Kiehl's Ultra Pure High-Potency Serum with 1.5% Hyaluronic Acid

DESCRIPTION

What It Does: Provides gram-negative focused preservation complementary to phenoxyethanol for comprehensive spectrum coverage.

Why It's Used: Phenoxyethanol complement — chlorphenesin's gram-negative and antifungal coverage complements phenoxyethanol's gram-positive activity for full-spectrum preservation at lower individual concentrations.

How It Works: 4-chlorophenol ether glycol disrupts bacterial and fungal membranes. strong gram-negative activity (pseudomonas, e. coli). good candida antifungal activity. used with phenoxyethanol for synergistic broad-spectrum coverage. ph stable 3-9.

Typically Found In: Comprehensive preservation systems,baby products (low concentration)

TECHNICAL DETAILS

Primary Category: Functional ingredient – glycerol ether preservative

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%–0.3%

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: Eu max 0.3% cosmetics. good safety profile. synergistic combination with phenoxyethanol (0.3% pe + 0.1% chlorphenesin often equivalent to 1% pe alone).

Works Well With: Standard skincare actives

Avoid Combining With: No known significant incompatibilities

SCIENTIFIC NOTE

Chlorphenesin + phenoxyethanol synergy operates through a classic spectrum-filling combination: phenoxyethanol provides strong gram-positive antimicrobial activity while chlorphenesin provides gram-negative and antifungal coverage. the combination's minimum inhibitory concentration sum is subadditive (provides equivalent preservation at combined concentrations below what either alone would require) — textbook pharmacological synergy enabling lower total preservative load.

Last Verified: Cosing database,eu preservative annex v,cir safety assessment

Primary Sources: 2026-03-12

DESCRIPTION

What It Does: Adjusts ph to optimal ranges, chelates destabilizing metal ions, provides mild exfoliation at higher concentrations.

Why It's Used: Universal cosmetic ph adjuster and chelating agent. aha exfoliant activity is secondary.

How It Works: As ph adjuster, donates protons. as chelating agent, three carboxylic groups bind divalent metals (ca²⁺, mg²⁺, fe²⁺) preventing oxidative degradation.

Typically Found In: Nearly all cosmetic formulations,brightening products,exfoliants

TECHNICAL DETAILS

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

Secondary Functions: Chelating agent,ph adjustment,preservation enhancement

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: Yes – synthetic or fermentation-derived

Halal Status: Yes

Source Notes: Produced by fermentation of sugars by aspergillus niger. gras (e330). most abundant organic acid in citrus.

SKIN COMPATIBILITY

Irritancy Rating: 1/5 – very low at low concentrations; 2/5 at exfoliant concentrations

Comedogenicity Rating: 0/5 – non-comedogenic

Sensitivity Concerns: Photosensitizing – mandatory spf use. start at low frequency.

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

Three carboxylic acid groups provide multiple proton donation sites and stronger chelation than monocarboxylic ahas. this makes citric acid the preferred cosmetic chelating agent alongside edta.

Last Verified: Cosing database,cir safety assessment,ewg skin deep

Primary Sources: 2026-03-12

DESCRIPTION

What It Does: Glycerin pulls water from the environment and deeper skin layers into the outer skin layer (epidermis), boosting moisture levels and keeping skin soft, smooth, and plump.

Why It's Used: It is used in virtually every moisturizer, serum, and cleanser because it is highly effective at hydrating skin, is well-tolerated by all skin types, and enhances the texture and spreadability of formulations.

How It Works: As a humectant, glycerin forms hydrogen bonds with water molecules, trapping them in the skin. it also reinforces the skin barrier by integrating into lipid structures between skin cells.

Typically Found In: Moisturizers,serums,cleansers,toners,sheet masks,sunscreens,body lotions,shampoos,conditioners

TECHNICAL DETAILS

Primary Category: Humectant

Secondary Functions: Skin barrier support,emollient,solvent

Application Areas:

Facial Skincare

Body Care

Hair Care

Beard Care

Color Cosmetics (Makeup)

Dietary/Oral Supplements

Typical Concentration Range: 1%–30% (typical: 3–10%)

SOURCING & ETHICS

Vegan Status: Yes – plant-derived (coconut, soy, palm) or synthetic

Halal Status: Yes – when plant-derived or synthetic; verify source with supplier

Source Notes: Derived from plant oils via hydrolysis or saponification; synthetic versions also available. palm-derived glycerin carries sustainability concerns.

SKIN COMPATIBILITY

Irritancy Rating: 1/5 – very low; non-irritating at all standard concentrations

Comedogenicity Rating: 0/5 – non-comedogenic

Sensitivity Concerns: Extremely rare allergic reactions; generally safe for all skin types including sensitive and baby skin

Safe for Sensitive Skin: Yes

SAFETY & COMPATIBILITY

Safety Profile: Widely recognized as safe. ewg hazard score: 1. no significant concerns for irritation, sensitization, or toxicity at typical concentrations (up to 50%).

Works Well With: Hyaluronic acid,ceramides,niacinamide,panthenol,urea,peptides,retinol,ahas/bhas

Avoid Combining With: No known incompatibilities at standard concentrations

SCIENTIFIC NOTE

Glycerin is an endogenous skin component found naturally in the stratum corneum. aquaporin-3 channels in keratinocytes facilitate glycerin transport, making it integral to natural skin hydration pathways.

