The INKEY List Hyaluronic Acid Hydrating Hair Treatment

DESCRIPTION

What It Does: Provides osmoprotective humectant conditioning with anti-irritant and mild foam-boosting activity.

Why It's Used: Natural-origin multifunctional osmolyte from sugar beet providing hydration, anti-irritancy, and conditioning in virtually every cosmetic category.

How It Works: Quaternary ammonium betaine provides zwitterionic character for water binding via ionic hydration. osmoprotective function at 100–500mm as compatible solute protecting cells from osmotic stress. reduces surfactant irritation by competing with sls for protein binding sites. mild foam enhancement.

Typically Found In: Virtually all categories — moisturisers, shampoos, cleansers

TECHNICAL DETAILS

Primary Category: Functional ingredient – humectant

Secondary Functions: Tewl reduction,skin plumping

Application Areas:

Facial Skincare

Body Care

Hair Care

Beard Care

Color Cosmetics (Makeup)

Dietary/Oral Supplements

Typical Concentration Range: 0.5%–10%

SOURCING & ETHICS

Vegan Status: Yes – from beta vulgaris (sugar beet) molasses

Halal Status: Yes

Source Notes: Synthetic or naturally derived. excellent aqueous solubility.

SKIN COMPATIBILITY

Irritancy Rating: 1/5 – very low

Comedogenicity Rating: 0/5 – non-comedogenic

Sensitivity Concerns: Non-irritating; suitable for all skin types.

Safe for Sensitive Skin: Yes

SAFETY & COMPATIBILITY

Safety Profile: Excellent safety profile. ewg score: 1.

Works Well With: Ceramides,emollients,occlusives,glycerin,hyaluronic acid

Avoid Combining With: No significant incompatibilities

SCIENTIFIC NOTE

Betaine's anti-irritant mechanism for surfactant systems involves competitive protein protection: betaine at high concentrations preferentially interacts with skin proteins, occupying binding sites that would otherwise be occupied by surfactant molecules causing protein denaturation. this competition reduces available protein binding for irritating surfactants, explaining betaine's well-documented ability to reduce sls irritation when co-formulated.

Last Verified: Cosing database,craig betaine osmoprotective review,cir safety assessment

Primary Sources: 2026-03-12

DESCRIPTION

What It Does: Provides osmoprotective humectant conditioning with anti-irritant and mild foam-boosting activity.

Why It's Used: Natural-origin multifunctional osmolyte from sugar beet providing hydration, anti-irritancy, and conditioning in virtually every cosmetic category.

How It Works: Quaternary ammonium betaine provides zwitterionic character for water binding via ionic hydration. osmoprotective function at 100–500mm as compatible solute protecting cells from osmotic stress. reduces surfactant irritation by competing with sls for protein binding sites. mild foam enhancement.

Typically Found In: Virtually all categories — moisturisers, shampoos, cleansers

TECHNICAL DETAILS

Primary Category: Functional ingredient – humectant

Secondary Functions: Tewl reduction,skin plumping

Application Areas:

Facial Skincare

Body Care

Hair Care

Beard Care

Color Cosmetics (Makeup)

Dietary/Oral Supplements

Typical Concentration Range: 0.5%–10%

SOURCING & ETHICS

Vegan Status: Yes – from beta vulgaris (sugar beet) molasses

Halal Status: Yes

Source Notes: Synthetic or naturally derived. excellent aqueous solubility.

SKIN COMPATIBILITY

Irritancy Rating: 1/5 – very low

Comedogenicity Rating: 0/5 – non-comedogenic

Sensitivity Concerns: Non-irritating; suitable for all skin types.

Safe for Sensitive Skin: Yes

SAFETY & COMPATIBILITY

Safety Profile: Excellent safety profile. ewg score: 1.

Works Well With: Ceramides,emollients,occlusives,glycerin,hyaluronic acid

Avoid Combining With: No significant incompatibilities

SCIENTIFIC NOTE

Betaine's anti-irritant mechanism for surfactant systems involves competitive protein protection: betaine at high concentrations preferentially interacts with skin proteins, occupying binding sites that would otherwise be occupied by surfactant molecules causing protein denaturation. this competition reduces available protein binding for irritating surfactants, explaining betaine's well-documented ability to reduce sls irritation when co-formulated.

Last Verified: Cosing database,craig betaine osmoprotective review,cir safety assessment

Primary Sources: 2026-03-12

DESCRIPTION

What It Does: Provides the characteristic cosmetic function of its ingredient class through its molecular chemistry at recommended use concentration.

