The Fei 
–Shen 
relationship is mainly reflected in Qi movement, water metabolism, and the mutual supplementation of Yin-fluid.
Fei regulates water circulation, and Shen regulates water metabolism. Fei regulates respiration, and Shen regulates the reception of air energy. Shen and Fei can contribute to the condition of “the Shen failing to accept the fresh Qi” 
, which manifests as breathlessness, cough, or asthma. Fei and Shen cooperate to metabolize water.
Clinically, deficient Fei -Yin and deficient Shen -Yin often occur simultaneously, with symptoms that include a dry throat at night, a dry cough, night sweats, a feverish sensation of the palms and soles, and so on.