Medical Investigation into the Alleged Poisoning of Crown Prince Sohyeon: Who Killed Crown Prince Sohyeon?

Crown Prince Sohyeon (1612-1645) was the eldest son of King Injo, the 16th monarch of the Joseon Dynasty. Following the defeat in the Manchu Invasion of Korea (1636-1637), he was taken as a hostage to Qing China along with his younger brother, Prince Bongrim (later King Hyojong), and returned to Joseon after eight years in 1645. He died in the same year without ascending to the throne. Allegations of his poisoning emerged based on entries in the Annals of the Joseon Dynasty, leading to widespread acceptance of the poisoning theory and the creation of various cultural works. Although scholars of traditional Korean medicine have published papers suggesting a disease-related death, no thorough medical analysis has been conducted. This study aims to review historical documents to analyze the medical history of Crown Prince Sohyeon and ascertain his cause of death. The study found that Prince Sohyeon began experiencing respiratory, digestive, and urinary symptoms during his time as a hostage in Qing China. The symptoms included fever, cough, dyspnea, thick saliva, thirst, loss of taste, postprandial fatigue, abdominal pain, and dizziness, which persisted even after he returned to Joseon. He eventually succumbed to what appears to have been a respiratory illness characterized by persistent fever and dyspnea. Based on the documented symptoms, it is hypothesized that the cause of death was sepsis. However, given the chronic nature of the symptoms, an underlying autoimmune or metabolic disorder is also suspected as the primary cause, although this cannot be confirmed from the available historical records.