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 1,094
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

Humectant

Hydroxyethyl Urea

Hydroxyethyl Urea

4.3

A gentle, effective humectant that hydrates without the stickiness of glycerin or the potential irritation of regular urea.

Irritation

low

Source

synthetic

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Humectant

Hydroxyisoleucine

Hydroxyisoleucine

4.0

A gentle amino acid that helps hydrate and calm the skin, making it a good choice for sensitive or dry skin types.

Irritation

low

Source

natural

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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

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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

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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

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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

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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

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Humectant

Ice Plant Juice

MESEMBRYANTHEMUM CRYSTALLINUM JUICE

4.0

A gentle, mineral-rich plant juice that helps hydrate and calm the skin, but scientific evidence is still emerging.

Irritation

low

Source

natural

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Humectant

Ice Plant Water

Carpobrotus Edulis Water

3.8

A gentle, hydrating plant water that may help soothe and protect the skin, but research is limited.

Irritation

low

Source

natural

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Humectant

Inositol

INOSITOL

4.0

Inositol is a gentle humectant that helps hydrate and soothe the skin, making it a good option for sensitive or dry skin types.

Irritation

low

Source

natural

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Humectant

Inositol Hexa-PCA

Inositol Hexa-PCA

4.0

A gentle, multi-tasking humectant that helps hydrate and soothe the skin, making it a good choice for sensitive or dry skin types.

Irritation

low

Source

semi-synthetic

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Humectant

Inulin

Inulin

4.2

Inulin is a gentle, plant-derived prebiotic that hydrates and supports a balanced skin microbiome, making it a smart choice for sensitive or microbiome-conscious routines.

Irritation

low

Source

natural

beautyskincarehumectantprebiotic
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Humectant

Irish Moss Extract

Chondrus Elatus Extract

4.0

A gentle, hydrating seaweed extract that helps skin retain moisture and feel soothed, ideal for dry or sensitive skin types.

Irritation

low

Source

natural

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Humectant

Ishige Foliacea Extract

Ishige Foliacea Extract

4.0

A gentle brown algae extract that helps hydrate and protect skin with antioxidant benefits, though research is still emerging.

Irritation

low

Source

natural

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Humectant

Isoleucine

Isoleucine

4.0

Isoleucine is a gentle amino acid that helps maintain skin hydration and supports the skin's natural repair processes.

Irritation

low

Source

natural

beautyskincarehumectantamino acid
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Humectant

Isomalt

Isomalt

4.0

Isomalt is a gentle, sugar-derived humectant that helps skin retain moisture without stickiness.

Irritation

low

Source

semi-synthetic

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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

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Humectant

Isopropyl PCA

Isopropyl PCA

4.0

Isopropyl PCA is a gentle, synthetic humectant that helps hydrate skin without feeling heavy, making it a good option for normal to dry skin types.

Irritation

low

Source

synthetic

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Humectant

Isosorbide

Isosorbide

4.0

Isosorbide is a gentle, plant-based humectant that hydrates skin without stickiness, making it a good alternative to glycerin or hyaluronic acid.

Irritation

low

Source

natural

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Humectant

Japanese Apricot Fruit Water

Prunus Mume Fruit Water

4.0

A gentle, hydrating base ingredient from Japanese apricot fruit that may offer antioxidant and soothing benefits, but research is limited compared to more studied fruit waters.

Irritation

low

Source

natural

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Humectant

Japanese White Birch Juice

Betula Platyphylla Japonica Juice

4.0

A gentle, hydrating sap that soothes skin and provides antioxidant benefits, ideal for sensitive or dry skin types.

Irritation

low

Source

natural

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Humectant

Jeju Volcanic Ferment Complex

Tenacibaculum Jejuense/Oat Bran Extract/Volcanic Ash Extract Ferment Filtrate

4.0

A fermented ingredient that may help hydrate and soothe skin, but research is still early.

Irritation

low

Source

biotech

beautyskincarehumectantsoothing
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Humectant

Jojoba Amino Acids

JOJOBA AMINO ACIDS

4.3

Jojoba Amino Acids are a gentle, plant-based humectant that helps hydrate and support the skin barrier without clogging pores.

Irritation

low

Source

natural

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Humectant

Kefiran

Kefiran

4.0

Kefiran is a gentle, hydrating polysaccharide from kefir that helps skin retain moisture and may support a healthy-looking barrier.

Irritation

low

Source

natural

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Humectant

Kelp Extract

Nereocystis leutkeana extract

4.0

A mineral-rich seaweed extract that hydrates and soothes skin, but its benefits come mostly from its nutrient profile rather than unique active compounds.

Irritation

low

Source

natural

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Humectant

Kelp Juice

Macrocystis Pyrifera Juice

4.0

A mineral-rich seaweed juice that hydrates and soothes skin without clogging pores.

