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"Shanghan Lun" (Treatise on Cold Damage), authored by Zhang Ji of the Later Han Dynasty, aims to elucidate the profound principles of the "Huangdi Neijing" (Yellow Emperor's Inner Canon). The book does not quote a single line from ancient classics; all content is derived from the author's original insight. Its theories are comprehensive, and its treatment methods are complete. Generally speaking, ancient medical classics contained only treatment methods without specific prescriptions; this book marked the beginning of having both methods and formulas. It established the standard for future generations and is indeed a sacred text in the field of medicine! However, due to the passage of time, the text has become fragmented, containing many errors resulting from compilation and transcription. Now, by extensively collecting commentaries from various schools, selecting their essence, correcting errors, deleting杂content, supplementing omissions, and uncovering hidden meanings, it can be disseminated throughout the world, thereby making the great laws and subtle words even more evident to posterity!

The Taiyang (Greater Yang) channel governs the exterior and serves as the outer barrier of the body, commanding the Six Channels and integrating Ying (Nutrient) and Wei (Defensive) Qi. Whenever external pathogens invade the human body, they must first attack the exterior. If the exterior Qi is strong, then Wei Qi is solid and Ying Qi is guarded, so how can pathogens enter? The classic states: "Even if there is severe wind or toxic pathogen, it cannot harm him." This refers to such a situation. If the exterior Qi is deficient, then Ying and Wei Qi cannot resist external pathogens, so pathogens take advantage of the deficiency. The classic states: "Deficient pathogens cannot injure humans alone; they must wait for the body's deficiency before invading." Wei belongs to Yang; Ying belongs to Yin. Wind belongs to Yang pathogen; Cold belongs to Yin pathogen. Pathogens injure the body according to their affinity, so when struck by Wind, Wei Qi is affected; when injured by Cold, Ying Qi is affected. When Wei division is affected by pathogens, sweating occurs, which is considered Deficient Evil, corresponding to Guizhi Tang (Cinnamon Twig Decoction) syndrome. When Ying division is affected by pathogens, no sweating occurs, which is considered Excess Evil, corresponding to Mahuang Tang (Ephedra Decoction) syndrome. When both Ying and Wei divisions are affected, neither sweats, both are Excess Evil, corresponding to Da Qinglong Tang (Major Blue Green Dragon Decoction) syndrome. These three major therapeutic principles, if applied correctly, will resolve the pathogens immediately; if applied incorrectly, hundreds of complications may arise. Since Wind is the leader of hundred diseases, Wind striking Wei is listed in the Upper Section, while Cold injuring Ying and Wind-Cold injuring both are listed in the Middle and Lower Sections. The details of these categories are explained below this section, allowing readers to understand clearly upon opening the book and have something to follow.

Taiyang disease manifests with a floating pulse, stiffness and pain in the head and neck, and aversion to cold.
[Note] Taiyang refers to the Bladder Channel. Taiyang disease refers to the pathology occurring in the Taiyang Bladder Channel. Taiyang governs the exterior, and the exterior integrates Ying and Wei. Wind pathogen invades Wei, Cold pathogen injures Ying; both are exterior pathologies. A floating pulse is the pulse of exterior disease. Stiffness, pain in the head and neck, and aversion to cold are symptoms of exterior disease. The Taiyang meridian ascends to the forehead, intersects at the vertex, enters to connect with the brain, emerges again to descend separately through the neck, connecting to Fengfu (GV16); thus, when pathogens lodge in the meridian, they inevitably cause stiffness and pain in the head and neck. Aversion to cold occurs because of injury by Wind and Cold, hence the aversion. This clause is presented first as the outline for Taiyang disease. Whenever Taiyang disease is mentioned in the Upper, Middle, and Lower sections, it refers to this pulse and symptom complex.
[Commentary] Ying and Wei are both generated from the postnatal grain qi of the Stomach. The clear part becomes Ying, and the turbid part becomes Wei. Wei is the vigorous and rapid aspect of Qi; Ying is the refined essence within Blood. From the perspective of their fixed forms, they are called Qi and Blood; from the perspective of their flowing functions, they are called Ying and Wei. Ying flows within the vessels, so it belongs to Yin; Wei flows outside the vessels, so it belongs to Yang. However, the reason Ying and Wei flow is rooted in the primordial Qi of the Kidneys, so they are also referred to as Qi, namely Ying Qi and Wei Qi.
