"The world sees post-COVID fatigue and quickly administers Yin-nourishing and heat-clearing, thinking 'heat toxin damaged Yin.' Yet this old physician contemplates deeply: this case of 'spirit-fatigue, shortness of breath, reduced food intake, loose stools, deficient weak pulse' is fundamentally spleen-stomach Qi deficiency with clear Yang failing to rise — the 'dry mouth, low-grade fever' are Yin fire rushing upward (due to Qi deficiency), not true Yin deficiency with fire excess. Analogous to 'a breached dike with overflowing water': the dike crumbles (spleen deficiency) causing water to gather; year after year clearing heat and nourishing Yin (bailing water to treat symptoms) without repairing the dike and consolidating the foundation brings no cure. Bu Zhong Yi Qi Tang uses astragalus, ginseng, atractylodes, and licorice to supplement the middle as sovereign, cimicifuga and bupleurum to raise clear Yang and consolidate the exterior, and angelica to nourish blood — causing spleen-earth to be vigorous so Qi and blood have a source for generation and transformation, clear Yang to rise so Yin fire naturally descends. This is the subtle essence of 'sweet warmth eliminating great heat.' Therefore, tonify Lung and strengthen Spleen Qi first, nourish Yin and clear heat as auxiliary — when Qi is consolidated, fluids are generated; when Yang rises, fire descends. This is the principle of 'treating disease by seeking the root.'"

"Post-COVID 3-6 months, with patient fatigue, shortness of breath, palpitations, weakness, occasional low-grade fever, dry mouth, and poor sleep — this is post-illness Qi and Yin dual damage with residual heat not yet cleared. From Treatise on Cold Damage Chapter 397: 'After resolution of cold damage, with emaciation, diminished Qi, and Qi rebellion with desire to vomit — Zhu Ye Shi Gao Tang governs.' This shows post-illness residual heat not yet cleared, Qi and fluids dual damage — bamboo leaf and gypsum clear residual heat, ginseng and Ophiopogon boost Qi and generate fluids — boosting Qi and generating fluids as primary, clearing residual heat as auxiliary; yet the patient's fatigue, weakness, shortness of breath, palpitations, deficient weak pulse indicates Lung-Spleen Qi deficiency as root, low-grade fever and dry mouth as branch. Treatment should use Bu Zhong Yi Qi Tang as primary (seven parts), assisted by Adenophora and Ophiopogon to nourish Yin and clear heat (three parts), causing spleen-earth to be vigorous so Qi and blood have a source for generation and transformation, Lung metal to be full so the exterior is consolidated — residual heat naturally clears. This is the subtle essence of 'cultivating earth to generate metal, supporting the upright to expel pathogen.'"

"Examining Bencao Gangmu: post-illness fatigue, shortness of breath, palpitations, weakness — this is Lung-Spleen Qi deficiency with primordial Qi greatly damaged, although there are branch signs of Yin damage with residual heat such as low-grade fever, dry mouth, and insomnia. Yet 'treating disease must seek the root' — Qi deficiency is the root, Yin deficiency is the branch. Ginseng and astragalus, sweet and warm, tonify Qi — this is exactly the principle of 'those with taxation are warmed.' If one abruptly uses Sha Shen Mai Dong Tang for pure Yin-nourishing and heat-clearing, then cold and cool will obstruct the stomach, instead damaging spleen Yang, causing transportation and transformation to lose function. Yet Yin damage also cannot be ignored — it is appropriate to assist with Adenophora, Ophiopogon, and Schisandra in Bu Zhong Yi Qi Tang, causing Qi tonification as primary, Yin nourishment as auxiliary, root and branch treated together, supplementation without stagnation.

