingredient review

Film Former

Hydroxypropyl Methacrylate

Hydroxypropyl Methacrylate

3.5

A synthetic film-former that helps nail polish and some cosmetics resist wear and water, but may cause irritation in sensitive individuals.

Irritation

moderate

Source

synthetic

beautyskincarefilm-former
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Thickener

Hydroxypropyl Oxidized Starch

Hydroxypropyl Oxidized Starch

4.0

A gentle, plant-derived thickener that improves texture and stability without clogging pores or irritating skin.

Irritation

low

Source

semi-synthetic

beautyskincarethickener
Read ingredient review

Humectant

Hydroxypropyl Streptococcus Ferment

HYDROXYPROPYL STREPTOCOCCUS ZOOEPIDEMICUS FERMENT FILTRATE

4.0

A gentle, biotech-derived humectant that boosts skin hydration and supports a healthy moisture barrier without irritation.

Irritation

low

Source

biotech

beautyskincarehumectant
Read ingredient review

Humectant

Hydroxypropyl Tetrahydropyrantriol

Hydroxypropyl Tetrahydropyrantriol

4.0

A gentle, synthetic humectant that draws moisture into the skin without the stickiness of glycerin, making it a good option for lightweight hydration.

Irritation

low

Source

synthetic

beautyskincarehumectant
Read ingredient review

Viscosity Controlling

Hydroxypropylcellulose

Hydroxypropylcellulose

4.0

A safe, plant-derived thickener that gives products a smooth, non-greasy feel and helps stabilize formulas.

Irritation

low

Source

semi-synthetic

beautyskincaretexturizer
Read ingredient review

Skin conditioner

Hydroxypropyldimethicone

Hydroxypropyldimethicone

4.0

A gentle silicone that improves product feel and spreadability with a very low risk of irritation or clogged pores.

Irritation

low

Source

synthetic

beautyskincarehaircare
Read ingredient review

Solvent

Hydroxypropylene Carbonate

Hydroxypropylene Carbonate

3.5

A synthetic solvent that helps other ingredients blend and spread, but has limited direct skin benefit and is best reserved for nail and hair formulas.

Irritation

low

Source

synthetic

beautyskincaresolvent
Read ingredient review

Humectant

Hydroxypropylgluconamide

Hydroxypropylgluconamide

4.0

A gentle, sugar-derived humectant that helps hydrate skin without stickiness, suitable for sensitive and dry skin types.

Irritation

low

Source

semi-synthetic

beautyskincarehumectant
Read ingredient review

Antioxidant

Hydroxypropyltrimonium Ascorbate

Hydroxypropyltrimonium Ascorbate

4.3

A gentle, stable vitamin C derivative that brightens skin and fights free radicals without the sting of pure ascorbic acid.

Irritation

low

Source

semi-synthetic

beautyskincareantioxidant
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Film Former

Hydroxypropyltrimonium Gelatin

Hydroxypropyltrimonium Gelatin

3.8

A gentle, protein-derived conditioning ingredient that helps reduce static and smooth hair without heavy buildup.

Irritation

low

Source

semi-synthetic

beautyskincarehaircare
Read ingredient review

Hair Conditioning Agent

Hydroxypropyltrimonium Honey

Hydroxypropyltrimonium Honey

4.0

A gentle, positively charged honey derivative that helps hair and skin retain moisture and reduces static without the stickiness of raw honey.

Irritation

low

Source

semi-synthetic

beautyskincarehaircare
Read ingredient review

Humectant

Hydroxypropyltrimonium Hyaluronate

Hydroxypropyltrimonium Hyaluronate

4.3

A gentle, high-performance hyaluronic acid derivative that sticks to skin better than standard HA for deeper, longer-lasting hydration.

Irritation

low

Source

semi-synthetic

beautyskincarehumectant
Read ingredient review

Hair conditioning agent

Hydroxypropyltrimonium Hydrolyzed Casein

HYDROXYPROPYLTRIMONIUM HYDROLYZED CASEIN

4.0

A gentle, protein-based conditioning ingredient that helps strengthen hair and improve manageability with low irritation risk.

Irritation

low

Source

semi-synthetic

beautyskincarehaircareconditioning agent
Read ingredient review

Hair Conditioning Agent

Hydroxypropyltrimonium Hydrolyzed Whey

Hydroxypropyltrimonium Hydrolyzed Whey

4.0

A gentle, protein-derived conditioning ingredient that adds softness and manageability to hair without heavy buildup.

Irritation

low

Source

semi-synthetic

beautyskincarehaircareconditioning agent
Read ingredient review

Hair Conditioner

Hydroxypropyltrimonium Inulin

Hydroxypropyltrimonium Inulin

4.3

A gentle, plant-based conditioning ingredient that makes hair softer and less frizzy without heavy buildup.

Irritation

low

Source

semi-synthetic

beautyskincarehaircareconditioning agent
Read ingredient review

Hair conditioning agent

Hydroxypropyltrimonium Lemon Protein

HYDROXYPROPYLTRIMONIUM LEMON PROTEIN

3.8

A gentle, plant-derived conditioning ingredient that helps detangle hair and soften skin without heavy buildup.

Irritation

low

Source

semi-synthetic

beautyskincarehaircareconditioning agent
Read ingredient review