[Collected Notes] Hua Shou said: The pulse appearing above the flesh indicates an exterior condition.
Fang Youzhi said: The exterior refers to the skin, where Ying and Wei reside. Therefore, if the pulse is floating in all positions (Cun, Guan, Chi), it indicates that the disease is in the Taiyang exterior. "Neck" refers to the back of the neck. Aversion to cold includes aversion to wind. When Wind and Cold initially invade and stagnate in the exterior, they cannot overcome the external confrontation of Wind and Cold, hence the fear and aversion.
Cheng Yingmao said: Among the manifestations of the Taiyang channel, headache and aversion to cold are the most accurate, so it is presented first.
Wu Renju said: The head is the common position of the Three Yang channels, and the neck is the exclusive position of the Taiyang channel. If there is obstruction, preventing it from being soft and flexible as usual, it is called stiffness and pain.

Taiyang disease manifesting fever, sweating, aversion to wind, and a moderate pulse is named Wind Strike (Zhongfeng).
[Note] Taiyang disease refers to the pulse floating, stiffness and pain in the head and neck, and aversion to cold mentioned in the first clause. Wei is Exterior Yang, and Wind is a Yang pathogen. When Wind pathogen invades humans, Wei Qi is affected, following the principle of similarity. Wind striking Wei causes fever. Since both Wind and Wei are Yang, their nature is inherently hot, so heat develops rapidly, unlike Cold Injury which waits for closure and stagnation before generating heat. Wei disease fails to secure the exterior and is steamed by Yang pathogen, so pores open and sweat is produced. Sweating leads to exterior deficiency, and being disturbed by Wind causes aversion to wind. Wind has a soft nature, so the pulse is moderate. This follows the previous clause to describe Taiyang disease accompanied by these pulses and symptoms, named Wind Strike, serving as the outline for Wind Strike disease. Henceforth, whenever Wind Strike is mentioned, it refers to this pulse and symptom complex.
[Collected Notes] Fang Youzhi said: A moderate pulse refers to "Yang floating and Yin weak" mentioned later. It means that since there is the Taiyang disease outlined in the first clause, plus fever, sweating, aversion to wind, and a moderate pulse, the disease is caused by touching Wind, hence named Wind Strike.
Wang Hu said: Wind Strike does not refer to the Zhong Fu (Middle Viscera), Zhong Zang (Middle Organs), or Zhong Xue Mai (Middle Collaterals) described by Li Dongyuan. Essentially, the character "Zhong" (Strike/Hit) has the same meaning as "Shang" (Injure). In Zhang Zhongjing's treatise, he does not directly say Shang Feng (Wind Injury) lest later scholars fail to observe carefully and confuse cough, nasal congestion, and heavy voice associated with common Wind Injury. Thus, he uses "Zhong" to distinguish it. The moderate pulse should be read as Floating-Moderate. Floating is the pulse of Taiyang disease, and Moderate is the pulse of Wind Strike. The Tight pulse in the Middle Section should also be understood similarly.

Taiyang Wind Strike, characterized by Yang floating and Yin weak, where Yang floating indicates spontaneous heat and Yin weak indicates spontaneous sweating, accompanied by shivering aversion to cold (Sese), chilly aversion to wind (Xixi), mild fever (Xixi), nasal congestion (Biming), and dry retching (Gan'ou), is primarily treated with Guizhi Tang (Cinnamon Twig Decoction).
