Olaplex No.4P Blonde Hair Hydrating & Brightening Purple Toning Shampoo

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 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: 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: 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: Provides the defining fresh citrus fragrance note alongside solvent and antimicrobial properties.

Why It's Used: The citrus industry's primary fragrance compound and the most abundant terpene in essential oils – limonene provides the clean, universally appealing fresh citrus scent character.

How It Works: D-limonene activates trpv1 mildly at high concentrations. antimicrobial via membrane disruption. solvent for oils and lipophilic compounds. cleaning via emulsification of lipid soils.

Typically Found In: Citrus-scented products,cleaning products,fragrance compounds

TECHNICAL DETAILS

Primary Category: Fragrance component – cyclic monoterpene

Secondary Functions: Skin conditioning

Application Areas:

Facial Skincare

Body Care

Hair Care

Beard Care

Color Cosmetics (Makeup)

Dietary/Oral Supplements

Typical Concentration Range: 0.001%–3%

SOURCING & ETHICS

Vegan Status: Yes – from citrus peel essential oils

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: declared fragrance allergen. oxidises to sensitising compounds (limonene hydroperoxides) on air exposure – use with antioxidant stabilisers. ifra guidelines apply.

Works Well With: Standard skincare actives

Avoid Combining With: No known significant incompatibilities

SCIENTIFIC NOTE

Limonene's sensitisation risk arises not from limonene itself but from its autooxidation products (limonene-1,2-epoxide and limonene hydroperoxides) formed on air exposure. fresh limonene has low sensitisation potential, but air-oxidised limonene's hydroperoxide products are potent skin sensitisers. this explains why oxidation-stabilised formulations (with bht or other antioxidants) are required to manage limonene safety.

Last Verified: Cosing database,ifra standards,bråred christensson et al. limonene oxidation study

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: Deposits a conditioning film on hair and skin through electrostatic attraction to negative cuticle/corneocyte surfaces, reduces hair-on-hair friction for improved combability and detangling, eliminates static charge buildup, and provides anti-frizz humidity resistance.

Why It's Used: Cationic polymers are the primary hair conditioning technology — the permanent positive quaternary ammonium groups provide substantive deposition that resists rinsing, delivering persistent conditioning between washes unlike small-molecule cationic conditioners.

How It Works: At shampoo/conditioner ph 4.5–5.5, hair cuticle carries net negative charge (isoelectric point ph ~3.5). polyquaternium cations undergo electrostatic attraction depositing on the cuticle surface. during rinsing, the deposited polymer film persists from reduced surface-solution equilibrium at low bulk concentration — substantive deposition from favourable interfacial versus bulk partitioning.

Typically Found In: Shampoos,conditioners,leave-in products

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%–3%

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

Different polyquaternium numbers indicate different backbone chemistries: pq-7 (acrylamide/quaternary acrylate copolymer) for leave-on flexibility; pq-10 (hydroxyethylcellulose/quaternary ammonium) for substantive deposition; pq-11 (vp/dimethylaminoethyl methacrylate) for styling fixation.

Last Verified: Cosing database,polyquaternium-7 cationic conditioning deposition review

Primary Sources: 2026-03-12