An antihemorrhagic (antihaemorrhagic) agent is a substance that promotes hemostasis (stops bleeing). They may also be known as hemostatic (also spelled haemostatic) agents. Styptics (also spelled stiptics) are a specific type of antihemorrhagic agent that work by contracting tissue to seal injured blood vessels. Antihemorrhagic agents used in medicine have various mechanisms of action. Systemic drugs work by inhibiting fibrinolysis or promoting coagulation. Locally-acting hemostatic agents work by causing vasoconstriction or promoting platelet aggregation.