时疫本不当补，而有屡经汗、下、清解不退者，必待补而愈。此为病药所伤，当消息其所伤在阴、在阳，以施
补阴、补阳之法。疫邪为热证，伤阴者多，然亦有用药太过而伤阳者，则补阴、补阳又当酌其轻重，不可偏废。凡
屡经汗、下、清、和而烦热加甚者，当补阴以济阳。所谓
寒之不寒，责其无水者是，六味、四物、生脉、养荣诸方酌用。屡经汗、下、清、和，热退而昏倦痞利不止者，当
补阳。所谓养正以却邪者是，四君、异功、生脉、六君、理中、建中、附子等方酌用，诸证详后。
当补阴证∶舌干无苔，舌黑无苔，耳聋，目直视，目不明，服清凉药渴不止，服清凉药烦热加甚，服攻下药舌
苔愈长，服攻下药舌苔芒刺燥裂愈甚，服清凉药身热愈甚，身体枯瘦，用利水药小便愈不通，腰膝萎软，周身骨
节痛不可移动，多睡。
当补阳证∶多冷汗，汗出身冷经日不回，小便清而
多，大便利清谷，呕吐用清热开导药愈甚，自利用清下药愈甚，痞满。
外此，更有四损、四不足、三复证当补，详见后。
大劳、大欲、大病、久病后为四损。气血两虚，阴阳并竭，复受疫邪，正虚则邪入愈深，邪深则传化难出，汗、
下伤正而正脱，补助郁邪而邪锢，多不可治。然补泻兼施，间有愈者。有补泻合用之法，有先补后泻之法，有
先泻后补之法。凡人参败毒散、人参白虎汤、黄龙汤、竹叶石膏汤，皆补泻合用之法也。先用补剂，后施汗、下，
先补后泻之法也。先用汗、下，后施补剂，先泻后补之法也。当询病之来路，斟酌施治，尤当审现下之证。若纯见
实证，亦不可以疑似之见误人。大凡周身俱见大实、大热之证，而一、二处微见虚象，则吃紧照顾其虚；周身俱见
虚象，而一、二处独见实证，则吃紧斡旋其实。此治病之权衡也。若夫汗之而表证愈增，如头痛、身痛更甚之类；
清、下而里证愈增，如烦渴、痞满更甚之类，则大虚有盛候也，急宜补之毋疑。既辨其证，尤当细辨其脉。凡遇脉
之浮候盛大者，须谨察其沉候有无力处；六部脉皆盛者，须谨察其一部有独无力处。果得其一部一候之真无力，便
可略其诸部诸候之假有余，从而施治，有独见若神之妙。夫既询得其来路之大概，又察得其轻重之确凭，再加之脉
理精详，则烛照无遗矣。其损证之状甚多，当参后四不足条看。
Plague (epidemic pestilence) generally should not be treated with tonification. However, in cases where fever persists despite repeated applications of diaphoresis (sweating), purgation, and heat-clearing resolution, recovery may only be achieved through tonification. This occurs because the disease and improper medication have damaged the healthy qi (Zheng Qi). One must carefully assess whether the damage is to Yin or Yang, and apply methods to tonify Yin or Yang accordingly. Since plague pathogens belong to heat syndromes, Yin injury is more common; however, excessive use of cold or bitter drugs can also damage Yang. In such cases, the choice between tonifying Yin and tonifying Yang must be weighed according to severity, avoiding bias toward either approach.
For patients who experience aggravated irritability and fever after repeated treatments with diaphoresis, purgation, heat-clearing, and harmonizing methods, one should tonify Yin to support Yang. This corresponds to the principle: "When cold treatment fails to resolve cold symptoms, the fault lies in the lack of Yin fluid (Water)." Formulas such as Liuwei Dihuang Wan (Six-Ingredient Rehmannia Pill), Siwu Tang (Four-Substance Decoction), Shengmai San (Generate the Pulse Powder), and Yangrong Tang (Nourish the Nutritive Decoction) may be selected appropriately.
