Traces of proteins found on letters he wrote in 1457 and 1475 suggest he suffered from respiratory and skin diseases and could have had a condition known as hemolacria, which is when blood gets mixed in with tears. The findings add one more facet to the ruler's spine-chilling reputation.

It is suspected that prince Vlad suffered an erythropoiethic porphiria, which could be the reason for the development of certain peculiar characteristics of the vampires.