通下行、补肝肾、散恶血。
苦酸而平。足厥阴、少阴经药。（肝、肾。）能引诸药下行。酒蒸。甘酸而温。益肝肾。
强筋
骨。（肝主筋、肾主骨。）治腰膝骨痛。足痿筋挛。阴痿。（血行故痛止、下行故理足、补
肝则筋舒、筋舒则阴强。）久疟。（以上皆补肝肾之功。）生用散恶血。破症结。（血行则结散
。）治心腹诸痛。淋痛尿血。（热蓄膀胱、便涩而痛曰淋、气淋便涩余沥、劳淋房劳即发、冷
淋寒战后溲、膏淋便出如膏、石淋精结成石、血淋涩痛、尿血色鲜者、心与小肠实热、色瘀
者、肾与膀胱虚冷、子和曰∶石淋乃肝经移热于胞中、日久熬煎成石、非肾与小肠病也、大
抵治淋、宜通气清心、平火利湿、不宜用补、恐湿热得补增剧也、牛膝淋证要药、血淋尤宜
用之、杜牛膝亦可、又有中气不足、致小便不利者、宜补中益气、经所谓气化则能出也、
忌用淋药通之。）经闭产难。（下行之效、误用堕胎。）喉痹齿痛。（引火下行。）痈肿恶疮。
金疮伤折。（以上皆散恶血之功。）出竹木刺。（捣烂罨之、即出、纵疮口合、刺犹自出。）有
升
主用皆在肾肝下部。上焦药中勿入。梦遗滑精。血崩不止。及气虚
下陷。因而腿膝肿痛者。大忌。出怀庆府。长大肥润者良。下行生用。入滋补药。酒浸蒸。
恶鳖甲。畏白前。忌牛肉。（口舌疮烂、牛膝浸酒、含漱、牙齿疼痛、煎汤冷漱。）
（牛膝的功效是）引导药力下行，补益肝肾，消散瘀血。
其味苦、酸，性平，归足厥阴肝经和足少阴肾经。（肝与肾。）能够引导其他药物向下行。用酒蒸制后，味甘、酸，性温，能补益肝肾。
强壮筋骨。（肝主管筋，肾主管骨。）治疗腰部和膝盖的骨骼疼痛，足部痿软无力及筋脉拘挛，阳痿。（因为血液运行通畅所以疼痛停止，药力下行所以调理足部，补益肝脏则筋脉舒展，筋脉舒展则阴茎勃起有力。）治疗久疟。（以上都是补益肝肾的功效。）生用可消散瘀血，破除癥瘕积聚。（血液运行则结块消散。）治疗心腹部各种疼痛，淋证疼痛及尿血。（热邪蓄积在膀胱，小便涩滞且疼痛称为淋证；气淋表现为小便涩滞且余沥不尽；劳淋因房劳过度而发作；冷淋表现为寒战之后排尿；膏淋表现为尿液排出如脂膏；石淋因精气凝结成石；血淋表现为涩痛；尿血色鲜红的，属于心与小肠实热；尿色暗紫的，属于肾与膀胱虚冷。张子和说：石淋乃是肝经的热邪转移至胞宫，日久煎熬而成结石，并非肾与小肠的疾病。大抵治疗淋证，宜通利气机、清心火、平降火势、利湿，不宜使用补法，恐怕湿热得到补益后病情加重。牛膝是治疗淋证的要药，血淋尤其适宜使用它，杜牛膝也可以。又有因中气不足导致小便不利的，宜补中益气，正如经典所说气化功能正常才能排尿，忌用通淋药物治疗。）治疗经闭及难产。（因其下行的功效，误用会导致堕胎。）治疗喉痹及牙齿疼痛。（引火下行。）治疗痈肿恶疮，金创及跌打损伤。（以上都是消散瘀血的功效。）取出竹木刺。（将牛膝捣烂敷贴患处，刺即可出来，即使疮口愈合，刺仍会自行排出。）
牛膝的主要作用都在肾肝所主的下部。在上焦用药中不要加入。梦遗滑精，血崩不止，以及气虚下陷因而导致腿膝肿痛者，大忌。产于怀庆府。长得长大肥润的为好。欲使其下行则生用，入滋补药则用酒浸或蒸制。
畏恶鳖甲，畏惧白前，忌食牛肉。（口舌生疮溃烂，用牛膝浸泡的酒含漱；牙齿疼痛，煎汤冷却后含漱。）
(Its functions are to) guide medicinal actions downward, tonify the Liver and Kidney, and dissipate evil blood (stasis).
