Heat reaches the exterior and severely damages the Wei (Defensive) Qi, thus failing to resist wind-cold. This is distinct from the aversion to wind in Wind-Strike or the aversion to cold in Cold Damage; it merely indicates that deficiency of Wei Qi manifests as aversion to wind, while deficiency of Ying (Nutritive) Qi manifests as aversion to cold. Furthermore, Warm Disease (Wen Bing) and Heat Disease (Re Bing) may also initially present with Exterior Syndrome before transmitting to the Interior. This occurs because stagnant heat rises from the interior to the exterior, becoming trapped in the Cou Li (pores and interstices), unable to vent outward, and subsequently returning inward to form a syndrome amenable to purgation. This differs from Shang Han (Cold Damage), which originates at the exterior.

Some individuals fail to comprehend this principle and seek a Tight Pulse (Jin Mai) in cases of Warm or Heat diseases occurring in spring and summer, which is indeed negligent. It must be understood that a Tight Pulse is indicative of Cold; it appears only when Cold Pathogens are present and disappears when they are absent. If a Tight Pulse appears in Warm or Heat diseases, it is due to a secondary exposure to sudden, pathogenic cold, or excessive consumption of cold food causing internal injury—not its inherent nature.

Others, unfamiliar with pulse morphology, mistake a Wiry Pulse (Xian Mai) for a Tight Pulse, diagnose it as Cold, and treat recklessly. A pulse that is vigorous and forceful often accompanies a wiry quality; how can it be mistaken for a tight pulse and diagnosed as cold?

The pulses of Warm and Heat diseases typically manifest at the muscle level rather than being superficial, and the Right Hand pulse is often stronger than the Left Hand pulse, truly reflecting stagnant heat within. If the Left Hand pulse is strong or superficial, it indicates a secondary exposure to wind-cold; otherwise, it is not a Warm or Heat disease but an acute contraction of wind-cold. In Warm and Heat diseases, if there is no secondary exterior syndrome, although exterior signs may occasionally appear, interior syndromes predominate; thus, thirst is rarely absent. The treatment method should primarily focus on clearing interior heat, accompanied by resolving the exterior. There are also cases where treating the interior resolves the exterior spontaneously.

I frequently observe that when physicians treat Warm-Heat diseases, even if they mistakenly use purgation for the interior, serious harm is rarely caused. However, if they mistakenly use diaphoresis (sweating methods) for the exterior, the complications are incalculable. This sufficiently demonstrates that the heat originates from the interior and moves outward.

Cases where mistaken purgation leads to severe harm usually involve epidemic conditions contracted by sudden cold in spring and summer, where the pathogen remains purely in the exterior without entering the interior. These cannot be discussed together with Warm or Heat diseases.

Because the general public conflates Warm and Heat diseases with Shang Han, they cling to the character "Cold" to seek a Floating-Tight pulse and employ warming herbs. Such practices, confusing name with reality and harming life, necessitate the correction of terminology.

Moreover, medical texts often discuss "Four Seasons Shang Han," grouping spring/summer Warm-Heat diseases with autumn/winter Shang Han without distinction. Autumn/winter Shang Han constitutes True Shang Han, whereas spring/summer Shang Han refers to Cold Epidemics. These are fundamentally different from Warm and Heat diseases and should not be treated identically. Alas, this error has persisted for a long time.

Nevertheless, regarding the method of purging the interior, if the goal is indeed to remove heat with cold properties, there is no need to insist on differences. However, the method of releasing the exterior must absolutely differ. Furthermore, Shang Han directly injuring the Yin meridians, or Tai Yang syndrome failing to stagnate into heat and transmitting to Yin meridians to become a Cold syndrome requiring warming, is vastly different from Warm and Heat diseases; reckless treatment is impermissible.

Some who know one aspect but not the other claim that Zhang Zhongjing’s exterior-releasing formulas are now unusable, while interior-purging formulas are usable. Alas, what is the rationale for their usability or non-usability?

If one can distinguish the etiology, correct the nomenclature, examine the clinical presentation, and formulate appropriate treatments, are there still errors? For conditions caused by seasonal pathogenic qi or those altered by secondary exposure to different pathogens, one must consider the timing and specific pathogenic factors, referencing and modifying the methods of both Shang Han and Warm-Heat diseases. One must certainly not indiscriminately apply Zhang Zhongjing’s formulas for immediate-onset Shang Han to all such cases.