astringent in the Pharmaceutical Industry (əstrɪndʒənt) An astringent is a drug or lotion that causes contraction of body tissues, checks blood flow, or restricts the secretion of fluids. The action of an astringent is characterized by contraction of bodily tissue. An astringent is used to treat bleeding and stop the flow of blood. An astringent is a drug or lotion that causes contraction of body tissues, checks blood flow, or restricts the secretion of fluids.