astringent

An astringent is a substance that causes the contraction or shrinkage of body tissues, typically by precipitating proteins. In medicine and cosmetics, astringents reduce secretions, relieve inflammation, and can tighten skin or mucous membranes. The term comes from Latin adstringere, meaning to bind or bind tightly.

Mechanism-wise, many astringents rely on tannins or metallic salts. Tannins bind to proteins in skin and mucous membranes, forming insoluble complexes that shrink tissues and decrease secretions. Some astringents coagulate surface proteins to create a temporary barrier, helping to control discharge and irritation.

Common sources include natural plant-derived tannins such as witch hazel, oak bark, gallnuts, and catechu, as well as mineral-based agents like aluminum or zirconium salts (often used in antiseptic or cosmetic products). Astringents may be formulated as liquids, creams, or wipes for topical use.

Medical uses encompass temporary relief of mucous membrane inflammation and minor bleeding, treatment of hemorrhoids or mild diarrhea, and the management of irritation or oozing wounds. They are generally intended for short-term use and should be avoided on open wounds or severely inflamed areas unless advised by a clinician.

In cosmetics, astringents are employed in toners and blemish-control products to reduce oiliness and tighten pores. However, overuse can dry or irritate the skin, especially for those with sensitive or damaged skin, and alcohol-based formulations may sting on broken skin.

See also: tannins, witch hazel, alum, astringent toners.