Sputum is a kind of sticky fluid, substance produced by disturbance of fluid metabolism, excreted from the lung and trachea due to dysfunction of the lung and the spleen. That is why it is said that "the spleen is the source of sputum, while the lung is the container of sputum". The production of sputum may bring about various diseases. So it is said that "sputum is produced by diseases, but sputum further worsens diseases".

Yellowish and sticky, or hard and coagulated sputum is heat-sputum produced by exogenous wind-heat, or by accumulation of endogenous heat which fumigates the lung. Whitish, thin or blackish sputum is cold-sputum due to consumption of yangqi by cold, failure of qi to transform fluid and accumulation of dampness. Thin and frothy sputum is wind-sputum due to pathogenic wind attacking the lung. Whitish, slippery and easily expectorated sputum is damp-sputum due to asthenia of the spleen and exuberance of dampness.

Scanty, sticky sputum difficult to expectorate, or with unproductive cough, is dry sputum due to pathogenic dryness attacking lung and consuming fluid in exogenous disease, in diseases due to internal. Impairment, sputum results from consumption of pulmonary yin and asthenia-fire scorching the lung. If sputum is mingled with fresh blood, it means that the pulmonary collaterals are impaired due to invasion of dry-heat into the lung as well as asthenia of yin and exuberance of fire. If sputum appears like purulent blood or chyle with foul smell, it is usually seen in pulmonary abscess due to accumulation of heat toxin in the lung and suppuration of the decayed resulting from blood stasis.

Inspection of spittle and saliva:     
Spittle refers to thick secretion in the mouth, while saliva refers to the thin part of secretion in the mouth. Spittle is related to the kidney and also to the spleen and stomach; while saliva is related to the spleen.

Reduced spittle and dry mouth and throat are usually caused by exhaustion of body fluid or failure of body fluid to flow upwards, often seen in consumption of body fluid in exogenous disease, or internal impairment and prolonged disease marked by asthenia of spleen qi, failure of qi to transform fluid or insufficiency of kidney yin. Frequent salivation from the corners of the mouth in infant is usually due to failure of the asthenic spleen to control fluid or due to attack of wind-heat. Distorted mouth with inability to close the mouth and spontaneous drooling in adult is usually seen in wind stroke. Frequent regurgitation of clear and thin fluid in the mouth is often caused by asthenic cold in the middle energizer; or insufficiency of kidney yang and disorder of qi transformation; or by internal exuberance of cold dampness and upward flow of pathogenic dampness.

Inspection of snivel:
Snivel refers to sticky fluid discharged from the nose. Snivel is related to the lung. Inspection of snivel is helpful for understanding the conditions of pulmonary qi and the nature of the pathogenic factors.
   
Stuffy nose with clear snivel indicates exogenous wind-cold:
Turbid and yellowish snivel indicates exogenous wind-heat or wind-cold transforming into heat. Persistent discharge of turbid yellowish pus-like snivel with foul smell indicates nasosinusitis due to accumulation and retention of damp-heat. Snivel mingled with blood is usually caused by dry-heat impairing collaterals; frequent discharge of snivel with bloody streaks probably indicates malignant syndrome of nasal cavity and further examination is necessary.