The Concept of the Humoral Theory in Persian Medicine Publisher



Vaghasloo M A ; Ghanbaryan L ; Fadaei F ; Shirzad M ; Nejatbakhsh F ; Tabrrai M
Source: Journal of Research on History of Medicine Published:2026

Abstract

The humoral theory, as a cornerstone of traditional Unani, Chinese, and Persian medical systems, plays a fundamental role in maintaining health. According to this framework, any excess or deficiency in the body fluids disrupts the body’s balance and triggers disease. This fundamental understanding underscores the pivotal role of the humoral theory in health and disease. Each humor—, be it sanguis, yellow bile, phlegm, or black bile—possesses distinct qualities, characteristics, properties, and consequences. A comprehensive study of these humors was conducted based on traditional resources to ensure the credibility and depth of our research. We reviewed the main textbooks of Persian Medicine (PM), including Avicenna’s Canon of Medicine, and searched the databases including Web of Science, Medline, and Scopus from inception to December 31, 2022, to examine the perspectives of contemporary researchers in this regard. Currently, the closest modern scientific concept to humors is that of molecules, although not all molecules correspond to the traditional definitions of humors. However, the potential applications of the humoral theory in modern integrative medicine are extensive and intriguing. Understanding the humoral theory can provide a unique perspective on health and disease, opening new avenues for research and practice in the global shift toward integrative medicine. The biomolecular and biochemical examples of normal and abnormal humors discussed in Persian Medicine (PM) literature remain unknown. However, many hypotheses can be proposed to open new frontiers in the diagnosis, prevention, and treatment of diseases based on the described characteristics, properties, and consequences of humors. Emerging research in PM over the past two decades supports this claim. © Journal of Research on History of Medicine.