通、大燥大泻。
辛而大热大毒。开窍宣滞。去脏腑沉寒。最为斩关夺门之将。（大黄巴豆、同为峻下之
剂、
但大黄性寒、腑病多热者宜之、巴豆性热、腑病多寒者宜之、故仲景治伤寒传里多热者、多
用大黄、东垣治五积属脏者、多用巴豆。）破痰癖血瘕。气痞食积。生冷硬物所伤。
大腹水肿泻痢。（时珍曰∶一妇年六十、溏泻五载、投生冷油腻肉食、即作痛、服升涩药、
泻反甚、脉沉而滑、此乃脾胃久伤、积食凝滞、法当以热下之、用蜡匮巴豆丸五十粒、服二
日、不利而愈、自是每用治泻痢、愈者近百人。）惊痫口 。耳聋牙疼喉痹。（缠喉急痹、缓
治则死、用解毒丸、雄黄一两、郁金一钱、巴豆十四粒、去皮油为丸、每服五分、津咽下、
雄黄破结气、郁金散恶血、巴豆下稠涎、然系厉剂、不可轻用、或用纸拈蘸巴豆油、然火刺
喉、或捣巴豆绵裹、随左右
纳鼻、吐出恶涎紫血、即宽、鼻虽少生疮、无碍。）杀虫。通经烂胎。油作纸拈。然火吹息。
或熏鼻。或刺喉。能出恶
涎
恶血。治中风中恶。痰厥气厥。喉痹不通。一切急病。元素曰。不可轻用。郁滞虽开。真阴
随损。以少许着肌肤。即起
泡。况肠胃柔薄之质。无论下后耗损真阴。即脏腑被其熏灼。能无溃烂之患耶。万不得已。
亦须炒熟去
或用壳用仁用油。生用炒用。醋煮。烧存性用。（好古曰∶去心皮膜油、
生用、为急治水谷道路之剂、炒去烟、令紫黑用、为缓治消坚磨积之剂、可以通肠、可以止
泻也。）去油名巴豆霜。芫花为使。畏大黄、黄连、凉水。（中其毒者、以此解之、或黑豆绿
豆汁、亦佳。）得火良。（疣痣黑子、巴豆一钱、锻石拌过、人信一钱、糯米五分、炒研点之
。）根皮、治痈疽发背。脑疽鬓疽。（掘取洗捣、敷患处、留头、妙不可言。收根阴干、临
时水捣、亦可。）
巴豆，药性通利、大燥、大泻。
味辛，性大热，有大毒。能开通窍道、宣通滞气。去除脏腑深处的寒邪。是最为猛烈的攻下将领。（大黄和巴豆，同属于峻猛的泻下剂型。但大黄性寒，腑病多属热证者适宜使用；巴豆性热，腑病多属寒证者适宜使用。所以张仲景治疗伤寒传入里部且多热证的病症时，多用大黄；李东垣治疗五积中属于脏病的病症时，多用巴豆。）
能破除痰癖、血瘕（腹内结块）。治疗气痞、食积。以及因生冷坚硬食物所致的损伤。
治疗大腹水肿、腹泻、痢疾。（李时珍说：有一位六十岁的妇女，患溏泄腹泻长达五年，一吃生冷油腻肉食就会疼痛，服用升提收敛的药物后，腹泻反而加重。脉象沉而滑，这是脾胃久已受伤，积食凝滞所致。治法应当用热性药物攻下。使用蜡壳包裹的巴豆丸五十粒，服用两天后，未引起剧烈腹泻而痊愈。从此以后每次用它治疗泻痢，治愈的近百人。）
治疗惊痫、口眼歪斜、耳聋、牙痛、喉痹。（缠喉急痹，若缓慢治疗则会致死。可用解毒丸，配方为雄黄一两、郁金一钱、巴豆十四粒，去皮去油制成丸药。每次服用五分，用唾液送服。雄黄破散结气，郁金消散恶血，巴豆排出稠厚涎液。然而这属于猛烈之剂，不可轻易使用。或者用纸捻蘸取巴豆油，点燃火苗吹灭后刺入喉咙，或将巴豆捣碎后用棉布包裹，根据病情左右塞入鼻孔，吐出恶涎和紫黑血液，症状即刻缓解。虽然鼻部可能少许生疮，但无妨碍。）
杀虫。通经堕胎。
巴豆油可作纸捻。点燃火苗吹熄。或熏鼻。或刺喉。能排出恶涎和恶血。治疗中风、中恶。痰厥、气厥。喉痹不通。一切急症。
王好古说：不可轻易使用。郁滞虽已开通，但真阴随之受损。只要少许接触肌肤，就会起泡。何况肠胃柔薄之质，无论泻下后耗损真阴，即使脏腑被其熏灼，难道没有溃烂的祸患吗？万不得已时，也必须炒熟去掉油，或者用壳、用仁、用油。有生用、炒用、醋煮、烧存性用法。（李杲说：去心皮膜油，生用，是紧急治疗水谷道路阻滞的剂型；炒至冒烟，令其呈紫黑色使用，是缓慢治疗消坚磨积的剂型，可以通肠，也可以止泻。）
去油后的巴豆称为巴豆霜。以芫花为使药。畏大黄、黄连、凉水。（中毒者，以此解之，或用黑豆绿豆汁，也很好。）得火则良。（治疗疣痣黑子，用巴豆一钱，与锻石拌过，加入人信一钱、糯米五分，炒研后点涂。）
巴豆根皮，治疗痈疽发背、脑疽鬓疽。（挖掘取出洗净捣碎，敷于患处，保留头部不敷，效果妙不可言。收集根皮阴干，临时用水捣碎，也可以使用。）
Badi Dou (Crotonis Fructus) has a penetrating, highly drying, and purgative nature.
