faex. A type of yeast. See yeast.

Fagus sylvatica extract. See yeast.

farnesol. Extract of plants that is used in cosmetics primarily for fragrance. A few animal studies and some in vitro research investigated farnesol’s antibacterial properties (Source: Chemotherapy, July 2002, pages 122–128), and it may also have some antioxidant properties (Source: Journal of Bacteriology, September 1998, pages 4460–4465), but there is no research showing it has any benefit on skin.

farnesyl acetate. See farnesol.

fatty acid. Substance typically found in plant and animal lipids (fat). Fatty acids include compounds such as glycerides, sterols, and phospholipids. They are used in cosmetics as emollients, thickening agents, and, when mixed with glycerin, cleansing agents. Fatty acids are natural components of skin and are components of a complex mixture that makes up the outermost layer that protects the body against oxidative damage (Sources: Free Radical Research, April 2002, pages 471–477; and Journal of Lipid Research, May 2002, pages 794–804). Fatty acids can help supplement the skin’s intercellular matrix. See natural moisturizing factor (NMF).

fatty alcohol. Made from fatty acids; fatty alcohols are used in cosmetics as thickening agents and emollients. They are not drying or irritating forms of alcohol. See fatty acid.

FD&C. Type of coloring agent. According to the FDA, when FD&C is followed by a color, the color is certified as safe for use in food, drugs, and cosmetics.

fennel oil. Volatile, fragrant oil that can cause skin irritation and sensitivity. See fennel seed extract.

fennel seed extract. Can have antioxidant properties, but on skin it can be a skin irritant and photosensitizer (Source: http://www.naturaldatabase.com).

ferric ammonium ferrocyanide. Inorganic salt of ferric ferrocyanide. See ferric ferrocyanide.

ferric ferrocyanide. Also known as Iron Blue, a coloring agent used in cosmetic products, including those designed for use around the eye. Permanently listed (since 1978) by the FDA as safe, although the EPA considers it toxic when found in water systems.

Ferula galbaniflua. See galbanum.

feverfew extract. Can be very irritating to the skin and can trigger allergic reactions (Source: Contact Dermatitis, October 2001, pages 197–204). However, when taken orally it has been shown to relieve migraines and have anti-inflammatory properties (Source: http://www.naturaldatabase.com).

fibroblast growth factor (FGF). Within the body, stimulates growth of the nervous system and bone formation. See human growth factor.

fibronectin. Type of protein found in the skin’s intercellular matrix, similar to collagen and elastin. Fibronectin’s deterioration from sun damage and other factors is an element in skin aging and wrinkling. As is true for all proteins, regardless of their origin, it is probably a good water-binding agent for skin. However, applying fibronectin topically on skin doesn’t help reinforce or rebuild the fibronectin in your skin.

Ficus carica fruit extract. See fig.

fig. Fruit that contains psoralens, which are compounds that may cause photodermatitis. Topical application can cause contact dermatitis. Latex from the fruit is used topically to treat skin tumors and warts, which has nothing to do with anti-aging (Source: http://www.naturaldatabase.com).

Filipendula glaberrima. Also known as Nakai, the root of this plant extract has been shown in vitro to be not only a potent antioxidant but also able to inhibit the expression of collagen-depleting MMP-1 when applied to human fibroblast cells (Source: Journal of Cosmetic Science, January/February 2007, pages 19-32). See matrix metalloproteinases.

Filipendula rubra. See meadowsweet extract.

film-forming agent. Large group of ingredients that are typically found in hair-care products, but that are also widely used in skin-care products, particularly moisturizers. Film-forming agents include PVP, acrylates, acrylamides, and copolymers. When applied they leave a pliable, cohesive, and continuous covering over the hair or skin. This film has water-binding properties and leaves a smooth feel on skin. Film-forming agents can be weak skin sensitizers (Source: Contact Dermatitis, October 2007, pages 242–247).

fir needle oil. Volatile, fragrant oil that can cause skin irritation and sensitivity.

fireweed extract. Extract from the Epilobium angustifolium plant; also known as willow herb. See Epilobium angustifolium extract.

fish cartilage extract. May have water-binding properties, but there is no research showing that this has any benefit for skin.

flavonoid. See bioflavonoid.

flax. Plant source of linen and edible seeds. Flax seeds and seed oil have antioxidant properties (Source: Biofactors, 2000; volume 13, pages 179–185). The seeds are also a source of linolenic acid. See linolenic acid.

flaxseed oil. From seeds of the flax plant; a source of fatty acids, particularly omega-3. See flax.

floralozone. One of a number of synthetic fragrant components.

