Aug 10, 2009: Are garter snakes venomous?

Garter snakes belong to the Colubridae family of snakes which is one of the largest families of snakes. Garter snakes (Thamnophis sp.) actually are venomous—but you really have to work at it to become envenomated. Published case reports of envenomation involve prolonged bites (e.g. an adolescent male smashing the head of the snake against the skin). The envenomation usually results in swelling of the tissue, local ecchymoses, and occasional formation of hemorrhagic blebs. Care is supportive.

Garter snakes do not have true fangs but have grooved posterior maxillary teeth that may aid in the delivery of their “saliva” into a wound from a bite. Garter snakes have a parotid like gland called Duvernoy’s gland that secretes this “saliva” that contains toxic secretions. The function of these secretions is unclear; however, in some Colubrids, their gland secretion can cause hemorrhage in mice and in others such as the Eastern Hognose snake, can cause neuromuscular blockade in sciatic nerve preparations from frogs. Perhaps this helps with catching dinner…


This question prepared by: Saralyn R. Williams, M.D.  Medical Toxicologist


I am interested in any questions you would like answered in the Question of the Week.  Please email me with any suggestion at


Donna Seger, M.D.

Medical Director

Tennessee Poison Center


Poison Help Hotline: 1-800-222-1222