adstringents

An astringent is a substance that causes tissues to contract or tighten, usually by precipitating proteins. In topical use, astringents dry and constrict mucous membranes and skin, reduce secretions, and can help limit minor bleeding. The compacting effect often arises when polyphenolic compounds, such as tannins, bind to proteins and form protective layers on surfaces.

Types and sources: Astringents can be plant-based or mineral/synthetic. Plant-derived astringents commonly rely on tannins found in oak bark, tea leaves, witch hazel, and certain berries. Mineral and synthetic astringents include aluminum salts (such as alum and aluminum chloride) and zinc salts. Historically, some metal-based agents were used for styptic purposes to stop bleeding.

Uses: In medicine, astringents are used in topical preparations to treat minor skin irritations, insect bites, and hemorrhoidal symptoms, and in mouthwashes or pastes to help manage mouth ulcers and inflammation. In cosmetics, they are employed in toners and oil-control products to tighten pores and reduce shine. They also appear in some wound-care formulations to limit exudate while a temporary protective barrier forms.

Safety and considerations: Astringents can be drying or irritating, especially with sensitive skin or open wounds. They should be used as directed and avoided on large or severely inflamed areas unless advised by a clinician. Prolonged or improper use of metal-based astringents can pose risks of toxicity.

See also: tannins, styptics, topical antiseptics.