Astringents are substances that:

Astringents: They are substances that precipitate proteins. Eg: Tannic acid and tannins Tannic acid is present in many plants but is generally obtained from nutgalls of oak. Tannins are found in tea, catechu, nutmeg, areca nut (betel nut), etc. They denature proteins forming protein tannate. Alcohol or Ethanol and methanol are good astringents at 50-90% concentration. othe eg: are alum, acacia, sage, yarrow, witch hazel, bayberry, distilled vinegar, very cold water, and rubbing alcohol. Mild astringents relieve such minor skin irritations as those resulting from superficial cuts; allergies; insect bites; anal hemorrhoids ESSENTIALS of medical PHARMACOLOGY SIXTH EDITION -KD TRIPATHI Page:887