Last Verified: Cosing database,cir safety assessment,ewg skin deep,inci decoder

Primary Sources: 2026-03-12

DESCRIPTION

What It Does: Prevents microbial contamination and spoilage in cosmetic formulations.

Why It's Used: The benchmark cosmetic preservative – eu-permitted up to 1%, effective against virtually all cosmetically relevant microorganisms, and excellent tolerability.

How It Works: Phenol ring provides broad antimicrobial activity via disruption of bacterial and fungal cell membranes and inhibition of enzymatic activity. effective against gram-positive and gram-negative bacteria, yeasts (candida), and molds (aspergillus). activity ph range: 3-9.

Typically Found In: All cosmetic formulations as primary preservative

TECHNICAL DETAILS

Primary Category: Functional ingredient – broad-spectrum preservative

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%–1% (eu max 1%)

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: Eu cosmetics regulation max 1%. sccs assessed as safe at ≤1%. avoid use around eyes in baby products per some country regulations. ewg score: 4.

Works Well With: Standard skincare actives

Avoid Combining With: No known significant incompatibilities

SCIENTIFIC NOTE

Phenoxyethanol's widespread adoption as the primary cosmetic preservative followed the phaseout of parabens from many formulations in the 2000s-2010s. despite having a comparable or better safety profile to parabens, it is often cited in 'free-from' formulations – a consumer perception issue rather than a scientific safety concern.

Last Verified: Cosing database,sccs opinion on phenoxyethanol,cir safety assessment

Primary Sources: 2026-03-12

DESCRIPTION

What It Does: Provides hyaluronic acid hydration in the most formulation-stable and compatible form.

Why It's Used: The standard form of ha used in cosmetics – more stable than free ha, better solubility, and equivalent skin hydration benefits.

How It Works: Sodium salt reduces the polyelectrolyte repulsion of ha chains, allowing better packing in formulations. on skin, sodium ions dissociate and the ha chain unfolds to its full water-binding conformation. provides full ha humectant and barrier benefits equivalent to free ha.

Typically Found In: Hydrating serums,toners,moisturizers,sheet masks,anti-aging products

TECHNICAL DETAILS

Primary Category: Active ingredient – ha sodium salt

Secondary Functions: Equivalent ha hydration,superior stability

Application Areas:

Facial Skincare

Body Care

Hair Care

Beard Care

Color Cosmetics (Makeup)

Dietary/Oral Supplements

Typical Concentration Range: 0.1%–2%

SOURCING & ETHICS

Vegan Status: Yes – bacterial fermentation

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

The sodium salt form of ha has approximately 10% better water solubility than free hyaluronic acid at equivalent molecular weight due to reduced chain-chain electrostatic repulsion from partial sodium counterion screening. this improved solubility enables higher concentration formulations without viscosity issues.

Last Verified: Cosing database,cir safety assessment

Primary Sources: 2026-03-12

DESCRIPTION

What It Does: Provides mineral ion delivery to skin, modulates formulation ionic strength for viscosity and stability optimisation, and supports skin enzyme activity through essential mineral cofactor supplementation.

Why It's Used: Mineral salts are essential formulation ph and ionic strength adjusters — magnesium sulfate specifically provides the mg²⁺ ions that activate transglutaminase crosslinking during sc cornification, supporting barrier formation.

How It Works: Ionic dissociation in aqueous formulation provides free ions that modulate polymer viscosity (ionic strength reduces charge-based thickener swelling), provide mineral nutrition to skin enzymes (ca²⁺ for transglutaminase, mg²⁺ for mgatp phosphotransferases), and adjust osmolality for skin-surface tonicity matching.

Typically Found In: All formulations,mineral skin care

TECHNICAL DETAILS

Primary Category: Active ingredient – mineral / metal active

Secondary Functions: Antimicrobial,sebum regulation,antioxidant enzyme cofactor

Application Areas:

Facial Skincare

Body Care

Hair Care

Beard Care

Color Cosmetics (Makeup)

Dietary/Oral Supplements

Typical Concentration Range: 0.01%–5%

SOURCING & ETHICS

Vegan Status: Yes – mineral

Halal Status: Yes

Source Notes: Mineral/inorganic compound. cosmetic or pharmaceutical grade.

SKIN COMPATIBILITY

Irritancy Rating: 1/5 – very low

Comedogenicity Rating: 0/5 – non-comedogenic

Sensitivity Concerns: Non-irritating at recommended concentrations.

Safe for Sensitive Skin: Yes at recommended concentrations

SAFETY & COMPATIBILITY

Safety Profile: Excellent safety profile at cosmetic concentrations. ewg score: 1–2.

Works Well With: Niacinamide,salicylic acid,other actives

Avoid Combining With: No significant incompatibilities at standard concentrations

SCIENTIFIC NOTE

Mg²⁺ and ca²⁺ are essential cofactors for the sc cornification process — ca²⁺ specifically drives the ca²⁺ gradient across the epidermis (high in outer sc, low in basal layer) that regulates keratinocyte differentiation through ca²⁺-calmodulin signalling.

Last Verified: Cosing database,tetrasodium glutamate diacetate mineral salt formulation review

Primary Sources: 2026-03-12