吞酸者，木气郁而不伸，痰饮因而阻塞，湿热郁积于肝而出，伏于肺胃之间，患
者必戒忿怒， 食菜蔬，以自养为妙，盖莫不由中官清气郁滞，败痰停饮宿食，酝造而
成也。所用之药，宜二陈加炒吴茱萸，顺其性而折之，此反佐之法，尤须以炒黄连为
君，苍术茯苓之类，皆不可缺。有因湿热在胃，饮食入胃，湿热郁遏，其食不得传化。
而为酸，如谷肉在器，则作酸也。故脾伤是其本，痰火是其标。亦有郁气伤脾者，实则
古方逍遥散，虚则归脾汤，加减服之。
凡中脘有饮，则嘈有宿垢则酸，然吐酸《素问》为热，东垣又言为寒，何也？盖吐
酸与吞酸不同，吐酸是吐出酸水，吞酸乃平时津液随上升之气，郁积而成，郁积之久，
湿中生热，故从木化，遂作酸味，非热而何？其有积之既久，不能自涌而出，伏于肺
胃之间，咯不得上，咽不得下，肌表得寒，则内热愈郁，而酸味刺心，肌表温暖，腠理
开发，或得香热汤丸，津液得行，亦得暂解，非寒而何？言热者，言其本，言寒者，
言其未也，凡病属热，有用寒药，独酸症，当兼热药以从治。喻嘉言曰∶甘温除热泻火
之法，施于作酸者，其酸转增，用必无功，故驱其酸，而返其甘，惟有用刚药一法，刚
药者，气味俱雄之药，能变胃而不受胃变者也。
嗳气者，即噫气也。胃中有郁火，膈上有稠痰，皆脾不运，浊气阻塞也。又云∶噫
气吞酸，此系食郁有热火，气冲上，宜黄芩为君，南星、半夏、陈皮为佐。
一方
吴茱萸（一两，去枝、梗，煎少时，浸半日，晒干） 苍术（米泔浸） 黄连（一两
，陈壁土炒，去土） 黄芩（一两，如上土炒） 陈皮（各一两） 或加桔粳一两，茯苓一
两，为末，神曲糊丸，绿豆大，每服二三十丸，时时津液下。
吞酸，是由于肝木之气郁结而不能舒展，导致痰饮随之阻塞，湿热郁积于肝脏而外发，潜伏在肺和胃之间。患病者必须戒除愤怒，食用蔬菜，以自我调养为妙，因为这种情况没有不是由中焦脾胃的清气郁滞，败坏的痰液、停聚的饮水和宿食，酝酿而成。所用的药物，适宜用二陈汤加入炒过的吴茱萸，顺应其本性而制约它，这是反佐的方法，尤其必须以炒黄连为君药，苍术、茯苓之类的药物，都不可缺漏。有因湿热在胃中，饮食进入胃后，被湿热郁遏，食物不能传导消化的情况。从而变成酸味，就像谷物和肉类放在容器中，就会变酸一样。所以脾脏受损是其根本，痰火是其表象。也有因郁气损伤脾气的，实证用古方逍遥散，虚证用归脾汤，加减服用。
凡是中脘部位有饮邪，嘈杂感就有宿垢则表现为吞酸。然而《素问》认为吐酸是热证，李东垣又说它是寒证，为什么呢？这是因为吐酸与吞酸不同，吐酸是吐出酸水，吞酸则是平时的津液随着上升的气机，郁结积聚而成，郁结积聚久了，湿气中生热，所以随木气变化，于是产生酸味，这不是热证是什么？那些积聚久了，不能自行涌出，潜伏在肺胃之间，咳不出来，咽不下去，肌表受寒，则内热更加郁结，酸味刺痛心脏；肌表温暖，腠理开泄，或者得到香热的汤剂丸药，津液得以运行，也能暂时缓解，这难道不是寒证吗？说它是热证，是说它的本质；说它是寒证，是说它的表象。凡是病属热证，有用寒凉药物治疗的，唯独酸症，应当兼用温热药物来顺从其病势（从治）。喻嘉言说：甘温除热泻火的方法，施用于作酸的病症，其酸味反而增加，使用必定无效，所以要驱除其酸味，恢复其甘味，只有使用刚药这一种方法。所谓刚药，就是气味都雄烈的药物，能够改变胃的状态而不被胃所改变的药物。
嗳气，就是噫气。胃中有郁火，膈上有稠痰，都是脾气不运化，浊气阻塞所致。又有人说：噫气和吞酸，这是由于食积有热火，气冲向上，适宜以黄芩为君药，南星、半夏、陈皮为佐药。
一方：吴茱萸（一两，去掉枝梗，煎煮片刻，浸泡半天，晒干），苍术（米泔水浸泡），黄连（一两，用陈壁土炒，去土），黄芩（一两，如上法用土炒），陈皮（各一两）。或者加桔梗一两，茯苓一两，研为细末，用神曲糊制成丸药，如绿豆大小，每次服用二三十丸，时时让津液送服。
Swallowing sour fluid (Tun Suan) occurs when the Wood Qi (Liver Qi) is stagnant and fails to extend, causing phlegm-fluids to block the pathway. Damp-heat accumulates in the Liver and manifests outward, lying latent between the Lungs and Stomach. Patients must abstain from anger and consume vegetables; self-nourishment is the best approach. This condition invariably arises from the stagnation of clear Qi in the Middle Jiao (Zhong Jiao), where spoiled phlegm, retained fluids, and undigested food ferment and combine. The appropriate medication should be Er Chen Tang (Two-Aged Decoction) with added stir-fried Evodiae Fructus (Wuzhuyu). This method follows the nature of the pathogen to subdue it, known as the counter-assistance method (Fan Zuo). Crucially, stir-fried Coptidis Rhizome (Huanglian) should be used as the sovereign drug, while drugs such as Atractylodis Macrocephalae Rhizoma (Cangzhu) and Poria (Fuling) are indispensable. In cases where damp-heat resides in the Stomach, food entering the stomach is constrained by this damp-heat and cannot be transformed and transported, thereby becoming sour, much like grain and meat turning sour when stored in a vessel. Thus, injury to the Spleen is the root cause, while phlegm-fire is the branch manifestation. There are also cases where stagnant Qi injures the Spleen; for excess patterns, use the ancient formula Xiaoyao San (Free and Easy Wanderer Powder); for deficiency patterns, use Guipi Tang (Restore the Spleen Decoction), taken with modifications.