Why It's Used: Citronellyl methylcrotonate is selected for the specific functional properties of its molecular class — the chemical architecture of citronellyl methylcrotonate delivers the required cosmetic performance through documented interactions with skin biology and formulation matrix.

How It Works: The functional groups interact with formulation components and skin surfaces through h-bonding, ionic association, surface adsorption, or receptor activity as appropriate to the molecular class.

Typically Found In: Cosmetic formulations

TECHNICAL DETAILS

Primary Category: Active ingredient – cosmetic active

Secondary Functions: Skin conditioning

Application Areas:

Facial Skincare

Body Care

Hair Care

Beard Care

Color Cosmetics (Makeup)

Dietary/Oral Supplements

Typical Concentration Range: 0.1%–10%

SOURCING & ETHICS

Vegan Status: Conditional

Halal Status: Yes

Source Notes: Commercially produced for cosmetic use. verify vegan/halal status with supplier.

SKIN COMPATIBILITY

Irritancy Rating: 1/5 – very low

Comedogenicity Rating: 0/5 – non-comedogenic

Sensitivity Concerns: Well-tolerated by most skin types.

Safe for Sensitive Skin: Yes

SAFETY & COMPATIBILITY

Safety Profile: Good safety profile at recommended concentrations. ewg score: 1–2.

Works Well With: Standard skincare actives

Avoid Combining With: No known significant incompatibilities

SCIENTIFIC NOTE

Safety documented in cosing and cosmetic chemistry literature at standard formulation concentrations.

Last Verified: Cosing database,citronellyl methylcrotonate technical review

Primary Sources: 2026-03-22

DESCRIPTION

What It Does: Provides antimicrobial skin conditioning with deodorant activity and preservation system enhancement.

Why It's Used: Multifunctional clean beauty preservation active — ethylhexylglycerin provides antimicrobial, deodorant, and skin conditioning in a single ingredient accepted in most natural cosmetic certification schemes.

How It Works: Glycerol ether provides antimicrobial via bacterial membrane phospholipid disruption. deodorant activity via reduction of underarm lipase enzyme activity (similar mechanism to triethyl citrate). skin conditioning from glycerol humectant component. synergistic with phenoxyethanol and diols.

Typically Found In: Natural preservation systems,deodorants,skin conditioning products

TECHNICAL DETAILS

Primary Category: Functional ingredient – antimicrobial glycerol ether

Secondary Functions: Skin conditioning

Application Areas:

Facial Skincare

Body Care

Hair Care

Beard Care

Color Cosmetics (Makeup)

Dietary/Oral Supplements

Typical Concentration Range: 0.1%–0.5%

SOURCING & ETHICS

Vegan Status: Yes – synthetic

Halal Status: Yes

Source Notes: Commercially produced for cosmetic use. verify vegan/halal status with supplier.

SKIN COMPATIBILITY

Irritancy Rating: 1/5 – very low

Comedogenicity Rating: 0/5 – non-comedogenic

Sensitivity Concerns: Well-tolerated by most skin types.

Safe for Sensitive Skin: Yes

SAFETY & COMPATIBILITY

Safety Profile: Good safety profile at recommended concentrations. ewg score: 1–2.

Works Well With: Standard skincare actives

Avoid Combining With: No known significant incompatibilities

SCIENTIFIC NOTE

Ethylhexylglycerin's deodorant mechanism is pharmacologically identical to triethyl citrate: both inhibit skin surface microbial lipase enzymes that convert odourless triglycerides to odorous free fatty acids. the glycerol ether structure of ethylhexylglycerin, combined with the 2-ethylhexyl chain, provides lipase inhibition similar to ester-based lipase inhibitors from a different chemical class.

Last Verified: Cosing database,schülke sensiva sc 10 technical data,cir safety assessment

Primary Sources: 2026-03-12

DESCRIPTION

What It Does: Hyaluronic acid draws and locks moisture into the skin at multiple depths (surface and deeper layers depending on molecular weight), creating a plumping, smoothing, and hydrating effect.

Why It's Used: It is used because it is endogenous to human skin, making it exceptionally biocompatible and non-irritating. its unparalleled moisture-binding capacity makes it the most effective hydrating ingredient available.

How It Works: Ha binds water molecules through its many hydroxyl and carboxyl groups, creating a gel-like matrix. high molecular weight ha (>500 kda) hydrates the skin surface; low molecular weight ha (<50 kda) penetrates deeper to provide interior hydration.

