Dried venom toxic to mice for at least 27 years. Venom highly hemorrhagic. Hemorrhaging from vascular breakdown occurs in only 6 minutes. Stored venom loses little potency after 17 years. This species probably responsible for more human deaths than any other snake in the U.S. Symptoms following bites include intense burning, vomiting, breathing difficulties, lowered blood pressure, increased heart rate, and secondary gangrene infection.
Death occurs in a high frequency of untreated cases.
For additional information see Ernst, C.H. 1992. Venomous reptiles of North America.