Irritation

low

Source

natural

beautyskincarehumectant
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Humectant

Kelp Juice Extract

Macrocystis Pyrifera Blade/Pneumatocyst/Stipe Juice Extract

4.0

A gentle, hydrating seaweed extract that helps soothe and moisturize skin without clogging pores.

Irritation

low

Source

natural

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Humectant

Kiwi Fruit Beta-Glucan Extract

Actinidia Chinensis (Kiwi) Fruit Extract, Beta-Glucan

4.0

A gentle, hydrating ingredient that combines fruit extract with beta-glucan to help soothe and moisturize the skin.

Irritation

low

Source

natural

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Humectant

Knotted Kelp Extract

ASCOPHYLLUM NODOSUM EXTRACT

4.0

A nutrient-rich seaweed extract that helps hydrate and calm the skin, with antioxidant benefits from coastal minerals.

Irritation

low

Source

natural

beautyskincarehumectantsoothing
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Humectant

Kombucha Ferment Extract

Gluconacetobacter Xylinus Ferment Filtrate Extract

4.0

A gentle, fermented ingredient that hydrates and soothes skin, but its benefits are mostly anecdotal and backed by limited clinical research.

Irritation

low

Source

natural

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Humectant

Konjac Root Extract

AMORPHOPHALLUS KONJAC ROOT EXTRACT

4.2

Konjac root extract is a gentle, plant-based humectant that helps hydrate and soothe the skin without clogging pores.

Irritation

low

Source

natural

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3.8

A gentle, fat-free milk ingredient that hydrates and soothes skin, but its benefits are mild compared to more concentrated actives.

Irritation

low

Source

natural

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Humectant

Lactamide

Lactamide

4.0

A gentle humectant that helps attract moisture to the skin, similar to lactic acid but without the exfoliating effect.

Irritation

low

Source

semi-synthetic

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Humectant

Lactamide MEA

LACTAMIDE MEA

4.0

A gentle humectant that helps skin retain moisture and may improve texture, suitable for most skin types.

Irritation

low

Source

semi-synthetic

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Exfoliant

Lactic Acid

Lactic Acid

4.3

Lactic acid is a gentle AHA that exfoliates dead skin cells while also attracting moisture, making it a great choice for dry or sensitive skin types looking for smoother texture.

Irritation

moderate

Source

natural

beautyskincareexfolianthumectant
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Exfoliant

Lactide

Lactide

4.0

Lactide is a gentle, biodegradable exfoliant that helps smooth skin texture and boost hydration without harsh irritation.

Irritation

low

Source

semi-synthetic

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Humectant

Lactis Proteinum

Lactis Proteinum

3.8

A gentle milk protein that helps hydrate and soften skin, but may not suit those with dairy allergies.

Irritation

low

Source

natural

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Humectant

Lactis Proteinum Extract

LACTIS PROTEINUM EXTRACT

3.8

A gentle milk protein extract that helps hydrate and temporarily smooth the skin, but may not suit those with dairy allergies.

Irritation

low

Source

natural

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Humectant

Lactitol

Lactitol

4.0

Lactitol is a gentle, non-irritating humectant and mild exfoliant that helps hydrate and smooth skin without causing breakouts.

Irritation

low

Source

semi-synthetic

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Soothing agent

Lactobacillus Caulerpa Ferment Filtrate

LACTOBACILLUS/CAULERPA LENTILLIFERA FERMENT EXTRACT FILTRATE

4.0

A gentle, fermented seaweed extract that helps calm irritation and boost hydration without clogging pores.

Irritation

low

Source

biotech

beautyskincaresoothing agenthumectant
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Exfoliant

Lactobacillus Coconut Ferment

LACTOBACILLUS/COCONUT FRUIT JUICE FERMENT FILTRATE

4.0

A gentle, probiotic-based exfoliant that helps smooth skin and support a healthy microbiome without harsh acids.

Irritation

low

Source

biotech

beautyskincareexfolianthumectant
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Humectant

Lactobacillus Collagen Ferment Filtrate

LACTOBACILLUS/HYDROLYZED COLLAGEN FERMENT FILTRATE EXTRACT

4.0

A gentle, fermented collagen ingredient that may help hydrate and support the skin barrier, though research is still emerging.

Irritation

low

Source

biotech

beautyskincarehumectantskin conditioning
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Exfoliant

Lactobacillus Watermelon Ferment

Lactobacillus/Watermelon Fruit Ferment Extract

4.0

A gentle, fermented watermelon extract that provides mild exfoliation and hydration, ideal for sensitive skin.

Irritation

low

Source

biotech

beautyskincareexfolianthumectant
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Humectant

Lactoglobulin

Lactoglobulin

3.8

A gentle milk protein that helps hydrate and temporarily smooth the skin, but may not suit those with dairy sensitivities.

Irritation

low

Source

natural

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Humectant

Lactose

LACTOSE

3.8

Lactose is a gentle milk-derived sugar that hydrates and lightly exfoliates, making it a good option for sensitive or dry skin.

Irritation

low

Source

natural

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