（见肺部）
〔害〕下焦血分湿热之要药。然其性悍气猛，走窜决防，苦伤胃。凡胃虚阴虚，自汗盗
汗，
口苦舌干，肾虚小水不利，及胎前产后血虚，虽有下焦湿热，慎勿用之。
东垣云∶防己大苦大寒，泻血中湿热，亦瞑眩之药也，服之使人心身烦乱，饮食减少。
若虚
人用防己，其害有三∶谷食已亏，复泄大便，则重亡其血，此不可用，其害一也；如人大渴
引饮，是热在上焦肺经气分，而防己乃下焦血分药，此不可用之者，其害二也；外伤风寒邪
传肺经气分而小便黄赤，乃至不通，此上焦气病，禁用血药，此不可用者，其害三也。大抵
上焦湿热者，皆不可用也。
〔利〕苦辛寒，入膀胱，亦通行十二经。祛下焦血分之湿热，通二便，木防己用治风症。
〔修治〕二八月采阴干，以车前草根相对蒸半日，晒干用。今惟去皮锉，酒洗晒干用。
（见心部）
（见肺部）
（见肾部）
（见前）
〔害〕升浮之性，易动肝木。若似中风，产后血晕痉急诸病，头痛因于血虚不因于风寒，
泄
泻不因于寒湿，及二便闭涩，小儿脾虚发搐，慢惊脾风，气升作呕，火升作嗽，阴虚盗汗，
阳虚自汗等病，法所同忌。能泻肺实，误服泻人上焦元气。叉头者，令人发狂，叉尾者，发
人痼疾。
〔利〕甘辛温，入肺膀胱二经。治大风恶风，风邪周痹，头面浮风，眼赤，多泪，能防
御外
风，故名。卑贱之职，随所引而至，乃风药中之润剂也。
〔修治〕青州黄润者良，软芦糯体。登州莱阳次之，关东者性硬，不佳。十二月采根，
曝干
切用。
（见肺部章节）
〔危害〕是治疗下焦血分湿热的关键药物。然而，它的药性猛烈，走窜力强，容易损伤胃气。凡是胃气虚弱、阴液不足、自汗或盗汗、口苦舌干、肾气虚导致小便不利，以及孕妇和产后血虚者，即使患有下焦湿热，也务必谨慎使用，不可轻易服用。李东垣说：防己味大苦大寒，能泻除血中的湿热，也是一种会引起剧烈反应（瞑眩）的药物，服用后会使人心烦意乱、身体不安、食欲减退。如果体虚之人使用防己，其危害有三点：一是饮食已经亏虚，再通泄大便，就会严重耗伤血液，这是不可用的，危害之一；二是如果人大渴引饮，说明热邪在上焦肺经的气分，而防己是作用于下焦血分的药物，病位不符，这是不可用的，危害之二；三是外感风寒邪气传入肺经气分导致小便黄赤甚至不通，这属于上焦气分病变，禁用血分药物，这也是不可用的，危害之三。大体来说，上焦湿热者都不可使用防己。
〔功效〕味苦、辛，性寒，归膀胱经，也能通行十二经脉。能祛除下焦血分的湿热，通利大小便，木防己用于治疗风症。
〔炮制〕农历二月和八月采集，阴干，用车前草根相对蒸半天，晒干后使用。现在只去除外皮切碎，用酒洗后晒干使用。
（见心部章节）
（见肺部章节）
（见肾部章节）
（见前文）
〔危害〕具有升浮的特性，容易扰动肝木。如果是类似中风、产后血晕、痉挛急迫等各种病症，头痛是由于血虚而非风寒引起，腹泻不是由于寒湿引起，以及大小便闭塞涩滞，小儿脾虚引发的抽搐、慢惊脾风，气机上逆导致的呕吐，火气上炎导致的咳嗽，阴虚盗汗，阳虚自汗等疾病，都在禁忌之列。它能泻肺实，误服会泻伤人上焦的元气。根部有叉头的，令人发狂；根部有叉尾的，诱发顽固性疾病。
〔功效〕味甘、辛，性温，归肺、膀胱二经。治疗大风恶风、风邪引起的周身痹痛、头面部浮肿之风邪、眼睛发红、多泪，能防御外风入侵，因此得名“防风”。它像地位低微的仆役，随引经药到达所需之处，是风药中的润剂。
〔炮制〕青州产的黄润、芦头软糯者为佳。登州莱阳产的次之，关东产的质地坚硬，不佳。十二月采集根部，曝晒干燥后切片使用。
(See section on Lung)
[Harm] It is a crucial herb for treating damp-heat in the blood aspect of the Lower Jiao (Lower Burner). However, its nature is fierce and potent, with strong dispersing and penetrating properties, which can bitterly damage Stomach Qi. For those with deficient Stomach Qi or Yin deficiency, spontaneous sweating or night sweats, bitter taste in the mouth and dry tongue, kidney deficiency leading to difficult urination, as well as women during pregnancy or postpartum with blood deficiency, even if they suffer from damp-heat in the Lower Jiao, one must be extremely cautious and avoid using it. Li Dongyuan stated: Fangji (Stephaniae Tetrandrae Rhizoma) is extremely bitter and cold, draining damp-heat from the blood; it is also a drug that causes severe adverse reactions (Mingxuan reaction), making the patient feel mentally restless and physically uncomfortable, with reduced appetite. If used by deficient individuals, there are three harms: First, if food intake is already insufficient, further purging the bowels will severely deplete blood; this is unusable, Harm One. Second, if a person