A small duct connects each fang to a large venom gland on each side of the head, underneath the eye. The teeth are hinged at their base, and swing inwards when the mouth is closed, and lie within the protective sheath. It is over in a second. Gaping moccasin with fang sheaths still folded. In their book Venomous Reptiles , Minton and Minton table the venom yield for an average adult moccasin at 100 - 150 mg, and the estimated lethal dose for an adult at 100 mg.
Fatalities are uncommon, but the potential is there.
A non-fatal bite can still be excruciatingly painful and potentially crippling. Cottonmouth venom is haemotoxic, affecting the circulatory system and body tissues. It breaks down and necrotizes even hard muscle tissues. There is severe swelling around the bite, sometimes affecting the entire appendage. Gangrene oftentimes necessitates the amputation of fingers, toes, and even limbs.