Syndrome differentiation of cough first should distinguish exogenous cough from endogenous cough. Generally exogenous cough is characterized by sudden onset and short duration accompanied by exterior syndrome which is usually sthenic. Exogenous cough is usually divided into cough due to wind and cold and cough due to wind and heat. Cough due to wind and cold is marked by heavy cough and whitish thin sputum, accompanied by chills, thin nasal discharge, whitish thin tongue fur and floating and tense pulse which are the signs of attack by wind and cold on the exterior. Cough due to wind and heat is marked by unsmooth cough and yellowish thick sputum, accompanied by fever, aversion to wind, turbid nasal discharge, reddish tongue with yellowish thin fur and floating and rapid pulse which are the signs of wind and heat. Endogenous cough is characterized by slow onset and longer duration, accompanied by varied internal syndrome which often turns gradually from sthenia into asthenia.

Clinically it is divided into four syndromes, i. e. retention of phlegmatic heat in the lung, accumulation of phlegmatic dampness in the lung, consumption of pulmonary yin and asthenia of pulmonosplenic qi. The syndrome of retention of  phlegmatic heat in the lung is usually marked by cough with profuse, yellowish and sticky sputum, reddish tongue with yellowish fur and slippery and rapid pulse; the syndrome of accumulation of phlegmatic dampness in the lung is marked by cough with abundant whitish thin sputum, chest oppression, poor appetite, pale tongue with whitish greasy fur and soft and slippery pulse; the syndrome of   yin deficiency is marked by dry cough without sputum or   scanty and sticky sputum difficult to expectorate, accompanied by thirst, dry throat, reddish tongue with scanty  fur and thin and rapid pulse; the syndrome of asthenia of pulmonosplenic qi is marked by weak cough, whitish thin  sputum, shortness of breath, slouchiness to speak, weakness, polyhidrosis, pale tongue and thin and weak pulse.