Foeniculum vulgare extract. See fennel oil and fennel seed extract.

folic acid. Part of the B-vitamin complex; when taken orally, it is a good antioxidant. That benefit has not been demonstrated when it is applied topically on skin.

formaldehyde-releasing preservative. Common type of preservative found in cosmetics (Source: Contact Dermatitis, December 2000, pages 339–343). Despite some claims, there is no higher level of skin reaction to formaldehyde-releasing preservatives than to other preservatives (Source: British Journal of Dermatology, March 1998, pages 467–476). In fact, there is a far greater risk to skin from a product without preservatives, because of the contamination and unchecked growth of bacteria, fungus, and mold that can result if no preservatives are used. However, there is concern that when formaldehyde-releasing preservatives are present in a formulation that also includes amines, such as triethanolamine (TEA), diethanolamine (DEA), or monoethanolamine (MEA), nitrosamines can be formed, and nitrosamines are carcinogenic substances that can potentially penetrate skin (Source: Fundamentals and Applied Toxicology, August 1993, pages 213–221). Whether or not that poses a health risk of any kind has not been established. See preservatives.

fragrance. One or a blend of volatile and/or fragrant plant oils (or synthetically derived oils) that impart aroma and odor to products. These are often skin irritants (Sources: Dermatology, 2002, volume 205, number 1, pages 98–102; Contact Dermatitis, December 2001, pages 333–340; and Toxicology and Applied Pharmacology, May 2001, pages 172–178). See volatile oil.

frankincense extract. Fragrant component used in skin-care products; it can be a skin irritant. There is no research showing frankincense has any benefit for skin (Sources: http://www.herbmed.com; and http://www.naturaldatabase.com).

free-radical damage. Occurrence that takes place at an atomic level and is a complex physiological process. Molecules are comprised of atoms. Atoms comprise all matter in the universe. Atoms are made up of protons, neutrons, and electrons. Electrons occur in pairs, and when an element only has a few paired electrons it can easily become unstable. Oxygen and oxides are primary examples of potential unstable elements in our environment. When oxygen interacts with skin (and because the air we breathe is 20% oxygen, that happens all the time), it almost always loses one of its electrons. This oxygen molecule, which now is minus one electron, is a free radical. Because it is now unstable the oxygen molecule quickly finds another electron, and it does this by taking an electron from another molecule in the skin, which is usually a healthy substance such as collagen, skin-identical substances, or antioxidants in the skin which have lots of electrons to spare. Once those substances are robbed of all their electrons they break down and are destroyed. Oxygen molecules (or other potential free radical substances) attempting to repair themselves in this way trigger a cascading event termed free-radical damage. The reactions that cause free-radical damage take place in mere fractions of a second. Antioxidants are substances that prevent oxidative damage from being triggered. See antioxidant.

The primary causes of free-radical damage on skin are sunlight, pollution, air, cigarette smoke, herbicides, and solvents (such as alcohol). Antioxidants are a way to reduce and potentially neutralize free-radical damage (Sources:Journal of Clinical Pathology, March 2001, pages 176–186; and Drugs and Aging, 2001, volume 18, number 9, pages 685–716).

fructose. Often called fruit sugar, fructose is a type of sugar composed of glucose. It has water-binding properties for skin. See water-binding agent.

fruit acid. See sugarcane extract.

Fu ling. See Poria cocos extract.

Fucus vesiculosus extract. See bladderwrack extract.

fuller's earth. Mineral substance that is similar to kaolin (a clay). Composed mainly of alumina, silica, iron oxides, lime, magnesia, and water, it is used as an absorbent and thickening agent in cosmetics.

fumaric acid. Naturally occurring acid that has been proven effective for systemic and topical treatment of severe psoriasis vulgaris (Source: Journal of Investigative Dermatology, February 2001, pages 203–208); however, it can also cause serious skin irritation (Source: Dermatology, 1994, volume 188, number 2, pages 126–130). In small amounts it can be used as a pH adjuster in cosmetics.