去皮，酒洗用。恶细辛，畏萆 、女菀、卤碱，伏消石。治风宜木防己，治水宜汉
防己。
辛，苦而寒，无毒。足太阴、太阳经药。通行十二经。解脏腑之水气，泄经络之湿邪。
除脚
气之肿痛，退下焦之湿热。手足挛急之疾，关节肿痛之 。乃驱风逐水之要剂，为除湿解热
之灵丹。
出汉中川谷及黔中。二八月采根。其茎如葛蔓延，其根外白内黄，如桔梗内有黑纹。但
汉中
出者，破之文作车辐解，黄实而香，茎梗甚嫩，苗叶小类牵牛。折其茎一头吹之，气从中贯
如木通。他处者青白虚软，又有腥气，皮皱，上有丁足子，名木防己。或以木防己不任用，
而张仲景、孙思邈皆用之，是木防己亦可甚弃也。
肺痿喘嗽，汉防己末，水煎细呷。（验方第一。）
肺痿咯血，汉防己。葶苈为末，糯米汤下。（第二。）
霍乱吐利，防己、白芷末，新水下。（第三。）
目睛猝痛，酒浸为末，酒下。（第四。）
解雄黄毒，水煎服。（第五。）
小便淋涩，木防己、防风、葵子，水煎服。（第六。）
木防己汤 防己 石膏 人参 桂枝
治膈间支饮，喘满心下痞，面赤黎黑，脉沉紧者。（诸方第一。）
防己茯苓汤 防己 黄 桂枝 茯苓 甘草
水煎服。治皮水 肿，按之没指。（第二。）
防己黄 汤 防己 黄 白术 炙草 姜 枣
治风水皮肿，汗出脉浮。又治风湿相搏，关节沉痛，微肿恶风。（第三。）
Remove the skin and wash with wine. It is incompatible with Ephedrae Herba (Mahuang, 麻黄), fears Bletillae Rhizoma (Bixie, 萆薢), Polygala Root (Nüwan, 女菀), and Sal Natrii Sulfurati (Lujian, 卤碱), and can suppress Gypsum Fibrosum (Xiaoshi, 消石). For treating wind disorders, use Stephaniae Tetrandrae Caulis (Mu Fangji, 木防己); for treating water-dampness disorders, use Stephaniae Membranaceae Radix (Han Fangji, 汉防己).
Pungent, bitter, and cold in nature, non-toxic. It enters the Foot-Taiyin Spleen Meridian and Foot-Taiyang Bladder Meridian. It circulates through the twelve meridians. It resolves water qi within the zang-fu organs and drains damp-evil from the collaterals. It eliminates swelling and pain caused by jiaoqi (foot disease) and clears damp-heat from the lower jiao. For conditions involving spasms and cramps of the hands and feet, as well as joint swelling and pain, it is a crucial agent for expelling wind and driving out water, and a miraculous elixir for removing dampness and clearing heat.
It originates from the valleys of Hanzhong and Qianzhong. The roots are harvested in the second and eighth lunar months. Its stems spread like those of Puerariae Lobatae Radix (Gegen, 葛根). The root exterior is white and interior yellow, resembling the black striations inside Peucedani Radix (Jiegeng, 桔梗). However, Hanfangji produced in Hanzhong, when broken, reveals a radial pattern like chariot spokes; it is solid, fragrant, has very tender stems, and small leaves resembling Ipomoeae Nil Semen (Qianniu, 牵牛). If one end of the stem is broken and blown into, air passes through completely, similar to Akebiae Caulis (Mutong, 木通). Those from other regions are greenish-white, hollow, soft, have a fishy odor, wrinkled skin, and protrusions resembling "ding" feet on the surface; these are called Mu Fangji. Some discard Mu Fangji due to its lesser status, yet Zhang Zhongjing and Sun Simiao both used it, indicating that Mu Fangji should not be entirely abandoned.
For feiwei (lung atrophy) with wheezing and cough: Powder the Han Fangji, decoct in water, and sip slowly. (Verified Formula No. 1.)
For feiwei with hemoptysis: Use Han Fangji and Descurainiae Semen seu Lepidii Semen seu Lepidii Fructus (Tingli, 葶苈子), powdered, taken down with rice gruel. (Formula No. 2.)
For huoluan (cholera-like syndrome) with vomiting and diarrhea: Powder Fangji and Angelicae Dahuricae Radix (Baizhi, 白芷), taken down with fresh cool water. (Formula No. 3.)
For sudden eye pain: Soak in wine, powder, and take down with wine. (Formula No. 4.)
To resolve Xionghuang toxicity (realgar poisoning): Decoct in water and take. (Formula No. 5.)
For strangury with difficult urination: Use Mu Fangji, Saposhnikoviae Radix (Fangfeng, 防风), and Malvae Semen (Kuizi, 葵子), decoct in water and take. (Formula No. 6.)
Fangji Tang: Composed of Stephaniae Tetrandrae Caulis (Mu Fangji, 木防己), Gypsum Fibrosum (Shigao, 石膏), Ginseng Radix et Rhizoma (Renshen, 人参), Cinnamomi Ramulus (Guizhi, 桂枝).
Treats zhiyin (branching fluid retention) between the diaphragm, characterized by wheezing, chest fullness, epigastric stuffiness, reddish-black complexion, and a deep, tight pulse. (Primary Formula No. 1.)
Fangji Fuling Tang: Composed of Stephaniae Membranaceae Radix (Han Fangji, 汉防己), Astragali Radix (Huangqi, 黄芪), Cinnamomi Ramulus (Guizhi, 桂枝), Poria (Fuling, 茯苓), Glycyrrhizae Radix et Rhizoma (Gancao, 甘草).
Decoct in water and take. Treats pishui (skin edema), where pressing leaves an indentation that does not immediately rebound. (Formula No. 2.)
Fangji Huangqi Tang: Composed of Stephaniae Membranaceae Radix (Han Fangji, 汉防己), Astragali Radix (Huangqi, 黄芪), Atractylodis Macrocephalae Rhizoma (Baizhu, 白术), Prepared Glycyrrhizae Radix et Rhizoma (Zhi Cao, 炙草), Zingiberis Rhizoma Recens (Jiang, 姜), Jujubae Fructus (Zao, 枣).
Treats fengshui (wind-water edema) presenting with skin swelling, sweating, and a floating pulse. Also treats wind-dampness bi-syndrome with heavy joint pain, slight swelling, and aversion to wind. (Formula No. 3.)