Internal toxin not only arises along with pathogenic Qi such as fire

phlegm

dampness and stasis

but also is an independent and objective pathogenic Qi itself. According to different sources

internal toxin can be divided into attached toxin and original toxin

while according to characteristics it can be devided into Yin toxin and Yang toxin. Just like other pathogenic Qi

it develops from basic substances under specific conditions and environment

so internal toxin is not only an etiology concept

but also an objective pathological product

evolving into a way of thinking about disease. Original toxin is the basis of emergency and severe diseases transforming into chronic disease in present disease spectrum of internal toxin. Its pathogenesis evolution has following principles: turbid turning into toxin

directing from inside to outside

as well as transmitting and changing along with the Qi

blood

vessels and collaterals. As a result

the lesions should be treated with Qi

blood

channel and collateral differentiation combined with Zang-Fu organ differentiation. Internal toxin accumulation and damage has gradually become the core pathogenesis of modern disease

so it is of vital academic and clinical importance to study further to define its scientific connotation and establish systematic internal toxin differentiation system.