Ingredient Dictionary

Best

idebenone

A synthetic antioxidant similar to coenzyme Q10. Idebenone got a lot of press as the best... Read More »

Categories: Antioxidants

Best

Ilex paraguariensis

See yerba mate extract

Categories: Antioxidants, Anti-Irritants

Poor

Illicium vernum

See anise

Categories: Irritants, Fragrance: Synthetic and Fragrant Plant Extracts, Antioxidants, Antibacterial/Anti-Acne

Average

imidazolidinyl urea

Considered a weaker preservative than its "cousin" diazolidinyl urea because it is active against... Read More »

Categories: Preservatives

Good

inactive ingredient

The list of inactive ingredients is the part of an ingredient label that is not regulated by the... Read More »

Categories: Miscellaneous

Best

inositol

Major component of lecithin that may have water-binding properties for skin. It is not a vitamin,... Read More »

Categories: Skin-Identical/Repairing Ingredients

Average

insulinlike growth factor (IGF)

Stimulates fat cells and connective tissue cells. Read More »

Categories: Cell-Communicating Ingredients

Best

intercellular matrix

"Mortar" that holds layers of skin cells together, creating a contiguous natural, external barrier.... Read More »

Categories: Skin-Identical/Repairing Ingredients

Average

interleukin (IL)

Stimulates growth of white blood cells. Read More »

Categories: Cell-Communicating Ingredients

Poor

Inula helenium

See elecampane

Categories: Irritants, Plant Extracts

Good

iodopropynyl butylcarbamate

A synthetic preservative that is typically used in concentrations of 0.1% or less. It is very... Read More »

Categories: Preservatives

Poor

Iris florentina extract

See orris root

Categories: Irritants, Plant Extracts, Fragrance: Synthetic and Fragrant Plant Extracts

Good

Irish moss extract

Type of red algae. Read More »

Categories: Antioxidants, Thickeners/Emulsifiers, Plant Extracts, Emollients

Good

iron oxides

Compounds of iron that are used as colorings in some cosmetics. They also are used as a metal... Read More »

Categories: Coloring Agents/Pigments

Average

iron powder

Iron powder is, as the name states, a powdered versoin of the mineral iron. A natural ingredient, it's used as an opacifying agent in cosmetics. Read More »

Categories: Absorbent

Good

isobutyl acetate

See solvent

Categories: Miscellaneous

Good

isobutylparaben

See parabens

Categories: Preservatives

Average

isocetyl salicylate

See sodium salicylate

Categories: Miscellaneous

Good

isododecane

Hydrocarbon ingredient used as a solvent. Isododecane enhances the spreadability of products and... Read More »

Categories: Miscellaneous

Best

isoflavone

Plant estrogen with potent antioxidant properties (Source: Free Radical Biology and Medicine,... Read More »

Categories: Antioxidants, Plant Extracts

Good

isohexadecane

Used as a detergent cleansing agent, emulsifier, and thickening agent in cosmetics. Read More »

Categories: Thickeners/Emulsifiers, Surfactants/Detergent Cleansing Agents

Good

isoleucine

See amino acid

Categories: Antioxidants, Skin-Identical/Repairing Ingredients

Good

isononyl isononanoate

An ester that functions as a skin-conditioning agent. Occurs naturally in cocoa and lavender oil. Read More »

Categories: Emollients

Good

isoparaffin

See paraffin

Categories: Thickeners/Emulsifiers

Poor

isopropyl alcohol

See alcohol

Categories: Irritants

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About the Experts

Paula Begoun is the best-selling author of 20 books on skin care and makeup. She is known worldwide as the Cosmetics Cop and creator of Paula's Choice. Paula's expertise has led to hundreds of appearances on national and international television including:

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The Paula's Choice Research Team is dedicated to helping you find the absolute best products for your skin, using research-based criteria to review beauty products from an honest, balanced perspective. Each member of the team was personally trained by Paula herself.

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