There was a viking ( I think) who cut his leg on the severed head of one of his enimes. It got infected and he died.
There is a display in the museum in Dornoch that tells the story.
"Sigurd the Mighty (circa 900) - Sigurd Eysteinsson was a Viking noble who was a leader of the Viking occupation of northern Scotland. He was involved in some sort of conflict with a local chieftain named Mael Brigte the Bucktoothed, and the two agreed upon a battle with forty men a side to settle their differences. Sigurd brought eighty, defeated the locals, and beheaded Mael. He then triumphantly fixed Mael's head to his saddle and galloped off presumably screaming about his victory in a suitably bad-bottom Viking manner. Unfortunately the severed head's buck tooth scratched his leg, creating a wound which became infected, and eventually led to his death. So yeah, Sigurd the Mighty is the only man in history to have been killed by his enemy's severed head."