Typically Found In: Serums,moisturizers,sheet masks,toners,eye creams,lip treatments,dermal fillers (injectable)

TECHNICAL DETAILS

Primary Category: Active ingredient – humectant/hydrator

Secondary Functions: Barrier repair,plumping,anti-aging

Application Areas:

Facial Skincare

Body Care

Hair Care

Beard Care

Color Cosmetics (Makeup)

Dietary/Oral Supplements

Typical Concentration Range: 0.1%–2% (effective at very low concentrations; multi-weight ha provides superior results)

SOURCING & ETHICS

Vegan Status: Yes – biotechnology-derived (microbial fermentation of streptococcus equi or b. subtilis); vegan-certified versions widely available

Halal Status: Yes

Source Notes: Originally extracted from rooster combs; now predominantly produced via biotechnology (bacterial fermentation), which is vegan and more sustainable.

SKIN COMPATIBILITY

Irritancy Rating: 1/5 – very low; one of the gentlest skincare ingredients known

Comedogenicity Rating: 0/5 – non-comedogenic

Sensitivity Concerns: In very dry environments, high-molecular-weight ha on the surface can potentially draw moisture out of the skin if not sealed with an occlusive. apply to damp skin and seal with moisturizer.

Safe for Sensitive Skin: Yes – ideal for all skin types including rosacea, eczema, and post-procedure skin

SAFETY & COMPATIBILITY

Safety Profile: Exceptional safety profile. endogenous molecule – no toxicity concerns. ewg hazard score: 1. safe during pregnancy.

Works Well With: Virtually all ingredients; especially ceramides,glycerin,peptides,retinol (reduces irritation),niacinamide,vitamin c

Avoid Combining With: No significant incompatibilities; high concentrations of alcohol in a formula may reduce its efficacy

SCIENTIFIC NOTE

Hyaluronic acid naturally degrades in skin (half-life ~1–2 days). the skin produces it endogenously, but production decreases with age. multi-molecular-weight ha formulas provide hydration at both surface and deeper skin levels.

Last Verified: Cosing database,cir safety assessment,papakonstantinou et al. (2012) dermato-endocrinology

Primary Sources: 2026-03-12

DESCRIPTION

What It Does: Hydrates skin at multiple depths depending on mw, provides visible plumping from dermal water retention, reduces tewl, and supports barrier integrity and fibroblast proliferation.

Why It's Used: The reference humectant in cosmetics — ha's 1,000× water binding capacity, skin-endogenous origin, and compatibility with all skin types make it the standard against which all humectants are benchmarked.

How It Works: High-mw ha (>1000 kda) films the surface reducing tewl; medium-mw (100–1000 kda) hydrates outer epidermis; low-mw (<50 kda) reaches dermis for plumping. each weight class binds water through carboxylate and amide group h-bonding across the (glcua-glcnac)ₙ disaccharide backbone.

Typically Found In: Hydrating serums,moisturisers,anti-aging

TECHNICAL DETAILS

Primary Category: Functional ingredient – humectant

Secondary Functions: Tewl reduction,skin plumping

Application Areas:

Facial Skincare

Body Care

Hair Care

Beard Care

Color Cosmetics (Makeup)

Dietary/Oral Supplements

Typical Concentration Range: 0.01%–2%

SOURCING & ETHICS

Vegan Status: Yes

Halal Status: Yes

Source Notes: Synthetic or naturally derived. excellent aqueous solubility.

SKIN COMPATIBILITY

Irritancy Rating: 1/5 – very low

Comedogenicity Rating: 0/5 – non-comedogenic

Sensitivity Concerns: Non-irritating; suitable for all skin types.

Safe for Sensitive Skin: Yes

SAFETY & COMPATIBILITY

Safety Profile: Excellent safety profile. ewg score: 1.

Works Well With: Ceramides,emollients,occlusives,glycerin,hyaluronic acid

Avoid Combining With: No significant incompatibilities

SCIENTIFIC NOTE

Ha production by streptococcus zooepidemicus fermentation provides high-purity, animal-free hyaluronic acid at molecular weights 50 kda–3 mda — batch selection determines the intended skin depth target.

Last Verified: Cosing database,hyaluronic acid multi-weight humectant review

Primary Sources: 2026-03-12

DESCRIPTION

What It Does: Exfoliates dead skin cells, attracts and retains moisture, brightens skin tone, and improves texture.

Why It's Used: Dual exfoliant and humectant – uniquely hydrating vs other ahas. gentler and suitable for normal-to-sensitive skin.

How It Works: Disrupts desmosomes to promote exfoliation at low ph. acts as humectant. also stimulates ceramide synthesis at lower concentrations for barrier support.

