Achyranthis Root
牛膝 · Niú Xī
Eases hot, swollen, aching knees and lower legs
Properties
NeutralNeutral botanicalBitter, Sour
Concerns
What it does
Achyranthis root works downward, guiding qi, your body's vital energy, and blood toward the lower body. That is why it clears damp-heat pooled in the knees and legs, and why it sits in Four-Marvel Pill for numb, weak legs. The same downward pull draws rising fire back down, easing dizziness and nosebleeds. Prepared, it tonifies the Liver and Kidneys and strengthens sinews and bones.
Safety
- Contraindicated during pregnancy or in those with excessive menstruation.
- Documented uterine stimulant. This is why pregnancy is ruled out rather than just cautioned.
- AHPA Safety Class 2b and 2d: not for use in pregnancy or excessive menstruation without supervision.
- The unprepared form can aggravate downward leakage: seminal emission, vaginal discharge, or diarrhea.
- If you have those symptoms, use the prepared form (zhì niú xī) or skip the herb entirely.
- Generally well tolerated at standard doses. Prepared form (zhì niú xī) tonifies; raw form moves blood stasis.
How to take it
Decoct 6–15g in 3 cups for 25–30 minutes. Strain and drink warm. Mostly used inside formulas. Unprepared moves blood stasis; prepared (zhì niú xī) tonifies, so check which one you have.
Use as part of Four-Marvel Pill teapills rather than as a standalone decoction unless directed by a practitioner
Where it comes from
Achyranthis root appears in the Divine Husbandman's Classic of the Materia Medica and has been used for thousands of years. Achyranthes bidentata is the standard species, cultivated primarily in Henan province. The name ox knee comes from the swollen leaf nodes along the plant's stem, which look like an ox's knees, though it is the root that is used as medicine. Its downward-directing action made it a staple of both blood-moving and heat-clearing prescriptions.