An astringent is a substance that causes a tightening or contracting of soft tissues. The word "astringent" comes from the Latin word "adstringere," which means "to bind fast". Astringents can be used for various purposes, including in medicine and skincare. In medicine, astringents cause constriction or contraction of mucous membranes and exposed tissues and are often used internally to reduce discharge of blood serum and mucous secretions. This can happen with a sore throat, hemorrhages, diarrhea, and peptic ulcers. Externally applied astringents, which cause mild coagulation of skin proteins, dry, harden, and protect the skin. People with acne are often advised to use astringents if they have oily skin. In skincare, astringents are used to cleanse and tighten pores, remove oil, and reduce the appearance of pores. Some common examples of astringents in skincare include alcohol and witch hazel. Tannins, which are types of antioxidants present in certain foods such as berries, grapes, and teas, are also astringents. It is important to note that astringents can be very drying for the skin, so alcohol-based and chemical-based astringents should be avoided if you have dry or sensitive skin. If you have acne and dry skin, an astringent may further irritate breakouts, leading to peeling and additional redness. Instead, try a hydrating toner or oil-free moisturizer, or ask a dermatologist for recommendations.