水蛭（三十个熬） 虻虫（三十个熬去翅足） 桃仁（二十个去皮尖） 大黄（三两酒浸）
上四味。锉如麻豆。以水五升。煮取三升。去滓。温服一升。不下。再服。
成氏明理论云。人之所有者。气与血也。气为阳。气留而不行者。则易散。以阳病易治故也。血为阴。血蓄而不
行者。则难散。以阴病难治故也。血蓄于下。非大毒驶剂。则不能抵当其甚邪。故治蓄血。曰抵当汤。水蛭味咸苦微寒。
内经曰。咸胜血。血蓄于下。胜血者。必以咸为主。故以水蛭为君。虻虫味苦微寒。苦走血。血结不行。破血者必以苦
为助。是以虻虫为臣。桃仁味苦甘平。肝者血之源。血聚则肝气燥。肝苦急。急食甘以缓之散血缓急。是以桃仁为佐。
大黄味苦寒。湿气在下。以苦泄之。血亦湿类也。荡血逐热。是以大黄为使。四物相合而方剂成。病与药对。药与病宜。
虽苛毒重疾。必获全济之功矣。
太阳病身黄脉沉结。少腹硬。小便不利者。为无血也。小便自利。其人如狂者。血证谛也。抵当汤主之。（太阳病身
黄者。膀胱热结。湿气不行。土主湿而色黄。湿热相搏。故身发黄也。脉沉为里证。结者。脉来缓时。一止复来之名也。
脉缓为湿。所以里湿之脉。当见沉结。少腹硬。则湿热之形。已蓄于下焦可知。上三证者。犹不分溺之与血。以血亦湿
润之物也。故当于小便验之。如小便不利者。为溺蓄于膀胱之内。而无血也。若小便自利。其人如狂者。乃血蓄于膀胱
以外为甚谛。谛者。审也。犹言精审。而无差也。仲景法。与抵当汤以下蓄血。按上文云。小便不利者。仲景不言治法。
成注云。可与茵陈汤。补亡论云。与五苓散。后条辩云。属茵陈五苓散。愚以三方可选而用之。）
伤寒有热少腹满。应小便不利。今反利者。为有血也。当下之。不可余药。宜抵当丸。（伤寒有热者。谓里有热。热
入下焦。故少腹作满形也。夫曰满。比急结稍甚。比硬稍轻。欲审其蓄血之证。亦须于小便验之。据病患小腹满。应当
小便不利。今反利者。为有蓄血也。当下之。然下之。不可用其余汤药。盖以桃核承气则太轻。抵当汤又太峻。成注云。
此无身黄发狂等证。是未至于甚。可与抵当丸小可下之。盖药味虽同。杵分为丸。一以缓其性。一以小其制也。）
Leech (Shuizhi, Hirudo nipponica), thirty pieces, processed by stir-frying;
Stablefly (Mengchong, Volucella bombylans), thirty pieces, processed by stir-frying with wings and legs removed;
Peach Kernel (Taoren, Prunus persica seed), twenty pieces, skin and tip removed;
Rhubarb Root and Rhizome (Dahuang, Rheum palmatum root and rhizome), three liang, soaked in wine.
The above four ingredients. Chop into pieces the size of hemp seeds or beans. Add five sheng of water, decoct to obtain three sheng of liquid. Strain off the dregs. Take one sheng warm. If the blood stasis is not expelled, take another dose.
