Unani system of medicine is known for its potential since ancient times. Elite Unani philosophers are credited for proposing consolidated theories and unleashing medical science from the domain of deities and demons. They have set the goal of medicine as prevention as well as cure of disease. Both the health and the disease are described in its own way in respect of functions. Unani philosophers contemplated that human body is composed of three basic components; solid (body organs), liquid (humours), gaseous (pneuma). The liquid substances of the body are collectively called as Akhlāṭ (humours). Every humour serves some specific and general functions. Basically, these are approximate principle for nutrition of organs. Black bile is one among the humours responsible for the health and the disease in the body. A right proportion of black bile keeps the body healthy, but disproportion of it causes deadly diseases. It is a fact that everything in the body is directly, or indirectly related with the four humours. In present study, a comprehensive explanation of black bile is given. Much emphasis is given on the genesis of normal and abnormal black bile. All factors responsible for alteration in black bile are enumerated thoroughly in the study. It is believed that the present work would help the reader in better understanding of the concept of black bile and their effect on the human health.
Methodology: Relevant literary material is collected from classical books of Unani system of medicine. Present work is an attempt to analyse and systematize collected relevant literary information regarding the concept of black bile and their effect on the human health.
Interpretation and conclusion: From the contents of literature; it is clear that black bile is the sediment of normal blood. It is the last to arise and receives the coarse, most meagre share of nutrients and has a retentive virtue, a cooling, drying, astringing, precipitating, condensing, solidifying effect on the metabolism necessary for building the bones, teeth and all dense, solid structures of the body. The black bile is an essential humour that keeps the body healthy. Therefore; an optimal level of black bile plays an important role in maintenance of health as other three humours. An imbalance in quality and quantity of black bile is responsible for the diseases.
Key words: Akhlāṭ Arba‘a (humours); Sawdāʼ (black bile); health; disease.