Siddha system of medicine has its own unique method of diagnosis to identify diseases and their causes. Examination of eight specific items are required, which is commonly known as Envagai Thervukal. These are –
Na (Tongue)- Black in Vatha, Yellow or red in Pitha, white in kapha
Niram (Colour) – Dark in Vatha, Yellow or red in Pitha, pale in Kapha
Mozhi (Voice) – Normal in Vatha, High pitched in Pitha, low pitched in Kapha
Kan (Eyes) – Muddy conjunctiva, yellow or red in Pitha, pale in Kapha
Sparisam (touch) – Dry in Vatha, Warm in Pitha, Chill in Kapha
Mala(Stool)- Black stools indicate Vatha, yellow indicates Pitha, Pale in Kapha
Neer (urine) – Early morning urine is examined. Straw colour indicates indigestion, reddish yellow indicates excessive heat, saffron colour indicates jaundice.
Nadi (pulse) – Pulse can be felt in the blood vessel one inch below the thumb of the patient, by softly pressing the index, middle and ring finger over it. Experienced physicians can read the degree of distortion of Vatha, Pittha and Kapha pulses.