Twelve hours after the bite, large, blood-filled blisters appear all over the arm. As blood continues to leak out through perforated vessels, the blood pressure drops precipitously. Fortunately, the patient arrives at a hospital and is administered antivenom for rattlesnakes. The antivenom molecules quickly neutralize the venom, and the patient's blood pressure becomes stabilized. The patient will live, but his arm will be permanently scarred and weakened.
Snake venoms are probably the most complicated animal venoms in the world.
Because of variation in these genes, the venom of a single snake species can differ geographically, and even between individuals. Moreover, the particular venom combination can also vary with age in the same snake. This complexity and variability is a headache for physicians treating snakebite victims, because the symptoms are often unpredictable and can differ from patient to patient. But it provides an exciting challenge to those who study snake venoms. In the past two decades, scientists have made significant advances in understanding the pharmacology and toxicology of snake venoms.