Hemotoxins

Hemotoxins are toxins that primarily target the circulatory system, including blood coagulation pathways, platelets, and vascular endothelium. The term is often used in toxinology to describe venom components that produce hemorrhage or coagulopathy. Hemotoxic effects are most commonly associated with certain snake venoms, as well as venoms from some spiders, scorpions, and marine organisms. This category is usually contrasted with neurotoxins, which affect the nervous system.

Mechanisms include enzymatic components such as metalloproteases and serine proteases that degrade clotting factors or fibrinogen, phospholipases that disrupt cell membranes and platelet function, and other factors that damage endothelium. Hemotoxins can be procoagulant, causing rapid activation of coagulation and consumption of clotting factors, leading to bleeding risk later; or anticoagulant, impairing clot formation. Hemotoxins can cause local tissue damage and hemorrhage in addition to systemic effects.

Clinical presentation after envenomation ranges from local swelling and tissue necrosis to systemic bleeding, ecchymoses, hypotension, and altered coagulation tests. In severe cases, disseminated intravascular coagulation can occur. Management is supportive and depends on the venom involved; antivenom is the specific treatment for venom-induced coagulopathy when indicated, and may be combined with transfusion of plasma or platelets as needed, along with wound care and monitoring.

In toxinology, the term hemotoxin emphasizes the blood- and vessel-targeting action of certain toxins, particularly those in viperid snakes. It is distinct from hemolytic toxins that lyse red blood cells. Research continues to characterize the specific toxins and their pathways to improve clinical management and antivenom design.