[Note] Taiyang Wind Strike combines the previous two clauses and details the symptoms to provide treatment. Henceforth, whenever Taiyang Wind Strike is mentioned, it refers to this pulse and symptom. "Yin and Yang" here refer to Ying and Wei, not the floating/sinking of Cun/Guan/Chi positions. Yang floating refers to Yue Ren's description of "three bean floats, Lung float." The Lung governs skin and hair; obtaining this indicates the float of the Wei division. Six-bean float is the Heart float. The Heart governs blood vessels; obtaining this indicates the float of the Ying division. Compared to the Wei float, the Ying float is weaker and less forceful, hence "Yang floating and Yin weak." When Wei is occupied by Wind, Wei pathogen becomes strong causing fever. Hence, "Yang floating indicates spontaneous heat." When Ying is steamed by pathogens, Ying fails to secure causing sweating. Hence, "Yin weak indicates spontaneous sweating." Disharmony between Ying and Wei leads to loose and relaxed muscle surface, resulting in Sese aversion to cold, Xixi aversion to wind, and Xixi fever. However, the disease is in the skin and hair exterior, unlike Cold Injury's high fever and no sweat, where aversion to cold persists even near fire and aversion to wind persists even in a closed room. Skin and hair internally connect to the Lung. If skin and hair are insecure, Wind pathogen invades the Lung, causing Qi congestion and nasal congestion. The chest is the root of Yang Qi. If Wei Yang is interfered with by Wind pathogen and cannot distribute, Qi rebels upward causing dry retching. Therefore, Guizhi Tang (Cinnamon Twig Decoction) is suitable to release the muscle layer, secure the exterior, and harmonize Ying and Wei.
[Collected Notes] Cheng Yingmao said: Sese aversion to cold describes the muscles contracting due to cold invasion. Xixi aversion to wind describes the muscles trembling due to wind, unable to resist due to looseness. Xixi fever describes the muscles steaming with heat, gathering and wanting to rise. These terms describe sensations from the skin and hair, distinguishing them from Cold Injury symptoms by depth and superficiality.

Guizhi Tang (Cinnamon Twig Decoction) Formula
Guizhi (Cinnamon Twig) (3 liang), Shaoyao (Peony Root) (3 liang), Gancao (Licorice Root, honey-fried) (2 liang), Shengjiang (Fresh Ginger, sliced) (3 liang), Dazao (Jujube, broken open) (12 pieces).
Crush the five herbs. Use 7 sheng of water, simmer gently to obtain 3 sheng, remove dregs. Take 1 sheng at a temperature suitable for drinking. Shortly after taking, drink over 1 sheng of hot thin porridge to assist the medicinal power. Cover warmly for about one hour until the whole body has a slight perspiration, which is ideal. Do not let sweat flow profusely, otherwise the disease will not be cured. If sweating after the first dose cures the disease, stop subsequent doses; do not finish the remaining decoction. If no sweating, administer again according to the previous method. If still no sweating, shorten the interval slightly, finishing three doses within half a day. For severe cases, observe continuously for one day and night. If symptoms persist after finishing one dose, prepare another. If no sweating occurs, administer up to two or three doses. Avoid raw/cold, sticky/slippery, meat, wheat products, five pungent spices, dairy/wine, and foul-smelling foods.
[Commentary] In the Guizhi Tang formula, there are two characters "remove peel" under Guizhi. Guizhi has a pungent and sweet flavor, and its efficacy lies entirely in the peel. If the peel is removed, it becomes dead wood, how could it have the effect of releasing the muscle layer and inducing sweat? These two characters should be deleted. Follow this example subsequently.
