adstringentia

Adstringentia are substances that cause contraction of tissues and reduction of secretions. The term derives from the Latin adstringere, meaning to bind together or tighten, and it is used in pharmacology, medicine, and traditional practice to describe agents that dry or tighten mucous membranes and skin.

The primary mechanism of adstringentia involves protein precipitation and cross-linking with mucosal proteins. This creates a denser, less permeable surface, reduces secretions, and can help to diminish minor bleeding. Many adstringents also contribute to a cooling or soothing sensation and may have indirect antiseptic effects through limited tissue damage reduction.

Common sources include natural tannins, such as gallotannins and ellagitannins found in gallnuts, tea, oak bark, and various berries, as well as hydrolyzable tannins like gallic and ellagic acids. Mineral salts—especially aluminum salts (alum) and ferric salts—also function as adstringents. Plant extracts used for their astringent properties include witch hazel and catechu. Synthetic compounds with astringent activity are also employed in some pharmaceutical and cosmetic formulations.

Uses of adstringentia span medical and cosmetic applications. Medically, they are used to treat diarrhea, hemorrhoids, minor mucosal bleeding, and inflammation, and are often formulated as oral rinses or topical solutions. In cosmetics, they are employed as toners and astringent lotions to tighten pores and reduce oiliness.

Safety and considerations: excessive ingestion of tannin-rich adstringents can interfere with iron absorption and cause gastrointestinal upset; contact with sensitive skin can provoke irritation in some individuals. They are generally used with caution and according to appropriate indications and concentrations.