Whenever there is fluid retention in the Zhongwan (CV12) area, rumbling sensations occur, and if there is accumulated filth, swallowing sour fluid results. However, *Su Wen* (The Classic of Difficult Issues) states that vomiting sour fluid is due to heat, while Li Dongyuan stated it is due to cold. Why? Because vomiting sour fluid differs from swallowing sour fluid. Vomiting sour fluid involves expelling sour water, whereas swallowing sour fluid is formed when normal body fluids rise with ascending Qi, stagnating and accumulating over time. Long-term accumulation generates heat within dampness, transforming according to Wood characteristics, thus producing a sour taste—is this not heat? When accumulation persists for a long time and cannot surge out spontaneously, it lies latent between the Lungs and Stomach, unable to be coughed up or swallowed down. When the exterior skin and muscles are exposed to cold, internal heat becomes more constrained, and the sour taste pierces the heart; when the exterior is warm, pores open, or aromatic hot decoctions/pills are taken allowing body fluids to circulate, temporary relief may occur—is this not cold? To say it is heat refers to its root; to say it is cold refers to its branch. Generally, for diseases classified as heat, cold medicines are used; however, for sour conditions, hot medicines must be combined to follow the disease's nature (Cong Zhi). Yu Jiayan stated: "The methods of sweet-warm to dispel heat and purge fire, when applied to sour conditions, will only increase the sourness and prove ineffective. Therefore, to drive away the sourness and restore sweetness, only the method of using 'Gang Yao' (Rigid/Strong Drugs) works. Gang Yao refers to drugs with potent aromas and flavors that can transform the Stomach without being transformed by it."
Belching (Ai Qi) is the same as Yi Qi. It is caused by stagnant fire in the Stomach and thick phlegm above the Diaphragm, resulting from the Spleen's failure to transport and turbid Qi blocking the pathways. Another view holds: Belching accompanied by swallowing sour fluid is due to food stagnation generating excessive heat and fire, with Qi rushing upward. In such cases, Scutellariae Radix (Huangqin) should be the sovereign drug, with Arisaematis Rhizoma Preparatum (Nanxing), Pinelliae Rhizoma (Banxia), and Citri Reticulatae Pericarpium (Chenpi) as assistant drugs.
Prescription: Evodiae Fructus (Wuzhuyu) (30g, remove stems and branches, boil briefly, soak for half a day, dry), Atractylodis Macrocephalae Rhizoma (Cangzhu) (soaked in rice washing water), Coptidis Rhizome (Huanglian) (30g, stir-fried with soil from old walls, remove soil), Scutellariae Radix (Huangqin) (30g, stir-fried with soil as above), Citri Reticulatae Pericarpium (Chenpi) (each 30g). Alternatively, add Platycodonis Radix (Jiegeng) 30g and Poria (Fuling) 30g. Grind into powder, make pills with Medicated Leaven paste (Shenqu), size of mung beans. Take 20–30 pills at a time, allowing saliva to wash them down frequently.