Skin Care Cosmetics Ingredients Glossary

Q

quaternium-15. Formaldehyde-releasing preservative used in cosmetics. It can be a skin sensitizer, as can all preservatives.

quaternium-18 hectorite. Used as a suspending agent and also has emulsifying properties.

quercetin. Flavonoid pigment that has antioxidant and anti-inflammatory properties. Quercetin has antihistamine properties when taken internally via foods (e.g., apples, red wine, and buckwheat natural sources) or supplement form. See bioflavonoid.

quercus. See oak root extract.

Quercus infectoria extract. See oak root extract.

quillaja extract. Extract of the Chilean soap bark tree. It contains a good amount of saponins, which have cleansing, antimicrobial, and water-binding properties for skin. See saponin.

quince seed. Used as a thickening agent in cosmetics, but also has skin-constricting properties and may cause skin irritation.

quinoa oil. Derived from quinoa grain, it may have antifungal properties. It may also have emollient properties for skin, but there is little research showing this to be the case.