Xia Ku Cao (Prunella or Selfheal Spike)

Chinese Herb Actions

Chinese Herb Dosage

• What is the typical dosage of Xia Ku Cao?

  Commonly 9–15 g in decoction, up to about 30 g when used as a single herb, the range given in Sacred Lotus sources & references and consistent with standard materia medica.

  • Part used — the dried fruiting spike (the whole flowering head after it has browned and dried).
  • Honey-processed (zhi) form — toasting Xia Ku Cao with honey softens its cold, draining edge and is traditionally used for long-term management of high blood pressure where ongoing use is intended.

  Source: Sacred Lotus sources & references; cross-referenced against multiple online sources. Reference only — not a prescription.

Chinese Herb Contraindications & Cautions

• Are there cautions for Xia Ku Cao?

  Caution is advised in patients with a weak Spleen and Stomach. As a bitter, cold herb, Xia Ku Cao can aggravate poor digestion, loose stools, or low appetite if used at high dose or for a prolonged period without Stomach-protective combination herbs.

  • Spleen/Stomach deficiency — use cautiously; combine with digestion-supporting herbs for extended courses.
  • Long-term/high-dose use — the honey-processed form is traditionally preferred when ongoing use is intended, to soften its coldness.

  Source: Sacred Lotus sources & references; cross-referenced against multiple online sources.

Western / Biomedical Research

Chinese Herb Clinical Studies & Research

Provided as research context — a summary of published biomedical study, not a therapeutic or medical claim.

• Is there modern research on Xia Ku Cao (Prunella vulgaris)?

  Yes — a notable line of modern research has examined Prunella vulgaris specifically in thyroid conditions, which parallels its long-standing traditional use for neck nodules and goiter. This is offered as research context, not a treatment recommendation, and does not establish Xia Ku Cao as a substitute for conventional thyroid care.

  • Thyroid nodules (meta-analysis) — a meta-analysis of randomized controlled trials found that adding a Prunella vulgaris preparation to standard thyroid medication was associated with a higher clinical-effectiveness rate and modestly reduced nodule size versus medication alone, while noting the underlying trial quality was uncertain and higher-quality studies are needed.
  • Autoimmune thyroid disease (preclinical) — animal and cell studies report that Prunella vulgaris (and its constituent rosmarinic acid) reduced thyroid inflammation and autoantibody markers in models of experimental autoimmune thyroiditis, and separately helped rebalance immune cell populations in models of Graves' disease.
  • Review literature — a 2022 review summarizes an emerging body of work on Prunella vulgaris across goiter, nodules, and autoimmune thyroid disease, concluding the evidence is promising but still developing.

  Overall, this is a genuinely active modern research area for the herb, but clinical evidence remains preliminary and should not be read as validating any specific therapeutic use.

  Sources: PMID 34731129 (meta-analysis, thyroid nodules); PMID 34764638 (experimental autoimmune thyroiditis, preclinical); PMID 38879922 (Graves' disease mechanism, preclinical); PMID 36118009 (review, Chinese Herbal Medicine). Research context, not a therapeutic claim.

Chinese Herb Notes

• Why is Xia Ku Cao called the "herb that withers in summer"?

  Xia Ku Cao literally means "summer-dries-out herb" — classical materia medica sources describe the plant's spike sprouting through winter and spring and then withering as full summer heat arrives, an observation traditionally used to explain its therapeutic character. Growing during the yin (cold) half of the year and dying back exactly as yang (heat) peaks was read by classical physicians as the plant embodying a yin-within-yang quality — a rationale offered for why it can descend and drain excess Liver yang/fire while still being usable, in careful combination, even in some Liver-deficiency presentations.

  Note: This "withering in summer" explanation is a classical/traditional rationale recorded in materia medica literature, not a modern pharmacological finding; it is presented here as historical-classical context, not as an evidence claim.

  Source: Sacred Lotus sources & references, cross-referenced against multiple online sources (classical materia medica tradition).