Overview
Antagonists are substances that block or reduce the body’s biological response by binding to cell receptors to stop other chemicals from binding to it, applicable to both natural chemicals produced by the body as well as external chemicals called agonists. In some cases, antagonists can displace chemicals already in the body to prevent ongoing reactions. Beta-blockers are a form of antagonists that block adrenaline from increasing blood pressure and straining the heart. Antihistamines, as the name suggests, block histamine receptors to reduce the itching and swelling that accompany allergic reactions.
Naloxone, or narcan, is one of the most critical antagonists used to prevent overdoses by instantaneously blocking opioid receptors.