Six excesses pattern differentiation is the categorization of patterns according to pathological conditions attributable to six excesses, for making a diagnosis.

External wind pattern is caused by external wind pathogen alone or together with other pathogenic factors such as dampness, heat, or pestilential toxin. It is manifested by aversion to wind or to wind and cold, mild fever, sweating, thin white coating and floating pulse; or accompanied by stuffy nose, runny nose, and sneezing; or accompanied by itchy throat or sore throat and cough.

Occasionally, especially in children, wind causes itchy skin, and skin eruption*, such as rubella* and urticaria*. In some patients, the wind pathogen may cause numbness of the skin, deviated eye and mouth, or migratory* joint pains, or even edema of the head and face.

Wind opens interstices and sweat pores, suppresses* body yang qi from warming the body surface, resulting in sweating, aversion to wind or to wind and cold. The struggle between healthy qi and pathogenic wind raises the temperature regulating set-point in the brain, and generates more heat, resulting in mild fever. Thin white coating and floating moderate pulse are indicative of external wind or wind-cold contraction.

Cold pathogen usually attacks the exterior part of the body, but occasionally it attacks the viscera and bowels directly. Furthermore, exterior cold can transmit into the interior. Therefore, exogenous cold-caused patterns can be divided into exterior cold pattern and interior excess cold pattern.

Exterior cold pattern arises when wind-cold invades the exterior and suppresses body yang qi. This is characterized by pronounced* aversion to cold with mild fever, headache, generalized pain, absence of sweating, thin white tongue coating, and tight floating pulse, the same as the pattern of wind-cold fettering the exterior.

Interior excess cold pattern is attributable to external cold directly attacking the interior, or external cold attacking the exterior first and then entering the interior. It is manifested by intolerance of cold with cold limbs, somber white complexion, absence of thirst or liking for hot drinks, long voidings of clear urine, white moistened coating and slow sunken tight pulse.

The key point for differentiation of exterior and interior cold pattern is that exterior cold has fever but interior one usually does not. Exterior cold does not usually damage internal organs but interior cold always has the symptoms and signs of internal organ damage or qi or blood damage. Floating pulse indicates exterior pattern and sunken pulse suggests interior pattern.

Summer-heat pattern usually results from contraction of summer-heat and is marked by high fever with sweating, thirst, shortness of breath, lassitude*, cumbersome* limbs, short voidings of dark-colored urine, reddened tongue and rapid vacuous pulse*.

Heat increases body metabolism and steams body fluids, giving rise to high fever with sweating. When fluid is damaged and qi is consumed by summer-heat, the patient will be thirsty and will have short of breath, lassitude, and short voiding of dark-colored urine. Summer-heat attacking the body with dampness usually results in cumbersome limbs. Heat makes the tongue reddened and vacuous pulse is caused by deficiency of fluid and qi.

External dampness pattern results from contraction of external dampness. It is marked by heavy cumbersome limbs or accompanied by aching, heavy-head as if swathed*, eczema*, pruritus*, or aversion to cold and unsurfaced mild fever, slippery and slimy tongue coating, and soggy pulse.

Dampness impedes* movement and is heavy, when dampness invades the body, the patient has the sensation of heavy-head as if swathed, heavy body, and heavy cumbersome limbs. Dampness obstructs the meridians and this causes aching. Dampness is liable to* transform into heat and when dampness-heat steams the skin, pruritus or eczema occurs. Dampness is apt to* obstruct yang qi from reaching the surface of the body, resulting in aversion to cold; obstructed yang transforms into heat resulting in mild unsurfaced fever. Slippery and slimy tongue coating and soggy pulse are the signs of dampness.

Like external cold pathogen, external dryness pathogen does not only cause external dryness pattern, but also cause internal dryness pattern.

External dryness pattern arises when climatic dryness attacks the body and consumes the body fluid, commonly manifested by dry skin, dry nose, dry mouth and dry throat or dry cough. Dryness most frequently takes the mouth and nose as its pathways and attacks the defense qi and the lungs first; therefore, when dryness attacks the lung and damages body fluid, it usually gives rise to dry nose, dry mouth, dry throat and dry cough.*

External dryness not only attacks the exterior but also invades the interior and causes internal dryness pattern. This is manifested by emaciation, withered skin, dry throat, parched lips*, thirst, oliguria*, constipation, furless reddened tongue and rapid fine pulse.

Warm pathogen, heat pathogen and fire pathogen are in the same category, but in different severity. Logically heat is more severe than warm, and fire is more severe than heat. But clinically they are not really distinguishable*. Therefore, they are often named together, such as warm-heat disease and fire-heat pathogen.

Generally, warmth and heat are used to describe exterior patterns and fire is used to describe endogenous patterns, for example, wind-heat, summer-heat, heart fire, and liver fire.

Exterior heat pattern may arise when wind-heat invades the exterior. This is characterized by marked* fever with mild aversion to wind and cold, headache, sore throat, sweating and thirst, thin yellow tongue coating and rapid floating pulse.

Interior heat pattern can arise when external pathogen enters the interior, transforms into heat, and consumes the fluid. This is mainly manifested by fever with sweating, thirst with intake of fluid, vexation*, bitter taste in the mouth, short voiding of reddish urine, a reddened tongue with yellow coating, and rapid surging or rapid string-like pulse.