Xian Mao (仙茅; Xiān Máo; Latin: Curculiginis Rhizoma; English: common curculigo rhizome) is the dried rhizome of a small perennial herb of the lycoris family that grows in rock crevices and waste slopes of southern hills — a brownish, finely wrinkled root dug in autumn by older folk and sun-dried for gentle daily care. It is warm, acrid with a slight bitter note, enters the Kidney and Liver channels (with the Spleen in some records), and its core actions are to warm and supplement the kidney yang, and to expel cold and damp. It is the gentle winter root for cold limbs and a cold low back. The usual amount is 3–10 g in a decoction, or 3–5 g as a food remedy. It is a medicinal piece, not a food to add to daily meals.
It is not Yin Yang Huo. Epimedium is also warm, acrid, and sweet — it supplements the kidney yang and strengthens the sinews and bones, better for kidney deficiency with weak bones and limbs; this curculigo rhizome is warm, acrid, and slightly bitter — it warms the kidney yang and expels cold-damp, better for cold-damp joint and limb pain. It is not a general tonic; it acts within clear patterns. In yin-deficiency with fire — dry mouth, tidal heat, night sweats — using it on your own is a poor match. Long-standing joint pain with swelling and heat, or weakness that keeps worsening, needs a clinic first. Do not take it yourself for a long time.
It is used most often for three patterns:
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Kidney yang insufficiency — fear of cold and cold limbs, sore weak low back and knees, frequent long clear urine — after long sitting or too much cold drink
- Cold-damp blockage — cold pain of the limbs and joints, hard to bend and stretch, worse in cold, cold hands and feet
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Yin-deficiency with fire — dry mouth, tidal heat, night sweats — or heat-type joint pain — seek care / skip it
Warm, acrid, and warm-drying, it is not a daily "kidney-warming root" to keep increasing. Warming when there is no yang deficiency, or in a yin-deficient body, feeds the heat instead of helping.
When long sitting, cold drink, and age drain the kidney yang — the limbs run cold, the low back aches, the knees weaken, the urine comes long and clear — the body needs a gentle warm-and-build rather than a strong purge. Xian Mao is warm, acrid, and slightly bitter. It warms the kidney yang and expels cold-damp, which is why it appears in Er Xian Tang (Two Immortals Decoction)–type formulas. It warms more than it pushes. In yin-deficiency with fire, more makes it worse.
Xian Mao is not a catch-all kidney or cold root. In yin-deficiency with fire, in pregnancy, or without yang deficiency and cold-damp, using it alone is a poor match. Whether it belongs in a formula, and at what dose, should be decided by a licensed Chinese medicine practitioner after pattern diagnosis.