The eastern diamondback rattlesnake is the most dangerous venomous snake in North America. While not usually aggressive, it is large and powerful. Its bite has a mortality rate of 10–20% when untreated. The estimated human lethal dose is 100–150 mg.A doctor described one case in which the symptoms included pain, bleeding from where the snake bit the person, internal pain, bleeding from the mouth, hypotension, a weak pulse, swelling and discoloration of the limb that was bitten.