SNAKE VENOM can destroy the outer membrane of capillary vessels, causing internal bleeding. In some cases they can also activate the blood clotting system, causing clots around the circulatory system. These have the ability to block blood vessels and induce a stroke or heart attack.
From the British NHS:
SNAKE VENOM can destroy the outer membrane of capillary vessels, causing internal bleeding. In some cases they can also activate the blood clotting system, causing clots around the circulatory system. These have the ability to block blood vessels and induce a stroke or heart attack.
Even more convincing