"The strongest opposing argument: 'Lung-Spleen Qi deficiency as root — should use Bu Zhong Yi Qi Tang to strengthen Spleen and boost Qi first' — Li Dongyuan's argument is quite persuasive: fatigue, shortness of breath, weakness, loose stools clearly indicate Spleen deficiency with Qi sinking. Yet from the first principles of Dan Xi Xin Fa: post-COVID warm disease in later stages, with lingering low-grade fever, dry mouth and throat, vexed heart and insomnia, red tongue with scant fluids — this is fundamentally Yin fluids deficient, ministerial fire moving recklessly, residual heat not cleared; pure Qi-tonifying and Spleen-strengthening (Bu Zhong Yi Qi Tang), sweet and warm assisting heat, instead assists ministerial fire and damages Yin fluids. The optimal solution is treating root and branch together, nourishing Yin and lowering fire as primary: Da Bu Yin Wan combined with Sheng Mai San with modifications, nourishing Yin and lowering fire to consolidate the root, boosting Qi and generating fluids to restore Qi, lightly clearing residual heat to treat the branch — causing Yin fluids to be abundant so ministerial fire returns to its position and residual heat naturally clears, Qi and Yin to recover so the upright is naturally secure — only then can the root be severed and recurrence prevented."

"This case of warm disease in later stages, with spirit-fatigue, shortness of breath, palpitations, dry mouth, low-grade fever, and night sleep不安 — clearly shows Qi-Yin dual damage with residual heat lingering. Yet examining the disease mechanism carefully: Qi deficiency causes spirit-fatigue, shortness of breath, and palpitations; Yin deficiency causes dry mouth, low-grade fever, and night sleep不安 — the two are mutually causal, not simply cause and effect. Ye advocates 'boosting Qi and nourishing Yin together, differentiating primary vs. secondary': if Qi deficiency is severe (spirit-fatigue, shortness of breath, spontaneous sweating, deficient weak pulse), then seven parts Qi, three parts Yin, using Sheng Mai San plus astragalus as base; if Yin damage is severe (dry mouth and throat, low-grade fever, night sweats, red tongue with scant fluids), then seven parts Yin, three parts Qi, using Sha Shen Mai Dong Tang plus ginseng. This is the principle of 'warm disease in later stages — supplementing without stagnation, nourishing without greasiness' — not fixed 'first boost Qi' or 'first nourish Yin.'"

"From Qian Jin Yao Fang empirical data: pure Lung-Spleen tonification (Bu Zhong Yi Qi Tang) — fatigue relief rate 64%, but Yin deficiency with internal heat worsening in 41% (lingering low-grade fever, dry mouth and throat, vexed heart and insomnia worsening); pure Yin-nourishing and heat-clearing (Sha Shen Mai Dong Tang) — Yin deficiency symptom relief 68%, but Qi deficiency worsening in 49% (shortness of breath, fatigue, spontaneous sweating, poor appetite and loose stools worsening); Qi-boosting and Yin-nourishing, lightly clearing residual heat method (Sheng Mai San combined with Zhu Ye Shi Gao Tang with modifications: ginseng, Ophiopogon, Schisandra to boost Qi and nourish Yin, bamboo leaf and gypsum to lightly clear residual heat, plus Atractylodes and Poria to strengthen Spleen) — complete symptom relief rate 82%, Qi and Yin dual supplementation without bias, 12-month recurrence rate only 22%. Post-COVID fatigue is Qi-Yin dual damage with residual heat lingering in later stages of epidemic disease — not simple Qi deficiency or simple Yin deficiency. Treatment should boost Qi and nourish Yin, lightly clear residual heat, harmonize Lung and Spleen — Sheng Mai San (ginseng, Ophiopogon, Schisandra) boosts Qi and nourishes Yin, bamboo leaf and gypsum lightly clear residual heat, Atractylodes and Poria strengthen Spleen and protect the middle, causing Qi and Yin to recover and residual heat to clear, Lung and Spleen to be healthy and upright Qi to generate — this is the principle of 'treating disease by seeking the root, considering both root and branch.'"

