Common skin care ingredients and their purpose.

Acetate: an ester of acetic acid; any word that's combined with acetate in an ingredient list determines its function.

Acetone: the simplest ketone frequently used in toners. Acetone can cause irritation and drying if its concentration is high.

Acetylated Lanolin Alcohol: a non-drying alcohol that softens skin. However, it's also known for causing blackheads and whiteheads.

Acrylates: make cosmetics water resistant. This ingredient is also called Octylpropenamide Copolymer.

Alcohol SD-40: is a highly refined alcohol used in cosmetics. Because it evaporates very quickly, it's often used as a way to quickly transport ingredients to the skin's surface to kill bacteria. Compared to ethyl (rubbing) alcohol, SD-40 is gentler on the skin.

Algae Extract: is used as an antioxidant; restores skin's moisture.

Allantoin: helps heal and calm skin irritations and is botanical in nature.

Alpha Hydroxy Acid (AHA): it's an organic acid taken from fruit and is used widely in anti-aging skin care products. It exfoliates and helps other ingredients such as moisturizers, to penetrate through the skin more effectively. Always use products containing AHAs in combination with sunscreen as they make your skin more susceptible to sun damage.

Alpha Lipoic Acid: has anti-inflammatory benefits, plus its water and fat soluble to protect skin cells.

Alum: an astringent that's often used in after-shave products to treat nicks or razor cuts caused by shaving.

Ascorbic Acid: the medical name for vitamin C. L-ascorbic acid is often used in skin lightener products and anti-aging products because it stimulates collagen production.

Beeswax: derived from the natural honeycombs, is often used in moisturizing products such as lip balms, foot creams and body creams.

Benzoyl Peroxide: powerful antibacterial agent that helps kill acne by drying P. acne bacteria on the skin. Peroxide is also used to sanitize open wounds. Can be irritating.

Beta Hydroxy Acid: an oil-soluble organic acid used in exfoliators and acne-acne treatments.

Boric Acid: an antibacterial agent used in skin care products to give them a longer shelf life.

Caffeine: a stimulant present in coffee, tea and soda beverages, is also useful to soothe puffy eyes.

Camphor: an anti-infective agent with a unique taste and smell, cools and refreshes itchy skin.

Cellulose: is derived from the walls of plants and used as an emulsifier and thickener in skin care products.

Collagen: the main epidermal protein, supports the skin, bones, tendons, cartilage and connective tissue. Collagen is added to topical creams for its moisturizing benefits.

Cyclomethicone: a type of silicone that provides luster and smoothness to skin care creams and cosmetics.

Dimethicone: used as a sealant in scar rehabilitation to smooth skin texture and provide moisture.

Elastin: a protein in the dermis (the layer of the skin beneath the epidermis). Elastin is responsible for skin elasticity and firmness. When it's topically applied it has moisturizing effects.

Ethyl Alcohol: refined alcohol made from grain that's often used in medicines, cleaning products, fragrances and astringents and toners. As it dries skin very quickly, moisturizers are always required after application.

Fragrance: a pleasant distinctive aroma, usually blended from natural essential oils and concentrated chemicals distilled from plants.

Glycerin: this liquid derivative of biodiesel production is used in cosmetics, liquid soaps, dynamite, inks and lubricants to lock-in hydration and keep skin moisturized, but it can also clog the pores.

Glycol Stearate: an emollient and emulsifier often used in body skin care products and shampoos to achieve a luminescent appearance.

Grape Seed Extract: a botanical extract known to increase the effectiveness of vitamin C by acting as a vehicle and a restorer of oxidized vitamin C.

Green Tea Extract: this derivative from decaffeinated green tea contains "catechins"; which are effective antioxidants known to help to prevent cancer.

Hyaluronic Acid: also known as "cyclic acid", is a powerful moisturizing agent.

Hydroquinone: a skin lightening agent. Two-percent concentrations are commonly found in over-the-counter lighteners; while prescription bleaching products have higher concentrations.

