Q

quassin

This bitter crystalline principle of the Jamaican quassia plant is used in cosmetics as a denaturant, and also as an insecticide.

quaternary ammonium salts

A wide variety of these caustic ammonium compounds are used as water repellents, fungicides, emulsyfiers, paper and fabric softeners, antistatic agents and corrosion inhibitors. Their use in cosmetics, especially in hair conditioners and creme rinses, came from the paper and fabric industries.

quaternium-iS

This toxic chemical is more effective against bacteria than against molds and yeasts. One of the most used quaternary ammonium salts, it can cause skin rashes and other allergic reactions due to the hexammonium chloride in it. Lab rats have been murdered with doses of 0.94 to 1.5 g/kg, and mice with doses of 40 to 80 g/kg; guinea pigs had skin reactions at concentrations above 2%.

Quaternium-15 is soluble in water, alcohol and glycols; is compatible with anionics, nonionics, cationics and proteins; has a broad pH range of 4 to 10; and is unstable above 600 C. When used in cosmetic creams, it makes them yellowish in color. It goes under the trade names Dowicil 200, Dowicide Q and Preventol Dl.

quercetin

This flavonoid (don’t confuse it with quercitrin) is present in asparagus, catechu, dill, elder flowers, tarragon, eucalyptus and other plants. It’s the active principle of rutin, and is also known as quercetin-3-rutino side.

quereitrin

This flavonoid (don’t confuse it with quercitin) is present in Roman camomile, eucalyptus, euphorbias, hops, immortelle, tea and witch hazel. It has reportedly cured influenza (in vitro studies on Type A infections), increased the detoxifying activities of the liver and shown anti-inflammatory activity. It’s also used in cosmetics as a natural color.

quillaya bark

The dried inner bark of a South American tree (Quillaja saponaria) has been used by the Indians for many years as a cleanser of the hair and as a detergent. It creates a shampoo with a soft natural lather that’s good for oily scalp and dandruff. It’s also known as soap bark, Panama bark and China bark.

quince seed

The dried seeds of the C’ydonia oblonga are used to thicken and emulsify cosmetics. They’re also used in alcohol- or water-based hairspravs.

quinoline colors or dyes

One type of toxic coal tar color. See colors.