Typically Found In: Chemical exfoliants,toners,serums,professional peels

TECHNICAL DETAILS

Primary Category: Active ingredient – alpha hydroxy acid (aha)

Secondary Functions: Humectant,brightening,barrier support,ceramide synthesis

Application Areas:

Facial Skincare

Body Care

Hair Care

Beard Care

Color Cosmetics (Makeup)

Dietary/Oral Supplements

Typical Concentration Range: 2%–10% (daily); 20%–90% (professional); active at ph ≤3.9

SOURCING & ETHICS

Vegan Status: Yes – synthetic or fermentation-derived

Halal Status: Yes

Source Notes: Fermentation-derived from carbohydrates or synthetically produced. both l-form and dl-form used.

SKIN COMPATIBILITY

Irritancy Rating: 2/5 – low to moderate

Comedogenicity Rating: 0/5 – non-comedogenic

Sensitivity Concerns: Photosensitizing – spf required. better tolerated than glycolic acid for most skin types.

Safe for Sensitive Skin: Use with caution – spf required

SAFETY & COMPATIBILITY

Safety Profile: Safe at otc concentrations. eu: ≤10% leave-on at ph ≥3.5. mandatory spf advisory.

Works Well With: Niacinamide,ceramides,hyaluronic acid,spf

Avoid Combining With: Retinol in same step; multiple exfoliants simultaneously

SCIENTIFIC NOTE

Lactic acid's role as a natural moisturizing factor (nmf) component makes it uniquely hydrating among ahas. ceramide synthesis stimulation at 2% provides barrier benefits complementing exfoliating activity.

Last Verified: Cosing database,stiller et al. lactic acid review,sccs aha opinion

Primary Sources: 2026-03-12

DESCRIPTION

What It Does: Panthenol deeply moisturizes skin and hair, soothes irritation, accelerates wound healing, strengthens the skin barrier, and improves hair elasticity and shine.

Why It's Used: It is used because it is exceptionally versatile, working in both skin and hair formulations. it is gentle enough for sensitive and post-procedure skin, and converts to the active vitamin b5 within the skin.

How It Works: Panthenol penetrates skin and hair, where it is oxidized to pantothenic acid (vitamin b5), a coenzyme a precursor essential to metabolism. in skin, it acts as a humectant and stimulates fibroblast proliferation. in hair, it coats the shaft, improving manageability.

Typically Found In: Moisturizers,serums,toners,after-sun products,wound healing products,shampoos,conditioners,hair masks,beard care

TECHNICAL DETAILS

Primary Category: Active ingredient – provitamin b5

Secondary Functions: Anti-inflammatory,wound healing,hair conditioning

Application Areas:

Facial Skincare

Body Care

Hair Care

Beard Care

Color Cosmetics (Makeup)

Dietary/Oral Supplements

Typical Concentration Range: 0.5%–5% (typical: 1–3%)

SOURCING & ETHICS

Vegan Status: Yes – synthetically produced

Halal Status: Yes

Source Notes: Commercially synthesized. both d- and dl-forms used in cosmetics; d-panthenol is the biologically active isomer but dl-panthenol is less expensive and widely used.

SKIN COMPATIBILITY

Irritancy Rating: 1/5 – very low; one of the most soothing ingredients in cosmetics

Comedogenicity Rating: 0/5 – non-comedogenic

Sensitivity Concerns: Extremely rare contact allergy; considered one of the safest cosmetic ingredients. suitable for all skin types.

Safe for Sensitive Skin: Yes – ideal for sensitive, reactive, and post-procedure skin

SAFETY & COMPATIBILITY

Safety Profile: Exceptionally safe. ewg hazard score: 1. no significant concerns for irritation, sensitization, or systemic toxicity. safe during pregnancy.

Works Well With: Hyaluronic acid,ceramides,allantoin,niacinamide,centella asiatica,retinol (reduces irritation),glycerin

Avoid Combining With: No known significant incompatibilities

SCIENTIFIC NOTE

Panthenol has demonstrated wound-healing properties in clinical studies, stimulating fibroblast proliferation and migration. its dual humectant and anti-inflammatory action makes it particularly effective in barrier-repair formulations.

Last Verified: Cosing database,cir safety assessment,ebner et al. (2002) skin pharmacology and applied skin physiology

Primary Sources: 2026-03-12

DESCRIPTION

What It Does: Panthenol deeply moisturizes skin and hair, soothes irritation, accelerates wound healing, strengthens the skin barrier, and improves hair elasticity and shine.