Isopropyl Palmitate: a skin softening ingredient that comes from palm and coconut oil, however it's known to cause blackheads and whiteheads.

Jojoba Oil: natural oil taken from the seeds of the Simondsia Chinesis, a desert shrub. It's very similar to natural human oil secretions so it's non-greasy.

Kaolin: also called China Clay, fine clay that's white in color. Kaolin is often used in facial masks and powders that absorb oil.

Lactic Acid: used in chemical peels to hydrate, moisturize and strip away dry, flaky skin cells.

Lanolin: this oily substance comes from sheep and is commonly used in bath oils and hand creams to provide extra moisture. In rare cases it can irritate the skin and cause a skin allergy.

Lecithin: this antioxidant from nature is primarily derived from soybeans. It's a natural emollient and emulsifier that helps to soften and replenish the skin.

Linoleic Acid: a vital fatty acid that fattens skin cells.

Liposomes: tiny spheres that transfer hydrating ingredients to skin cells.

Methyl Gluceth: attracts moisture and reduces skin dryness.

Mineral Oil: clear, unscented oil derived from petroleum hydrocarbons. Mineral oil is widely used in cosmetics to remove makeup, grease and excess oil from the skin.

Octyl Methoxycinnamate: used as an ingredient in non-PABA chemical sunscreens. May cause skin irritation in some cases.

Octyl Palmitate: often used as an alternative to mineral oil for its similar properties.

Octyl Salicylate: a sunburn and anti-bacterial preventative.

Oxybenzone: a UVB blocker used in sunscreen.

PABA: stands for para-aminobenzoic acid; blocks UVB sunlight.

Parabens: artificial chemicals, used as preservatives in cosmetics.

Petrolatum: Vaseline's #1 ingredient is commonly used in creams to soften and soothe the skin.

Retinol: a fat-soluble vitamin A. Retinol is crucial for good vision and healthy skin, but in high concentrations it may cause skin irritations.

Retinal: also called "retinaldehyde" and a derivative of vitamin A. Retinal is one of the molecules responsible for light sensitivity.

Rose Hips: this botanical extract from wild roses is rich in vitamin C.

Salicylic Acid: a mild beta hydroxy acid that's used as a safe exfoliant in chemical peels.

Silica: silicon dioxide; absorbs oil rapidly.

Silicone: a non-metallic chemical component to keep the skin healthy and refreshed; helpful in diminishing the appearance of hypertrophic scars.

Silk Powder: a natural fiber added to cosmetic products to give them their fine texture and to absorb oil.

Silk Proteins: used in some eye creams to prevent dehydration.

Sodium Bicarbonate: commonly called "baking soda". This neutral acid raises skin PH levels.

Sodium Borate: commonly called "borax"; works as a preservative in cosmetics.

Sorbic Acid: a water-soluble acid and preservative.

Sulfur: this essential mineral module of vitamin B, kills bacteria causing acne. Found in many over-the-counter topical acne medications.

Titanium Dioxide: a chemical substance used in sunscreen products; blocks both UVA and UVB sunrays.

Vitamin A: a fat-soluble vitamin that keeps skin hydrated. Vitamin A is used in skin care products because it improves aging skin and firms skin texture. It can also dry out acne, but it makes skin sun sensitive.

Vitamin C: a water-soluble vitamin used in cosmetic creams, topical and oral medicines to boost collagen synthesis.

Vitamin D: a fat-soluble vitamin required for tooth and bone structure. It's used in some prescription medicines to treat psoriasis.

Vitamin E: an oil-soluble antioxidant and emollient used in deodorants and hair care products to soften skin and hair.

Water: or H20, a colorless tasteless liquid used in all skin care products.

Witch Hazel: an effective astringent extracted from the leaves and bark of the Hamamelis Virginnia plant. It has botanical properties, helps improve acne, awakens puffy eyes and reduces excess oil on the skin.

Xanthan Gum: an emulsifier and thickener.

Zinc Oxide: this composite that increases immune function has anti-irritant properties so it's commonly used in diaper rash creams and sunscreen products to prevent UV light from contacting the skin.