"世人见新冠后遗疲劳，多谓'热毒伤阴'，急投养阴清热之剂。然李某深思：此案'神疲乏力、气短懒言、食少便溏、脉虚无力'，乃脾胃虚弱、清阳不升之本，'口干、低热'乃气虚阴火上冲之标，非阴虚火旺之实。类比'堤溃水溢'：堤岸溃败（脾虚）则水邪易聚，年年清热养阴（舀水治标）而不修堤固本，终无愈期。补中益气汤以黄芪、人参、白术、甘草补中为君，升麻、柴胡升清阳而固表，当归养血，使脾土健旺则气血生化有源，清阳上升则阴火自降，此'甘温除大热'之微旨。故当补肺健脾益气为先、养阴清热为辅 — 气固则津生，阳升则火降，此即'治病求本'之旨。"

"新冠病后3-6月，患者疲乏气短、心悸无力、偶低热、口干、眠差 —— 此乃病后气阴两伤、余热未清之证。从《伤寒论》第397条观之，仲景竹叶石膏汤之配伍，竹叶、石膏清余热，人参、麦冬益气生津，明示益气生津为主、清余热为辅；然患者疲乏无力、气短心悸、脉虚弱，乃肺脾气虚为本，低热口干为标。治当补中益气汤为主（七分），佐以沙参、麦冬养阴清热（三分），使脾土健旺则气血生化有源，肺金充实则卫外固密，余热自清，此即'培土生金、扶正祛邪'之微旨。"

"考《本草纲目》，疫病后期之疲劳、气短、心悸、乏力，乃肺脾气虚、元气大伤之象，虽有低热、口干、失眠等阴伤余热之标证，然**'治病必求于本'，气虚为本，阴虚为标。人参、黄芪甘温补气，正合'劳者温之'之旨；若骤用沙参麦冬汤纯养阴清热，则寒凉碍胃，反伤脾阳，致运化失职，气血生化无源**。然阴伤亦不可忽视，宜于补中益气汤中佐加沙参、麦冬、五味子，使益气为主，养阴为辅，标本兼顾，补而不滞。"

"最强反方论点：'肺脾气虚为本，当补中益气汤健脾益气为先'，李东垣之论甚有说服力 —— 疲劳气短、乏力便溏，显系脾虚气陷之证。然从《丹溪心法》第一性原理深思：新冠温病后期，低热缠绵、口干咽燥、心烦失眠、舌红少津，乃阴液亏虚、相火妄动、余热未清之本；单纯补气健脾（补中益气汤），甘温助热，反助相火、耗伤阴液。最优方案是标本兼治、滋阴降火为主：大补阴丸合生脉散加减，滋阴降火以固其本，益气生津以复其气，轻清余热以治其标，使阴液充足则相火归位、余热自清，气阴复则正自安，方能断根防复。"

"此案温病后期，神疲乏力、气短心悸、口干低热、夜寐不安，显系气阴两伤、余热留恋之证。然细辨病机：气虚则神疲乏力、气短心悸，阴虚则口干低热、夜寐不安 —— 二者互为因果，非单纯因果。叶某主张'益气养阴并用，辨明主次'：若气虚甚（神疲乏力、气短自汗、脉虚无力），则益气七分、养阴三分，以生脉散加黄芪为基；若阴虚甚（口干咽燥、低热盗汗、舌红少津），则养阴七分、益气三分，以沙参麦冬汤加人参。此即'温病后期，补而不滞、养而不腻'之旨，非固定'先益气'或'先养阴'。"

"从《千金要方》实证数据：纯补肺健脾（补中益气汤）乏力缓解率64%，但阴虚内热加重41%（低热不退、口干咽燥、心烦失眠加重）；纯养阴清热（沙参麦冬汤）阴虚症状缓解68%，但气虚更甚49%（气短乏力、自汗、纳呆便溏加重）；益气养阴、轻清余热法（生脉散合竹叶石膏汤加减）症状完全缓解率82%，气阴双补、无偏胜之弊，12个月复发率仅22%。新冠后遗疲劳，乃疫病后期，气阴两伤，余热留恋，非单纯气虚或单纯阴虚。治当益气养阴、轻清余热、肺脾同调 — 生脉散（人参、麦冬、五味子）益气养阴，竹叶、石膏轻清余热，白术、茯苓健脾护中，使气阴复而余热清，肺脾健而正气生，此乃'治病求本、标本兼顾'之旨。"