In the development of diseases, asthenia of healthy qi and sthenia of pathogenic factors oppose each other and are also related to each other. Therefore, asthenia syndrome and sthenia syndrome may appear simultaneously or transform into each other and appear in sequence. At the critical stage of diseases, there may appear false sthenia and false asthenia manifestations
 
Mixture of asthenia and sthenia:
Asthenia of healthy qi and sthenia of pathogenic factors exist simultaneously at the same stage in a patient. This morbid condition is usually caused by pathogenic factors in a sthenia syndrome impairing healthy qi, or by invasion of new pathogenic factors in an asthenia syndrome with deficiency of healthy qi, or by accumulation of pathological substances in the body due to deficiency of healthy qi and dysfunction of viscera in an asthenia syndrome. Mixture of asthenia and sthenia may be a stage in the development of a disease or may appear as two syndromes at the same time in a patient in which one is asthenia and the other sthenia. This morbid condition may be further divided into asthenia syndrome complicated by sthenia, sthenia syndrome complicated by asthenia and equality of asthenia and sthenia according to the levels of asthenia and sthenia.

Sthenia syndrome complicated by asthenia:
This syndrome is marked by predominance of pathogenic factors complicated by asthenia of healthy qi. For example, in an internal sthenic heat syndrome with the manifestations of high fever, flushed complexion, dysphoria, sweating, reddish tongue and full and large pulse, there appear at the same time such symptoms like thirst, scanty brownish urine and retention of dry feces. Such a morbid condition is due to consumption of body fluid by predominant heat and exuberance of pathogenic heat.

Asthenia syndrome complicated by sthenia:
This syndrome is marked by deficiency of healthy qi complicated by retention of sthenic pathogenic factors. For example, at the advanced stage of seasonal febrile disease, there appear such symptoms like low fever, dispiritedness, dry mouth, poor appetite, furless tongue and thin pulse, etc. Such a morbid condition is typical of asthenia syndrome complicated by sthenia marked by deficiency of healthy qi due to impairment of qi and yin by remaining heat.
 
Equality of asthenia and sthenia:
This syndrome is marked by equal degree of the deficiency of healthy qi and sthenia of pathogenic factors. For example, tympanites due to failure of asthenic spleen and kidney yang to transform qi and transport fluid is marked by manifestations of sthenia syndrome like drum-like abdomen and scanty urine as well as by symptoms of asthenia syndrome like aversion to cold, cold limbs, pale complexion, aching weakness of loins and knees and deep-thin pulse, etc. In such a morbid condition, the degree of the deficiency of healthy qi and the degree of the sthenia of pathogenic factors are practically equal.