Astringent. An astringent is a pharmaceutical medication used to stop normal, minor bleeding problems. Alum, which stings, is a fine example. You can find it in a pharmacy as a styptic pencil or something similar. Astringents used by a non medical individual should only be used on minor scratches. Anything deep or resists clotting, should be seen by a professional in case an artery or stitches are required.