Rakta dhatu (blood tissue)

Blood is counted along with the doshas and called a dosha; because it is vitiated by vāta and the other vitiators, the same blood is also called a tissue (dhātu).

Blood vitiated by vata is described as very dark, frothy, thin and quick to flow; blood vitiated by pitta as blue, very yellow or black, foul-smelling and avoided by insects, mosquitoes and flies.

Blood vitiated by kapha is described as thick, slimy, flesh-like, slow to flow, cold and coloured like red-ochre water, while natural blood is red like indragopa, neither too thick nor too thin and not discoloured.

When vitiated blood is properly removed by a physician who knows the method of venesection, disease is said to subside and health, lightness of body, peace of mind and firmness of self and senses follow.

The sages are said to call pure blood the very life of the body; it is the root and constant support of the body's existence and gives bright complexion and nourishment, so the physician should always protect it.