Xian Mao (仙茅) — Curculigo Rhizome in TCM | Kidney Yang & Menopause

At a Glance

• Herb: Xian Mao
• Chinese name: 仙茅 (Xiān Máo)
• Latin name: Curculiginis Rhizoma
• Nature: Hot
• Taste: Acrid
• Meridian: Kidney / Liver / Spleen
• Category: Herbs that Tonify Yang
• Introduction: Xian Mao (仙茅, Curculigo orchioides rhizome) — ‘immortal grass’ — is a hot, pungent, and mildly toxic herb first recorded in the Tang dynasty Hai Yao Bencao, said to have been introduced from India via Buddhist trade routes. It warms Kidney Yang with considerable force, strengthens sinews and bones, and expels Cold-Damp — making it more aggressive in warming action than most Kidney tonics. It is best known in modern practice as the Yang component of Er Xian Tang (Two Immortals Decoction) for menopausal syndrome, paired with the Yin-nourishing Yin Yang Huo. Curculigoside A and cycloartane glycosides show estrogen-modulating, osteogenic, and immunostimulant effects in pharmacological studies.

Action

• Warms Kidney Yang vigorously — addresses impotence, cold limbs, urinary frequency, and spermatorrhea from severe Kidney Yang deficiency.
• Strengthens sinews and bones — used for lumbar and knee weakness with Cold-Damp Bi syndrome.
• Expels Cold-Damp — relieves joint pain aggravated by cold and damp, particularly in the lower back and lower extremities.
• Warms Spleen Yang (secondary) — addresses cold abdominal pain and diarrhea from Spleen deficiency Cold.

Clinical Application

• Kidney Yang deficiency: impotence, cold limbs, cold lower back, urinary incontinence, infertility from uterine Cold.
• Wind-Cold-Damp Bi syndrome: joint pain and stiffness worsened by cold and damp, with underlying Kidney deficiency.
• Menopausal syndrome with Kidney deficiency: hot flushes combined with cold lower back, fatigue, and palpitations — used in Er Xian Tang.
• Spleen Yang deficiency: cold epigastric pain, loose stools from Middle Jiao deficiency Cold.

Precautions

• Dose: 3–9 g; hot preparation recommended.
• Classified as mildly toxic (小毒) — do not exceed dose or use long-term without monitoring.
• Contraindicated in Yin deficiency with Heat, excess Fire, or internal Heat patterns — can cause mouth sores, epistaxis, and agitation.
• Contraindicated in pregnancy.
• Caution in patients with liver disease — hepatotoxic potential at high doses.
• Traditional instruction: do not consume with iron utensils or cow/ox products during course of treatment.

Formula

• Er Xian Tang (二仙汤): Xian Mao with Yin Yang Huo, Ba Ji Tian, Dang Gui, Huang Bai, and Zhi Mu — modern formula for menopausal syndrome combining Kidney Yang warming with Yin nourishment and Fire clearing.
• Xian Mao Wan (仙茅丸): Xian Mao with Yin Yang Huo and Rou Cong Rong — for Kidney Yang deficiency impotence and cold limbs.
• Combined with Du Huo and Qin Jiao for Cold-Damp Bi syndrome with underlying Kidney deficiency.

Combinations

• Xian Mao (仙茅) + Yin Yang Huo (淫羊藿) → Er Xian Tang (二仙汤) core pair — warm Kidney yang; treat menopausal syndrome, impotence, and lower back cold pain
• Xian Mao (仙茅) + Yin Yang Huo (淫羊藿) + Dang Gui (当归) + Ba Ji Tian (巴戟天) + Huang Bai (黄柏) + Zhi Mu (知母) → Er Xian Tang (二仙汤) full formula — warm Kidney yang, nourish Kidney yin, clear deficiency fire; treat menopausal hot flashes with cold lower back (paradoxical yin-yang deficiency)
• Xian Mao (仙茅) + Bu Gu Zhi (补骨脂) + Tu Si Zi (菟丝子) → reinforce Kidney yang; treat severe impotence and infertility
• Xian Mao (仙茅) + Du Huo (独活) + Wei Ling Xian (威灵仙) → warm Kidney, expel cold-damp; treat lower limb Bi syndrome
• Xian Mao (仙茅) + Fu Zi (附子) + Rou Gui (肉桂) → extreme yang warming for cold collapse; toxicity warning: Xian Mao is toxic — overdose causes mucosal irritation, tongue numbness, and liver damage; standard dose 3–10g decocted only; do not take raw; do not use long-term in large doses; contraindicated in pregnancy; contraindicated in yin deficiency with fire effulgence; three-herb comparison — Xian Mao vs Yin Yang Huo vs Ba Ji Tian: Xian Mao has the hottest nature and strongest yang-strengthening action but is most toxic — short-term use only; Yin Yang Huo is moderate in warmth with PDE5-inhibitor and anti-osteoporosis activity; Ba Ji Tian is mildest and most moistening — safe for long-term use; Er Xian Tang design principle: Xian Mao + Yin Yang Huo (warm yang) + Zhi Mu + Huang Bai (cool yin-fire) = bidirectional balance for climacteric

Pharmacological Effects

• Androgenic / testosterone-boosting
  • curculigoside — stimulate LH release from pituitary
  • increase testosterone synthesis in Leydig cells
  • increase 3β-HSD enzyme activity in testes
  • androgenic receptor partial agonist
  • significantly more potent androgenic activity than 淫羊藿 at equivalent dose
  • 二仙汤 RCT: increase serum testosterone and LH in hypogonadal men
• Anti-osteoporosis
  • curculigoside — stimulate osteoblast proliferation via BMP-2
  • inhibit osteoclast differentiation
  • increase BMD in ovariectomized models
  • comparable to 淫羊藿 for bone density improvement
• Immunostimulant
  • polysaccharides — activate macrophage, NK cell
  • increase IFN-γ, IL-2
  • anti-tumor immune surveillance
• Anti-aging
  • phenol glucosides — high antioxidant
  • reduce ROS
  • protect DNA
  • extend lifespan in C. elegans models
• Anti-tumor
  • curculigoside B — inhibit lung and liver cancer cell proliferation
  • induce apoptosis
  • polysaccharides — enhance anti-tumor immune response
• Neuroprotective
  • curculigoside — protect hippocampal neurons from oxidative stress
  • improve memory in aging models
• Hepatoprotective at low dose
  • curculigoside — anti-inflammatory in liver
  • CAUTION: hepatotoxic at high dose — dose-dependent hepatotoxicity reported

Classic Description

• Hai Yao Ben Cao: ‘Governs wind, warms and tonifies the lumbar spine and legs, settles and calms the five organs, strengthens sinews and bones, and promotes digestion.’
• Ben Cao Gang Mu: ‘Xian Mao, nature hot, tonifies the fire of the triple burner and life gate, supports bone marrow; treats cold-cramping painful obstruction of the lumbar spine and knees, impotence with cold essence, nocturia and enuresis in the elderly, undigested food, cold qi in men, cold pain in the heart and abdomen; turns white hair and prevents ageing.’
• Ben Cao Zheng Yi: ‘Xian Mao warms the Kidney and disperses cold — a drastic yang-strengthening agent; although without yin-benefiting function, it is acrid, dry, and greatly hot — contraindicated in yin deficiency.’
• Ben Cao Cong Xin: ‘Tonifies life-gate fire, strengthens sinews and bones, strengthens the memory, assists the spirit and mind, frees blood vessels, dispels wind-dampness, eliminates fright and fear, strengthens yang function, warms the lumbar spine and knees.’