For patients whose fever subsides but who develop lethargy, mental cloudiness, epigastric fullness, and persistent diarrhea after repeated diaphoresis, purgation, heat-clearing, and harmonizing treatments, one should tonify Yang. This aligns with the principle: "Nourish the upright to expel the pathogenic factor." Formulas such as Sijunzi Tang (Four-Gentlemen Decoction), Yigong San (Yi-Gong Powder), Shengmai San (Generate the Pulse Powder), Liujunzi Tang (Six-Gentlemen Decoction), Lizhong Tang (Regulate the Middle Decoction), Xiaojianzhong Tang (Minor Construct the Middle Decoction), and Fuzi Lizhong Tang (Aconite Regulate the Middle Decoction) may be selected appropriately. Detailed descriptions of these syndromes follow later.
**Syndromes Requiring Yin Tonification:**
Dry tongue without coating; black tongue without coating; deafness; fixed gaze with inability to move eyes; blurred vision; thirst persisting despite cooling herbs; aggravation of irritability and fever after taking cooling herbs; thickening of tongue coating after using purgatives; worsening of prickly, dry, and cracked tongue coating after purgation; increased body heat after taking cooling herbs; emaciation and dryness of the body; obstruction of urination worsening after using diuretics; flaccidity and weakness of the lower back and knees; severe pain in bone joints preventing movement; excessive sleepiness.
**Syndromes Requiring Yang Tonification:**
Profuse spontaneous sweating of cold nature; body temperature remaining cold for a day after sweating; clear and frequent urination; loose stools containing undigested food (Wan Gu Bu Hua); vomiting worsening after using heat-clearing and guiding-out medications; diarrhea worsening after using clearing and purging medications; epigastric distension and fullness.
Beyond these, there are conditions known as "Four Damages" (Si Sun), "Four Deficiencies" (Si Bu Zu), and "Three Recurrences" (San Fu Zheng) that require tonification; see details later.
The "Four Damages" refer to states following extreme fatigue, sexual excess, severe acute illness, or prolonged chronic illness. These states involve deficiency of both Qi and Blood, and exhaustion of both Yin and Yang. If infected by plague pathogens while the healthy Qi is deficient, the pathogen penetrates deeper; deep-seated pathogens are difficult to eliminate. Diaphoresis and purgation may further damage healthy Qi leading to collapse, while blind tonification may cause stagnated pathogens to become entrenched. Such cases are often incurable. However, combining tonification and purgation occasionally yields cures. Methods include simultaneous tonification and purgation, tonification followed by purgation, and purgation followed by tonification. For instance, Renshen Baidu San (Ginseng Detoxifying Powder), Renshen Baihu Tang (Ginseng White Tiger Decoction), Huanglong Tang (Yellow Dragon Decoction), and Zhuye Shigao Tang (Bamboo Leaf and Gypsum Decoction) represent simultaneous tonification and purgation. Using tonics first, then applying diaphoresis or purgation, represents tonification followed by purgation. Applying diaphoresis or purgation first, then using tonics, represents purgation followed by tonification.
One must inquire into the history of the disease, deliberate on the treatment strategy, and especially examine current symptoms. If purely excess syndromes are present, do not let doubt lead to error. Generally, if the whole body exhibits signs of great excess and heat, but one or two areas show slight deficiency, priority must be given to addressing the deficiency. Conversely, if the whole body shows deficiency signs, but one or two areas distinctly show excess, priority must be given to managing the excess. This is the critical balance in treating diseases.
If diaphoresis causes superficial symptoms to worsen (e.g., increased headache and body pain); or if heat-clearing and purgation cause interior symptoms to worsen (e.g., increased irritability, thirst, and fullness), this indicates a state of great deficiency presenting with false excess signs. Urgent tonification is required without hesitation.
After distinguishing the syndrome, one must carefully differentiate the pulse. When the floating pulse appears large and vigorous, one must cautiously check if the deep pulse lacks strength. When all six pulse positions appear vigorous, one must carefully check if any single position lacks strength. If a true lack of strength is found in even one position or phase, one can disregard the false signs of excess in other positions and phases, thereby applying treatment with discernment akin to divine insight. Having gathered the general history, confirmed the severity, and analyzed the pulse principles in detail, one’s understanding will be comprehensive and unobstructed. The manifestations of damage syndromes are numerous; refer to the section on "Four Deficiencies" below for further details.