It is acrid, extremely hot, and highly toxic. It opens orifices and disseminates stagnation. It removes deep-seated cold from the Zang and Fu organs. It is regarded as the most potent general for breaking through barriers and seizing gates. (Dahuang Rhizoma Rhei and Badi Dou are both drastic purgative formulas. However, Dahuang is cold in nature and suitable for Fu organ diseases that are mostly heat-patterns; Badi Dou is hot in nature and suitable for Fu organ diseases that are mostly cold-patterns. Therefore, Zhang Zhongjing used Dahuang frequently when treating Shanghan [Cold Damage] transmitted to the interior with heat patterns; Li Dongyuan used Badi Dou frequently when treating Wujie [Five Accumulations] belonging to Zang organ diseases.) It breaks down phlegm accumulation and blood masses (Xuejia, abdominal masses). It treats Qi pi [Qi obstruction], food retention, and injuries caused by raw, cold, hard substances.
It treats massive abdominal edema, diarrhea, and dysentery. (Shizhen said: A sixty-year-old woman suffered from loose stools for five years. Upon consuming raw, cold, greasy, or meat foods, she experienced pain. After taking ascending and astringent medicines, her diarrhea worsened. Her pulse was deep and slippery. This was due to long-term injury of the Spleen and Stomach, with retained food causing stagnation. The treatment method should be to purge using hot-natured herbs. She took fifty pills of Badi Dou coated with wax. After two days of administration, she recovered without experiencing severe diarrhea. Since then, I have used it to treat diarrhea and dysentery, curing nearly a hundred people.)
It treats fright-epilepsy, facial paralysis, deafness, toothache, and throat bi [obstruction]. (Chanting Hou Ji Bi [strangling throat acute bi], if treated slowly, leads to death. One can use Jiedu Wan [Detoxification Pill], composed of Xionghuang Realgar (1 liang), Yujin Curcuma Radix (1 qian), and Badi Dou (14 grains, peeled and oil removed), made into pills. Take 0.5 qian per dose, swallowed with saliva. Xionghuang breaks up stagnant Qi, Yujin disperses foul blood, and Badi Dou expels thick phlegm. However, this is a harsh agent and must not be used lightly. Alternatively, dip a paper wick in Badi Dou oil, ignite it, blow it out, and prick the throat. Or crush Badi Dou, wrap it in cotton, and insert it into either nostril according to the side affected, expelling foul phlegm and purple blood, providing immediate relief. Although minor sores may appear in the nose, it causes no harm.)
It kills parasites. Unblocks menstruation and induces abortion.
The oil can be made into paper wicks. Ignite and extinguish. Or fumigate the nose. Or prick the throat. It can expel foul phlegm and foul blood. It treats Zhongfeng [Wind Stroke], Zhong'e [Sudden Evil Invasion], Tan Jue [Phlegm Syncope], Qi Jue [Qi Syncope], unblocked throat bi, and all acute conditions.
Wang Haogu said: It must not be used lightly. Although stagnation is opened, True Yin is damaged along with it. If even a tiny amount touches the skin, blisters will arise. How much more so for the delicate and thin tissues of the intestines and stomach? Regardless of the depletion of True Yin after purging, even if the Zang and Fu organs are scorched by its heat, could they avoid the risk of ulceration? Only when absolutely necessary should one stir-fry it to remove the oil, or use the shell, the kernel, or the oil. Methods include raw use, stir-fried use, vinegar-boiled use, and burning to retain its character. (Li Gao said: Removing the heart, skin, membrane, and oil, and using it raw is an urgent remedy for water and grain pathway obstruction; stir-frying until smoke rises until it turns purple-black is a mild remedy for dissolving hardness and grinding away accumulations; it can unblock the intestines and also stop diarrhea.)
Badi Dou after oil removal is named Badoushuang (Crotonis Fructus Frost). Yuanhua Genkwan Flower Bud is its guiding herb. It is inhibited by Dahuang, Huanglian Coptidis Rhizoma, and cold water. (In case of poisoning, these can resolve it; or black soybean and mung bean juice are also good.) Fire benefits it. (For treating warts, nevi, and black spots: mix 1 qian of Badi Dou with calcined alkali, add 1 qian of Renxin Alum and 0.5 qian of glutinous rice, stir-fry, grind, and apply locally.)
The root bark treats Yongju [boils and carbuncles], Fabei [back carbuncle], Naoju [brain carbuncle], and Binju [temple carbuncle]. (Dig up, wash, crush, and apply to the affected area, leaving the head uncovered. The effect is indescribably excellent. Collect the root bark, dry it in the shade, and crush it with water when needed for use.)