[Formula Analysis] Named Guizhi Tang (Cinnamon Twig Decoction) because Guizhi (Cinnamon Twig) is the Sovereign herb. Guizhi (Cinnamon Twig) is pungent and warm; pungency disperses, warmth unblocks Wei Yang. Shaoyao (Peony Root) is sour and cold; sourness astringes, cold enters Ying Yin. Guizhi (Cinnamon Twig) as Sovereign paired with Shaoyao (Peony Root) implies astringing sweat within dispersing sweat; Shaoyao (Peony Root) as Minister assisting Guizhi (Cinnamon Twig) achieves adjusting Wei within harmonizing Ying. The pungency of Shengjiang (Fresh Ginger) assists Guizhi (Cinnamon Twig) to release the exterior; the sweetness of Dazao (Jujube) assists Shaoyao (Peony Root) to harmonize the interior. Gancao (Licorice Root) is sweet and neutral, possessing the ability to stabilize the interior and repel the exterior, used to harmonize Middle Qi, thereby harmonizing interior/exterior and all herbs. Relying on the mutual assistance of Gui/Shao, the harmony of Jiang/Zao, and the mediation of Gancao, Exterior/Yang and Interior/Yin, Qi/Wei and Blood/Ying proceed without contradiction, achieving harmony through the integration of rigid and soft. The essence lies in drinking thin porridge shortly after administration to boost medicinal power. Since grain Qi fills the interior, it not only facilitates sweat production but also prevents lingering pathogens and future invasion. The brilliance lies in covering warmly for an hour to induce slight sweating, teaching the method of mild diaphoresis, and warning against profuse sweating which fails to cure. This formula is the crown of Zhang Zhongjing's formulas, the primary formula for releasing the muscle layer, inducing sweat, and harmonizing Ying and Wei. It is indicated for Wind Strike or Cold Injury with floating-weak pulse, spontaneous sweating, and unresolved exterior. Other conditions need only present one or two symptoms, not necessarily all. Therefore, it is included in Mahuang Tang (Ephedra Decoction), Gegen Tang (Kudzu Decoction), and Da Qinglong Tang (Major Blue Green Dragon Decoction). If there is no sweating, it is a Mahuang Tang (Ephedra Decoction) syndrome. A floating-tight pulse is the pulse for Mahuang Tang (Ephedra Decoction); certainly, Guizhi Tang (Cinnamon Twig Decoction) should not be used. However, if initially no sweating occurred, Mahuang Tang (Ephedra Decoction) was used to induce sweat, and after sweating, restlessness returns with a floating-numerous pulse; or after purgation, the pulse remains floating with Qi rushing upward; or after purgation, diarrhea stops but body pain persists, the classics use this formula to resolve the exterior. Indeed, although the exterior is unresolved, pores are now loose, pathogens are no longer in the skin/hair but in the muscle. Moreover, after sweating and purging, fluids are damaged. Thus, although pulses and symptoms resemble Mahuang Tang (Ephedra Decoction) syndrome, the primary treatment belongs to Guizhi Tang (Cinnamon Twig Decoction). Crude practitioners wrongly claim Guizhi Tang (Cinnamon Twig Decoction) treats only Wind Strike and not Cold Injury, causing suspicion and non-use. They also claim it only acts on the muscle exterior and treats no other diseases. They do not know that doubling Shaoyao (Peony Root) and Shengjiang (Fresh Ginger) and adding Renshen (Ginseng Root) creates Guizhi Xinjia Tang (Cinnamon Twig Plus Decoction) to treat Ying-exterior deficiency-cold and limb pain; doubling Shaoyao (Peony Root) and adding Yitang (Maltose) creates Xiaojianzhong Tang (Minor Construct the Middle Decoction) to treat interior deficiency palpitations and abdominal urgency/pain; adding Huangqi (Astragalus Root) creates Huangqi Jianzhong Tang (Astragalus Construct the Middle Decoction) to treat deficiency damage, deficiency-heat, spontaneous sweating, and night sweats. Thus, we know Zhang Zhongjing's formulas can treat hundred diseases. Take at a suitable temperature, drink hot thin porridge to assist medicinal power, aiming to fill interior grain Qi to facilitate sweat. Cover warmly for an hour, slight sweating, avoid profuse sweating, meaning do not over-sweat. Obtaining sweat requires neither slowness nor haste, neither too much nor too little. Slowness allows pathogens to linger; haste leaves pathogens behind. Profuse sweating destroys Yang; insufficient sweating fails to cure. If sweating after the first dose cures, it means the disease is light, resolved after one sheng. Stop subsequent doses, do not finish the decoction, meaning do not take the second sheng to avoid excess. If no sweating, take again according to previous method, meaning if first dose didn't work, take second sheng. If still no sweating after subsequent dose, meaning disease unresolved, take third sheng. Shorten interval slightly, finish three doses in half a day, meaning accelerate slightly for the third sheng, not too slow, taking about three hours to finish three doses, fitting the appropriateness of dosing. For severe cases, if one dose (three sheng) doesn't resolve disease, take another dose. If still unresolved, take up to three doses, observing for twenty-four hours, insisting on sweat and resolution before stopping. Later mentions of "following Guizhi Tang (Cinnamon Twig Decoction) administration method" refer to this.