is excessively thirsty and drinks much water, the heat is in the Qi aspect of the Upper Jiao Lung Meridian, whereas Fangji acts on the blood aspect of the Lower Jiao; this mismatch makes it unusable, Harm Two. Third, if external wind-cold pathogens transmit to the Qi aspect of the Lung Meridian causing yellow-red or obstructed urine, this is a Qi disease of the Upper Jiao, where blood-acting drugs are contraindicated; this is also unusable, Harm Three. Generally speaking, those with damp-heat in the Upper Jiao should not use it.
[Benefit] Bitter, pungent, and cold in nature, entering the Bladder Meridian, and also circulating through the Twelve Meridians. It dispels damp-heat in the blood aspect of the Lower Jiao and unifies the two bowels (urine and feces); Mu Fangji (Stephaniae Membranaceae Rhizoma) is used to treat wind disorders.
[Processing] Harvested in the second and eighth lunar months, dried in the shade. Steamed for half a day with roots of Plantago asiatica (Cheqiancao), then sun-dried. Currently, only the skin is removed, sliced, washed with wine, and sun-dried.
(See section on Heart)
(See section on Lung)
(See section on Kidney)
(See above)
[Harm] Its ascending and floating nature easily stirs Liver Wood. It is contraindicated in conditions resembling stroke, postpartum blood syncope, spasms and urgency, headache due to blood deficiency rather than wind-cold, diarrhea not caused by cold-dampness, constipation and urinary retention, pediatric convulsions due to Spleen deficiency, slow convulsive wind-spleen, vomiting due to rising Qi, cough due to rising Fire, yin-deficiency night sweats, and yang-deficiency spontaneous sweating. It can drain Lung excess; mistaken use will drain the Yuan Qi (Original Qi) of the Upper Jiao. Roots with forked heads cause madness; roots with forked tails induce chronic stubborn diseases.
[Benefit] Sweet, pungent, and warm in nature, entering the Lung and Bladder meridians. It treats severe wind aversion, wind-pathogen induced generalized bi-syndrome, wind swelling of the head and face, red eyes, and excessive tearing. It defends against external wind, hence its name "Fangfeng" (Wind Blocker). Like a humble servant, it reaches wherever guided by other herbs; it is a moistening agent among wind-dispersing drugs.
[Processing] Those from Qingzhou that are yellow, moist, with soft rhizomes and glutinous texture are superior. Those from Laiyang, Dengzhou are inferior. Those from Guandong are hard and poor quality. Harvest roots in the twelfth lunar month, sun-dry, and slice for use.