Bitter and sour in flavor, neutral in nature. It enters the Foot Jueyin (Liver) and Foot Shaoyin (Kidney) meridians. (The Liver and Kidney.) It can guide various medicines downward. When steamed with wine, it becomes sweet and sour in flavor, warm in nature, and benefits the Liver and Kidney.
It strengthens tendons and bones. (The Liver governs the tendons, and the Kidney governs the bones.) It treats pain in the lower back, knees, and bones; flaccidity of the legs and tendon spasms; and impotence. (Because blood circulation improves, pain ceases; because the action descends, the feet are regulated; by tonifying the Liver, the tendons relax; when the tendons relax, sexual potency increases.) It treats chronic malaria. (All of the above are effects of tonifying the Liver and Kidney.) Used raw, it dissipates stasis and breaks up masses. (When blood circulates, accumulations disperse.) It treats various pains in the heart and abdomen, painful dysuria, and hematuria. (Heat accumulating in the Bladder causes difficult and painful urination, termed Lin syndrome. Qi-type Lin presents with difficulty and dribbling; Labor-type Lin is triggered by sexual exhaustion; Cold-type Lin involves chills before urination; Paste-type Lin involves discharge resembling paste; Stone-type Lin involves stones formed from essence condensation; Blood-type Lin involves painful difficulty. If urine is bright red, it indicates excess heat in the Heart and Small Intestine; if dark, it indicates deficiency-cold in the Kidney and Bladder. Zhang Zihe stated: Stone-type Lin results from heat transferring from the Liver meridian to the uterus, boiling over time to form stones, not a disease of the Kidney or Small Intestine. Generally, treating Lin syndrome should involve promoting Qi movement, clearing the Heart, calming fire, and promoting diuresis to remove dampness; tonification should be avoided as it may worsen damp-heat. Niuxi is a key herb for Lin syndrome, especially suitable for Blood-type Lin; Du Niuxi is also acceptable. In cases where insufficient Middle Qi causes difficult urination, one should tonify the Middle and augment Qi, as the classics state that Qi transformation enables excretion; avoid using herbs for draining Lin.) It treats amenorrhea and dystocia. (Due to its descending effect, misuse can cause abortion.) It treats throat obstruction and toothache. (Guiding fire downward.) It treats carbuncles, malignant sores, metal wounds, and fractures. (All of the above are effects of dissipating stasis.) It removes bamboo or wood splinters. (Mash and apply; the splinter will emerge, and even if the wound closes, the splinter will still come out.)
Its primary uses are in the lower parts governed by the Liver and Kidney. Do not include it in formulas for the Upper Jiao. It is strictly contraindicated in cases of nocturnal emission and spermatorrhea, continuous metrorrhagia, and Qi deficiency with sinking leading to swelling and pain in the legs and knees. It originates from Huaiqing Prefecture. Those that are large, long, and plump are superior. Use raw to promote descending action; use wine-soaked or steamed for tonifying formulas.
It is incompatible with Biejia (Tartaric Testudinis Carapax et Plastrum), fears Baiqian (Periplocae Radix), and avoids beef. (For mouth and tongue ulcers, rinse with wine-infused Niuxi; for toothache, rinse with cold decoction.)