治蓄血少腹硬满。小便自利。
水蛭（熬黑。如无。以鲮鲤甲生漆涂炙代之。） 虻虫（去翅足。熬各三十枚。） 大黄（酒浸。一两。）
桃仁（去皮尖。三十枚。）
上四味。水煎去滓。取三升。温服一升。不下再服。按此与承气不同。承气用枳实、浓朴以利气。
此用水蛭、虻虫、桃仁以破血也。
抵当丸（玉函） 治蓄血小便自利。服汤不应。用此丸。
抵当汤本方用水蛭二十枚。虻虫二十五枚。余同汤方。杵细入蜜。分为四丸。以水一升。煮一丸。
取七合服之。 时当下血。若不下者更服。
变通抵当丸
抵当丸去水蛭。加 虫二十个。鸡血拌。瓦上焙干。余如本方。如欲缓攻。临卧时酒服。五丸至十丸。
瘀下。止后药。
下瘀血汤（金匮） 治妇人产后腹痛。有干血着脐下。
抵当汤去水蛭、虻虫。加 虫。（二十枚。熬。去足）
代抵当场丸 治虚人蓄血。宜此缓攻。
抵当汤去水蛭、虻虫。本方大黄用四两。（酒浸。）桃仁用二十枚。加芒硝、蓬术、穿山甲、归尾、
生地黄各一两。肉桂三钱。为末蜜丸。蓄血在上部者。丸如芥子。黄昏去枕仰卧。以津咽之。令
停喉以搜逐瘀积。在中部食远。下部空心。俱丸如梧子。百劳水煎汤下之。用归、地者。引诸药入血分也。
如血老成积。攻之不动。去归、地。倍蓬术、肉桂。
Treats blood stasis syndrome characterized by hardness and fullness in the lower abdomen. Urination is normal and unobstructed.
Shuizhi (Leech, *Hirudo nipponica*) (stir-fried until charred black. If unavailable, replace with Lingli Jia [Manis Pentadactyla scale] coated with raw lacquer and roasted.) Mengchong (Housefly larva, *Musca domestica* larva) (remove wings and feet, stir-fry, 30 each.) Dahuang (Rhubarb Root & Rhizome, *Rhei Radix et Rhizoma*) (soaked in wine, 1 liang.) Taoren (Peach Seed, *Persicae Semen*) (remove skin and tips, 30 seeds.)
The above four ingredients are decocted in water, strained, yielding 3 sheng of liquid. Take 1 sheng warm. If stool/blood does not pass, take another dose. Note: This formula differs from Chengqi Tang (Gastrointestinal Releasing Decoction). Chengqi Tang uses Zhishi (Immature Bitter Orange, *Citri Reticulatae Viridis Fructus*) and Houpo (Magnolia Bark, *Magnoliae Officinalis Cortex*) to promote Qi movement.
This formula uses Shuizhi, Mengchong, and Taoren to break up blood stasis.
Didang Wan (Didang Pill, from *Yufang Pian*) Treats blood stasis syndrome with normal urination. Use this pill when the decoction fails to produce results.
Didang Tang original formula uses 20 Shuizhi and 25 Mengchong; the rest are the same as the decoction. Pound finely, mix with honey, and divide into four pills. Decoct one pill in 1 sheng of water.
Take 7 he of the decoction. Blood should be expelled at this time. If not, take another dose.
Modified Didang Wan
Remove Shuizhi from Didang Wan, add Chong (Ground Beetle, *Mylabris*), 20 pieces, moistened with chicken blood, baked on a tile. The rest follows the original formula. For a milder purgative action, take with wine before bed. 5 to 10 pills per dose.
Stop subsequent medication once blood stasis is expelled.
Xiayuxue Tang (Decoction for Expelling Stasis Blood, from *Jingui Yaolue*) Treats postpartum abdominal pain in women due to dry blood adhering below the umbilicus.
Remove Shuizhi and Mengchong from Didang Tang, add Chong (Ground Beetle, *Mylabris*). (20 pieces, stir-fried, feet removed.)
Dai Didang Tang Wan (Substitute Didang Decoction Pill) Treats blood stasis in patients with deficiency constitution, suitable for mild purgation.
Remove Shuizhi and Mengchong from Didang Tang. Use 4 liang of Dahuang (soaked in wine) and 20 Taoren. Add Mangxiao (Mirabilite, *Natrii Sulfas*), Pengzhu (Curcuma Zedoary Rhizome, *Curcumae Zedoariae Rhizoma*), Chuanshanjia (Pangolin Scale, *Manis Pentadactyla Squama*), Guiwei (Angelica Sinensis Root Tip, *Angelicae Sinensis Radix*), Shengdihuang (Rehmannia Root, *Rehmanniae Radix Recens*) each 1 liang, and Rougui (Cinnamon Bark, *Cinnamomi Cortex*) 3 qian. Grind into powder, make pills with honey. For blood stasis in the upper part, make pills the size of mustard seeds. At dusk, lie supine without a pillow, swallow with saliva, letting the pill linger in the throat to search out and expel accumulated stasis. For the middle part, take after meals. For the lower part, take on an empty stomach. Make pills the size of wutong seeds. Administer with decoction of Bailao (Lamprey, *Petromyzon marinus*). Guizhi and Dihuang are used to guide other herbs into the blood level.
If the blood stasis has become old and fixed, resisting attack, remove Guizhi and Dihuang, and double the dosage of Pengzhu and Rougui.