Taiyang disease manifesting fever and sweating is due to Ying weakness and Wei strength, hence sweating. To rescue from Wind pathogen, Guizhi Tang (Cinnamon Twig Decoction) is suitable.
[Note] This explains the meaning of Yang floating and Yin weak from the previous clause. The classic states: "Pathogen excess constitutes Excess, Essence depletion constitutes Deficiency." When Wei is invaded by Wind, fever occurs; pathogen becomes strong, hence Wei Strength, meaning strong pathogen in Wei. When Ying is steamed by pathogens, sweating occurs; essence becomes weak, hence Ying Weakness, meaning weak Yin in Ying. This causes fever and sweating. To rescue from Wind pathogen, Guizhi Tang (Cinnamon Twig Decoction) is suitable.
[Collected Notes] Fang Youzhi said: Previous clause said Yang floating and Yin weak; this says Ying weak and Wei strong. Wei strong is Yang floating, Ying weak is Yin weak; they speak mutually to illuminate each other. Rescue means relief and protection. Saying "pathogenic Wind" instead of "Wind pathogen" refers to the entity itself.

If a patient has no internal organ diseases but experiences periodic fever and spontaneous sweating without recovery, this is disharmony of Wei Qi. Inducing sweat before the onset will cure it; Guizhi Tang (Cinnamon Twig Decoction) is suitable.
[Note] This explains the symptom of Ying-Wei disharmony from the previous clause and clarifies treatment for periodic fever and sweating. "Zang" refers to the interior. "No other disease" means no other internal diseases. Periodic fever and sweating, with exterior disease lingering, indicates not Ying-Wei disharmony, but Wei strength failing to harmonize with Ying. One should preemptively use Guizhi Tang (Cinnamon Twig Decoction) to release the muscle layer and induce sweat before fever and sweating occur, intercepting and overcoming the pathogen to suppress its momentum, leading to heat reduction and sweat cessation, curing the disease.
[Collected Notes] Fang Youzhi said: "Periodic" refers to temporary occurrence. Wei Qi disharmony means exterior has pathogenic Wind causing disharmony. "Before onset" means before fever starts.
Cheng Zhi said: Various Yin-deficiency diseases also feature periodic fever and spontaneous sweating. If there are no internal diseases but periodic fever and sweating, it is Wei affected by Wind pathogen, unable to disperse. It is suitable to use Guizhi Tang (Cinnamon Twig Decoction) to strike when it is about to move.
Cheng Yingmao said: Guizhi is a muscle-releasing agent, yet sometimes described as inducing sweat. Why? Because it aids Wei Qi ascent, allowing righteous Qi to spread and sweat to emerge, differing from Mahuang Tang (Ephedra Decoction) which drives out pathogens causing sweat to leak externally.
Wang Hu said: Using Guizhi Tang (Cinnamon Twig Decoction) to induce sweat during fever and sweating cures it. If timing is missed, Wind pathogen enters the interior, disease heat deepens, and Guizhi Tang (Cinnamon Twig Decoction) is no longer suitable.

When a disease features constant spontaneous sweating, this is because Ying Qi is harmonious. Ying Qi harmony with external disharmony occurs because Wei Qi does not harmonize with Ying Qi. Since Ying flows within vessels and Wei flows outside, inducing sweat again will harmonize Ying and Wei, curing the disease; Guizhi Tang (Cinnamon Twig Decoction) is suitable.
[Note] This further explains the reason for Ying-Wei disharmony. Constant spontaneous sweating indicates Ying Qi is already harmonious. If Ying Qi is harmonious but heat persists, it means external Wei Qi is still disharmonious and does not co-harmonize with Ying Qi. Thus, although Ying Qi is harmonious, constant sweating continues, and disease persists. Since Ying flows within vessels and Wei flows outside, if Wei is disharmonious, disease persists despite Ying harmony. Therefore, inducing sweat again suppresses Wei and harmonizes Ying; once Ying and Wei are harmonized, the disease self-heals. Guizhi Tang (Cinnamon Twig Decoction) is also suitable.
