Cold syndrome and heat syndrome, though different in nature, are correlated. They may simultaneously appear in one patient and manifest as mixture of cold and heat. Under certain conditions, they may transform into each other. During the development of diseases, especially at severe stage, there may appear such phenomena like false cold and false heat.
 
Mixture of cold and heat:
Cold syndrome and neat syndrome appear at the same time in one patient. It may be one stage at the development of a disease or signify two syndromes in one patient, i.e. a cold syndrome and a heat syndrome. The commonly encountered ones" are upper heat and lower cold, upper cold and lower heat, external cold and internal heat as well as external heat and internal cold.
 
Upper heat and lower cold syndrome:
For example, there are heat symptoms like feverish sensation in the chest, halitosis and swelling pain of gums in the upper part of the body accompanied by cold symptoms like abdominal pain and preference for warmth and loose stool in the lower part of the body.
 
Upper cold and lower heat syndrome:
For example, there are cold symptoms like cold stomachache, reduced appetite and vomiting clear drool in the upper part of the body accompanied by heat syndromes like scanty brownish urine, frequent micturition and painful urination in the lower energizer due to cold in the stomach and heat in the bladder.
 
External heat and internal cold syndrome:
This syndrome is usually caused by frequent existence of internal cold complicated by invasion of pathogenic heat; or by impairment of yangqi in the spleen and stomach in external heat syndrome due to excessive taking of cold drugs. For example, in patients with asthenia of spleen and kidney yang complicated by invasion of exogenous pathogenic heat, there appear borborygmus, abdominal pain and diarrhea with indigested food complicated by fever, slight aversion to wind and cold, headache and swelling sore throat, etc.
 
External cold and internal heat syndrome:
This syndrome may be caused in two ways. One is frequent existence of internal heat complicated by invasion of wind and cold. For example, manifestations of hyperactivity of liver fire like susceptibility to irritation, flushed complexion, red eyes, dizziness, distending headache, bitter taste and dryness in the mouth are complicated by external cold symptoms like aversion to cold, fever, anhidrosis and cough. The other is cold pathogenic factors transmitting into the internal and transforming into heat prior to the relief of external cold. For example, symptoms of external cold syndrome like severe aversion to cold and slight fever, pain of head and body, anhidrosis and floating pulse followed by internal transmission of pathogenic cold and continuous existence of external cold with the symptoms of internal heat syndrome like aggravation of fever, thirst, restlessness and reddish tongue.

In dealing with simultaneous appearance of cold syndrome and heat syndrome, trials should be made to distinguish the upper and the lower as well as the external and the internal. The differentiation of whether the cold is principal or secondary or whether heat is principal or secondary is also essential for establishing therapeutic principles and deciding treatment.