Why It's Used: It is used because it is exceptionally versatile, working in both skin and hair formulations. it is gentle enough for sensitive and post-procedure skin, and converts to the active vitamin b5 within the skin.

How It Works: Panthenol penetrates skin and hair, where it is oxidized to pantothenic acid (vitamin b5), a coenzyme a precursor essential to metabolism. in skin, it acts as a humectant and stimulates fibroblast proliferation. in hair, it coats the shaft, improving manageability.

Typically Found In: Moisturizers,serums,toners,after-sun products,wound healing products,shampoos,conditioners,hair masks,beard care

TECHNICAL DETAILS

Primary Category: Active ingredient – provitamin b5

Secondary Functions: Anti-inflammatory,wound healing,hair conditioning

Application Areas:

Facial Skincare

Body Care

Hair Care

Beard Care

Color Cosmetics (Makeup)

Dietary/Oral Supplements

Typical Concentration Range: 0.5%–5% (typical: 1–3%)

SOURCING & ETHICS

Vegan Status: Yes – synthetically produced

Halal Status: Yes

Source Notes: Commercially synthesized. both d- and dl-forms used in cosmetics; d-panthenol is the biologically active isomer but dl-panthenol is less expensive and widely used.

SKIN COMPATIBILITY

Irritancy Rating: 1/5 – very low; one of the most soothing ingredients in cosmetics

Comedogenicity Rating: 0/5 – non-comedogenic

Sensitivity Concerns: Extremely rare contact allergy; considered one of the safest cosmetic ingredients. suitable for all skin types.

Safe for Sensitive Skin: Yes – ideal for sensitive, reactive, and post-procedure skin

SAFETY & COMPATIBILITY

Safety Profile: Exceptionally safe. ewg hazard score: 1. no significant concerns for irritation, sensitization, or systemic toxicity. safe during pregnancy.

Works Well With: Hyaluronic acid,ceramides,allantoin,niacinamide,centella asiatica,retinol (reduces irritation),glycerin

Avoid Combining With: No known significant incompatibilities

SCIENTIFIC NOTE

Panthenol has demonstrated wound-healing properties in clinical studies, stimulating fibroblast proliferation and migration. its dual humectant and anti-inflammatory action makes it particularly effective in barrier-repair formulations.

Last Verified: Cosing database,cir safety assessment,ebner et al. (2002) skin pharmacology and applied skin physiology

Primary Sources: 2026-03-12

DESCRIPTION

What It Does: Stabilises o/w emulsions by reducing interfacial tension, solubilises oils and fragrances in aqueous systems, and wets oil-phase components for improved formulation homogeneity.

Why It's Used: Peg emulsifiers are selected for their precise hlb, broad ph stability (unlike soap emulsifiers that lose function at acidic ph), and compatibility with both anionic and cationic co-ingredients in the formulation system.

How It Works: Peg chain length determines hlb: longer peg = higher hlb = more hydrophilic = better o/w emulsification. at the o/w interface, the peg chain extends into the water phase forming a hydrated steric barrier that prevents droplet coalescence. nonionic character provides ph-independent function across the full cosmetic ph range.

Typically Found In: Emulsions,fragrance solubilisation

TECHNICAL DETAILS

Primary Category: Active ingredient – cosmetic active

Secondary Functions: Skin conditioning

Application Areas:

Facial Skincare

Body Care

Hair Care

Beard Care

Color Cosmetics (Makeup)

Dietary/Oral Supplements

Typical Concentration Range: 1%–10%

SOURCING & ETHICS

Vegan Status: Yes

Halal Status: Yes

Source Notes: Commercially produced for cosmetic use. verify vegan/halal status with supplier.

SKIN COMPATIBILITY

Irritancy Rating: 1/5 – very low

Comedogenicity Rating: 0/5 – non-comedogenic

Sensitivity Concerns: Well-tolerated by most skin types.

Safe for Sensitive Skin: Yes

SAFETY & COMPATIBILITY

Safety Profile: Good safety profile at recommended concentrations. ewg score: 1–2.

Works Well With: Standard skincare actives

Avoid Combining With: No known significant incompatibilities

SCIENTIFIC NOTE

Mixed peg emulsifier systems (e.g., peg-100 stearate + glyceryl stearate) form more cohesive interfacial films than single emulsifiers — the geometric complementarity of the co-emulsifier pair providing better mechanical emulsion stability than either component alone.

Last Verified: Cosing database,peg-40 hydrogenated castor oil peg emulsifier review

Primary Sources: 2026-03-12