[Collected Notes] Fang Youzhi said: This is similar to the previous clause. Previous used "periodic," this uses "constant," meaning always present. Previous mentioned Zang (Interior/Yin), this mentions Ying (Interior/Yin). "Periodic" makes the language concise; "constant" makes it detailed. They illuminate each other, sharing the same meaning.
Yu Chang said: This clarifies the principle of Wei affected by Wind pathogen causing Ying spontaneous sweating. Whenever sweating occurs with Ying harmony but heat persists, it is Wei strength failing to harmonize with Ying. Inducing sweat again expels Wind pathogen from muscle pores, reducing Wei strength and harmonizing with Ying. Just as drunken madness subsides when alcohol leaves the body. If Ying is affected by Cold pathogen and fails to harmonize with Wei, Mahuang Tang (Ephedra Decoction) is similarly appropriate.
Wu Renju said: The previous clause had periodic onset, this has no specific time. Lack of sweating but persistent heat also belongs to Ying-Wei disharmony. Harmony of Ying and Wei is true harmony, and Ying cannot harmonize alone.
Zhang Xiju said: Wei Qi thickens interstices, controls opening/closing, and defends the exterior. Now affected by Wind pathogen, it cannot defend the exterior, causing constant sweating and persistent heat. This is Ying Qi harmony but Wei Qi disharmony.
Wei Litong said: Previously using Guizhi to release muscle harmonized Wei, stopping periodic fever heat; here using Guizhi to induce sweat harmonizes Wei, stopping constant sweating. Releasing exterior resolves heat. Thus summarized: Ying-Wei harmony leads to recovery.

In Taiyang disease, if after initial administration of Guizhi Tang (Cinnamon Twig Decoction), vexation increases and symptoms remain unresolved, first puncture Fengchi (GB20) and Fengfu (GV16) acupoints, then administer Guizhi Tang (Cinnamon Twig Decoction) for recovery.
[Note] In Taiyang disease, if exterior symptoms remain unresolved after taking Guizhi Tang (Cinnamon Twig Decoction), it can be taken again. Now, initial administration not only fails to resolve but increases vexation, indicating excessive exterior pathogen. Hastily giving Guizhi might generate more vexation and heat. Therefore, puncture therapy should be performed first to disperse pathogenic heat in the meridian, then administer Guizhi Tang (Cinnamon Twig Decoction) to release Wind pathogen from muscle pores, harmonizing interior and exterior, naturally leading to sweating and resolution.
[Collected Notes] Fang Youzhi said: Guizhi's efficacy depends entirely on administration method; inducing sweat must follow the classic strictly. Improper administration leads to inadequate sweating and failure to cure, hence increased vexation. "Fan" (reverse/increase) means turning into heat and oppression. Fengchi (GB20) is located in the depression behind the ear, pressing induces sensation in the ear, intersection of Hand and Foot Shaoyang meridians; insertion depth is 4 fen (same-body cun). Fengfu (GV16) is located one cun above the hairline at the nape, within the depression of the large tendons, intersection of Du and Yangwei meridians; insertion depth is 4 fen (same-body cun).
Zhang Zhicong said: Although Fengchi (GB20) and Fengfu (GV16) are not Taiyang acupoints, they belong to the regions traversed by the Taiyang meridian, so puncturing them reduces the momentum of Taiyang disease.
Wei Litong said: This is highlighted to prevent misinterpreting this as transmitted irritability. Unresolved symptoms indicate all Taiyang signs are present; adding vexation indicates it is not interior transmission vexation but exterior unresolved vexation.

Spontaneous resolution must begin with vexation, followed by sweating and resolution. How do we know? A floating pulse indicates resolution through sweating.
[Note] Sweating fails to resolve and causes vexation, with Taiyang signs remaining, indicates excessive exterior pathogen; presence of Yangming signs indicates excessive interior heat. However, some cases feature pre-resolution vexation due to struggle between pathogen and righteous Qi, signaling impending sweat. During this vexation, resolution is uncertain, but if all six pulses are floating, it indicates pathogen returning to exterior, resolving through sweating.