Viper venoms typically contain an abundance of protein-degrading enzymes, called proteases, that produce symptoms such as pain, strong local swelling and necrosis, blood loss from cardiovascular damage complicated by coagulopathy, and disruption of the blood clotting system. Death is usually caused by collapse in blood pressure. This is in contrast to elapid venoms that generally contain neurotoxins that disable muscle contraction and cause paralysis. Death from elapid bites usually results from asphyxiation because the diaphragm can no longer contract. However, this rule does not always apply: some elapid bites include proteolytic symptoms typical of viperid bites, while some viperid bites produce neurotoxic symptoms.
Proteolytic venom is also dual-purpose: firstly, it is used for defense and to immobilize prey, as with neurotoxic venoms; secondly, many of the venom’s enzymes have a digestive function, breaking down molecules in prey items, such as lipids, nucleic acids, and proteins. This is an important adaptation, as many vipers have inefficient digestive systems.Due to the nature of proteolytic venom, a viperid bite is often a very painful experience and should always be taken seriously, though it may not necessarily prove fatal. Even with prompt and proper treatment, a bite can still result in a permanent scar, and in the worst cases, the affected limb may even have to be amputated. A victim’s fate is impossible to predict, as this depends on many factors, including (but not limited to) the species and size of the snake involved, how much venom was injected (if any), and the size and condition of the patient before being bitten. Viper bite victims may also be allergic to the venom and/or the antivenom.
This Video was taken while doing some research for Cobra a single drop of this venom (from a Russell’s viper) is dripped onto a petri dish of blood, and in seconds the blood clots into a thick chunk of solid matter.