Cheng Wuji stated in his "Ming Lilun" (Theory of Clarity): The substances possessed by the human body are primarily Qi and Blood. Qi belongs to Yang; when Qi stagnates and fails to circulate, it tends to dissipate easily because Yang diseases are easier to treat. Blood belongs to Yin; when Blood accumulates and fails to circulate, it is difficult to dissipate because Yin diseases are harder to treat. When Blood accumulates in the lower jiao, only a potent and fast-acting agent with strong toxicity can counteract such severe pathogenic factors. Therefore, the treatment for Blood Accumulation is named Didang Tang (Resisting Blood Decoction). Leech has a salty and bitter taste, and is slightly cold. The "Neijing" states that salty flavor can break Blood. Since Blood accumulates in the lower jiao, agents that break Blood must primarily use salty flavor; thus, Leech is used as the Sovereign drug. Stablefly has a bitter taste and is slightly cold. Bitter flavor enters the Blood level. When Blood coagulates and fails to move, agents that break Blood must assist with bitter flavor; thus, Stablefly is used as the Minister drug. Peach Kernel has a bitter and sweet taste, and is neutral. The Liver is the source of Blood; when Blood gathers, Liver Qi becomes dry and urgent. The Liver dislikes urgency, and eating sweet food can relieve it to scatter Blood and alleviate urgency; thus, Peach Kernel is used as the Assistant drug. Rhubarb Root and Rhizome has a bitter taste and is cold. Dampness in the lower jiao is drained using bitter flavor. Blood also belongs to the category of dampness. It sweeps away Blood and drives out Heat; thus, Rhubarb Root and Rhizome is used as the Envoy drug. These four ingredients combined form the prescription. The disease matches the medicine, and the medicine suits the disease. Even in cases of severe toxicity and critical illness, complete recovery can certainly be achieved.
In Taiyang disease, if there is yellowing of the body, a deep and knotted pulse, hardness in the lower abdomen, and dysuria, this indicates no Blood stasis. If urination is spontaneous and free, and the patient exhibits a manic-like state, this is definitive evidence of a Blood syndrome. Didang Tang (Resisting Blood Decoction) should be administered. (Yellowing of the body in Taiyang disease is due to heat binding in the Bladder and failure of dampness to circulate. Earth governs dampness and its color is yellow; the interaction of dampness and heat causes the body to turn yellow. A deep pulse indicates a interior syndrome. A knotted pulse refers to a pulse that comes slowly and occasionally stops before resuming. A slow pulse indicates dampness; therefore, the pulse for interior dampness should appear deep and knotted. Hardness in the lower abdomen indicates that the manifestation of damp-heat has accumulated in the lower jiao. The above three symptoms do not yet distinguish between urine accumulation and blood stasis, as Blood is also a moist substance. Therefore, verification should be made through urination. If urination is obstructed, it indicates urine accumulation within the Bladder without Blood stasis. If urination is free and the patient is manic-like, it indicates that Blood stasis has accumulated outside the Bladder, which is very definitive. "Di" means examination, implying precise scrutiny without error. According to Zhang Zhongjing's method, Didang Tang (Resisting Blood Decoction) is used to purge Blood stasis. Regarding the previous text mentioning obstructed urination, Zhang Zhongjing did not specify a treatment. Cheng Wuji's commentary suggests Yinyin Tang (Artemisia Capillaris Decoction). The "Buwang Lun" suggests Wuling San (Five-Ingredient Powder with Poria). Later commentaries suggest Yinchen Wuling San (Artemisia Capillaris and Five-Ingredient Powder with Poria Combination). I believe any of these three formulas can be selected for use.)
In Shanghan (Cold Damage) with fever and fullness in the lower abdomen, urination should be obstructed; however, if it is now free, this indicates the presence of Blood stasis. It should be purged. Other decoctions should not be used; instead, Didang Wan (Resisting Blood Pill) is appropriate. (Fever in Shanghan indicates internal heat; heat entering the lower jiao causes the sensation of fullness in the lower abdomen. The term "fullness" is slightly more severe than "urgent knotting" but lighter than "hardness." To examine for Blood Accumulation, verification must also be made through urination. Based on the patient's lower abdominal fullness, urination should be obstructed; however, since it is now free, this indicates Blood stasis. It should be purged. However, when purging, other decoctions should not be used. This is because Taohe Chengqi Tang (Peach Pit and Barley Malt Decoction) is too mild, while Didang Tang (Resisting Blood Decoction) is too harsh. Cheng Wuji's commentary notes that this case lacks symptoms such as yellowing of the body or mania, indicating the condition has not reached a severe stage. Didang Wan (Resisting Blood Pill) can be used to gently purge. Although the ingredients are the same, they are pounded into pills: this serves to moderate the properties of the drugs and reduce the dosage.)