Diagnosis of diseases and treatment in Siddha system of Medicine is unique in that it is holistic in approach and the diagnosis involves the study of person as a whole as well as his/her disease. It is made taking in to account of many factors like the personality, physical condition, physiological constitution, mental frame, age, sex, race, diet, appetite, habits, environment, the meteorological consideration, habitat etc.
Identification of causative factors is through the examination of pulse, urine, eyes, study of voice, colour of body, tongue and the status of the digestive system. The system has worked out detailed procedure of urine examination which includes study of its colour, smell, density, quantity and oil drop spreading pattern. This means the treatment has to be individualistic, which ensures that mistakes in diagnosis or treatment are minimal. Nowadays modern aspects of diagnosis including investigations are also taken in to account before treating a patient.
Importance is given to the basic physiological constitution of the person based on the Siddha physiology. According to Siddha physiology, the basic body constitution of a person is classified in to different types like vatha udal (vatha body), pitha udal (Pitha body) & kaba udal (Kaba body).
Siddhars developed Naadi method (diagnosis using pulse reading) to sense the normality or disturbances in the interior of our body and to diagnose and confirm illnesses. The pulse movements (pulsations) felt is compared to the way of movement or locomotion of different animals to show the intensity felt in different body conditions for easy interpretation. Pulse reading can be done in 10 sites in the body out of which the one felt over radial artery is considered the best. It is felt in left hand for females and in right hand for males. It is usually felt using 3 fingers (index, middle and ring fingers) in view of assessing the states of vaatham, pitham and kabam simultaneously.
According to Siddha system, there are 4448 types of diseases and 64 types of medicines (32 types of internal medicines and 32 types of external medicines). Choice of drug is made from these rich collections of single and compound drugs depending upon the need of the patient.