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

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All UV absorber UV filter abrasive absorbent acne treatment active active ingredient adhesive alkalizing agent amino acid anti-aging anti-androgen anti-cavity anti-cavity agent anti-inflammatory anti-irritant anticaries anticavity agent antidandruff antifungal antimicrobial antioxidant antiperspirant antiplaque astringent barrier repair barrier support barrier-repair barrier-support binder binding agent biotech biotechnology bond-builder botanical botanical extract botanical oil botanical water brightening brightening agent buffer buffering agent cell-communicating ingredient ceramide chelating agent chemical chemical intermediate clay cleanser cleansing cleansing agent colorant conditioner conditioning conditioning agent cooling agent cosmetic cosmetic additive cosmetic colorant cosmetic ingredient cosmetic pigment cosmetic powder cosmetic-texturizer cosmetic-wax cosmetics crosslinking agent delivery agent delivery system denaturant deodorant deodorant agent depigmenting agent depilatory depilatory agent desensitizing agent dye dye intermediate dye precursor dye-intermediate emollient emulsifier enzyme essential oil exfoliant experimental eyelash ferment film former film-former film-forming film-forming agent firming agent fixative flavoring agent formulation fragrance fragrance ingredient functional ingredient gas hair care hair color hair colorant hair conditioner hair dye hair removal hair-care hair-color haircare humectant industrial insecticide intermediate lash lash care lash enhancer lash-and-brow lip care lipid makeup marine extract masking agent microbiome microbiome modulator mineral moisturizer nail care nail-care occlusive oil opacifier opacifying agent optical agent oral care other oxidative dye oxidative dye precursor oxidizing agent pH adjuster pain relief penetration enhancer peptide personal care ph adjuster pharmaceutical pheromone pigment plant oil plasticizer polymer polymer precursor prebiotic prescription-drug preservative preservative booster probiotic processing agent processing aid propellant protein purifying reducing agent retinoid scalp care sebum regulator sebum-regulator self-tanner self-tanning sensory additive sensory agent sensory modifier silicone skin barrier skin barrier support skin conditioner skin conditioning skin conditioning agent skin lightening skin protectant skin-conditioning skin-conditioning agent skin-identical skin-identical ingredient skin-lightening skin-lightening agent skincare solvent soothing soothing agent stabilizer stimulant sunscreen surfactant synthetic synthetic colorant synthetic dye synthetic resin synthetic-colorant texture enhancer texturizer thickener toner uv-absorber uv-filter vasoactive vasodilator viscosity control viscosity controlling viscosity controlling agent vitamin wax

Hair Colorant

P-Phenylenediamine

P-PHENYLENEDIAMINE

2.5

P-Phenylenediamine is a potent hair dye ingredient that delivers long-lasting color but carries a high risk of allergic reactions and skin sensitization.

Irritation

high

Source

synthetic

beautyhair-colorsynthetic-colorant

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