Loss of yin and yang refers to a critical pathological state caused by sudden loss of great quantity of yin-fluid or yang-qi. Loss of yin or yang also pertains to relative predomination and relative decline of yin and yang, quite different from relative predomination and decline of yin or yang in the occurrence and severity of disease.

       

Loss of yang is usually caused by predomination of pathogenic factors and weakness of healthy qi to control pathogenic factors, frequent deficiency of yang and overstrain, wrong application of diaphoresis and profuse sweating that result in sudden loss of yang-qi, leading to the symptoms of profuse sweating, cold sensation in the skin, feet and hands, lying with the knees drawn up, spiritual lassitude and indistinct pulse, etc.

     

Loss of yin is usually caused by exuberant pathogenic heat, violent vomiting, profuse sweating and diarrhea that result in loss of great quantity of body fluid with the symptoms of emaciation, curled skin, sunken ocular orbit, scanty and sticky sweating, irascibility and very weak pulse, etc.

Though loss of yin and loss of yang may appear solitarily, the loss of one side often leads to immediate exhaustion of the other because yin and yang depend on each other to exist. Thus untimely treatment of loss of yin or loss of yang may lead to death because "separation of yin and yang exhausts essence."