Common skin care ingredients -- A

Acetate: an acetic acid salt; the word that follows or precedes acetate on an ingredient list determines the function.

Acetone: solvent commonly used in fingernail polish removers and toners; can be drying and irritating depending on concentration.

Acetylated Lanolin Alcohol: An alcohol that is not drying. Helps soften skin; is highly comedogenic (causes blackheads and/or whiteheads).

Acrylates Copolymer: active ingredient in an oil-absorbing gel, such as Clinac O.C.

Acrylates/Octylpropenamide Copolymer: creates a water-repelling base/matrix for cosmetics claiming water-proof properties.

Alcohol SD-40: sometimes listed as SD Alcohol 40 and synomymous with alcohol SDA-40, it is a high grade purified cosmetic alcohol. Evaporates instantly, so it is used as a vehicle to transport important ingredients to the skin's surface and then leave them there; gentler to the skin than ethyl (rubbing) alcohol. May help kill bacteria.

Algae/Seaweed Extract: an emollient, restoring moisture content to skin; claims to have antioxidant properties.

Allantoin: a botanical thought to have skin calming properties; possibly reduces irritation.

Alpha Hydroxy Acid: an active ingredient derived from fruit acids. Helps exfoliate the top layers of the epidermis: promotes moisture restoration and helps penetration of other ingredients; highly sought after for use in anti-aging and bleaching skin care products. May irritate the skin especially if overused. Buffering the pH helps make them less irritating to the skin, but also reduces exfoliating effect. AHA's include: citric acid (citrus fruits), glycolic acid (sugar cane), lactic acid (milk), and the less common AHAs used in cosmetics malic acid (apples) and tartaric acid (wine). AHAs increase sun sensitivity due to their exfoliant behavior.

Alpha Lipoic Acid: an antioxidant; is both water and fat soluble so it can protect many areas of a cell. Also, has anti-inflammatory properties.

Alum: usually in crystal or powder form; has strong astringent properties; used in stypic sticks, popular with men who often nick themselves shaving.

Ascorbic Acid: vitamin C; an antioxidant and stimulant of collagen synthesis by skin cells (fibroblasts). Can also have skin lightening effect in certain preparations. Only L-ascorbic acid (as opposed to D-ascorbic acid) is effective.

Ascorbyl Palmitate: fat-soluble vitamin C derivative. Good antioxidant but less effective than vitamin C for stimulating collagen synthesis.

Avobenzone: UV radiation blocker used in sunscreens. Also, sold under brands Parsol, Eusolex, and Escalol (see avobenzone fact-sheet )