Xia Ku Cao
StarPrunella vulgaris L.
Traditionally used for
- Headaches
- Dizziness
- Eye health
- Nose & throat
- Cough & breathing
- Colds & fever
- Digestion
- Bowel health
- Urinary & fluids
- Pain & joints
- Blood pressure
- Skin
Cautions & contraindications
- Bleeding disorders
☯ TCM Properties
Clears Liver Fire and drains Fire; Brightens the Eyes; Disperses stagnation and reduces nodules; Reduces Swelling
Traditional Chinese Uses
Xia Ku Cao (self-heal spike, prunella spike) is a bitter, cold herb with a primary affinity for the Liver — it clears Liver Fire, softens hardened masses, and anchors rising Liver Yang. It is used for red, painful eyes and blurred vision from Liver Fire, for dizziness and headache from Liver Yang rising (as seen in hypertension), and for cervical and thyroid nodules, goiter, and scrofula from Phlegm-Fire accumulation. It is widely consumed as a cooling tea in southern China, particularly during summer.
Western Herbalism Properties
Traditional Uses
Prunella vulgaris is one of the most widely used Native American medicinal plants, with documented use by the Iroquois, Cherokee, Blackfoot, Menominee, Ojibwa, Algonquin, Bella Coola, Catawba, Chippewa, Cree, Delaware, Mohegan, Quileute and Quinault among others (Moerman, Native American Ethnobotany Database, after Hamel and Chiltoskey 1975 and others). Recorded medicinal uses include dermatological aids, febrifuges (5 records), gastrointestinal aids, antidiarrheals, gynecological aids, orthopedic aids, pediatric aids, heart and eye medicines, burn dressings, throat aids, analgesics, antiemetics, blood medicines, cold and cough remedies, hemorrhoid remedies and panaceas, and as a psychological aid; the plant was also eaten as a vegetable in three records (NAEB summary of 50 use records).
Pharmacological Effects
- Hypotensive: Aqueous and 30% ethanolic extracts lowered blood pressure in anesthetized animals; i.v. decoction in dogs gave marked, short-lived falls with tachyphylaxis; oral/i.p. doses gave milder longer effects; attenuated by vagotomy; role of inorganic salts disputed.
- Antibacterial: Decoction inhibited dysentery, typhoid and proteus bacilli, Mycobacterium tuberculosis and Vibrio comma in vitro; feeding 5-7.5 g/kg slightly reduced lesions in tuberculous mice without changing mortality.
- Smooth muscle: 50% decoction strongly contracted isolated non-pregnant rabbit uterus (weak on pregnant uterus) and increased rabbit intestinal peristalsis, especially duodenum.
Source: Zhu YP. Chinese Materia Medica: Chemistry, Pharmacology and Applications. Harwood Academic, 1998, p. 120.
Relationships
Full-screen graph →Click a node for details · double-click to expand it · Ctrl/⌘ + scroll or two fingers to zoom and pan.
Botanical Description
Prunella vulgaris L. (Lamiaceae), known as self-heal or heal-all, is a low-growing herbaceous perennial of meadows, lawns, woodland edges and disturbed ground throughout the temperate Northern Hemisphere. It produces creeping rhizomes that root at the nodes and erect to ascending, four-angled, finely hairy stems 10 to 40 cm tall. The leaves are opposite, ovate to oblong-lanceolate, 2 to 6 cm long, with entire to slightly toothed margins, a rounded to truncate base and short petioles; the uppermost pair sits directly beneath the inflorescence. The flowers are crowded in a dense, cylindrical to ovoid terminal spike 2 to 5 cm long, subtended by broad, often purplish, ciliate bracts. Each flower is two-lipped, 1 to 1.5 cm long, typically violet-purple, occasionally pink or white, with a hooded upper lip and a three-lobed lower lip. After flowering, the persistent dried spike, brown and rattling, is harvested in summer and constitutes Xia Ku Cao in Chinese medicine.
Active Constituents
Rosmarinic acid
Caffeic acid depside (phenolic ester)Concentration: up to about 15.8 mg/g of dry aerial parts at full flowering, higher in leaf than stem; the marker compound used for quality control of Spica Prunellae
The principal phenolic of Prunella vulgaris and the compound the Chinese Pharmacopoeia assay is built around. It scavenges superoxide, suppresses lipid peroxidation and damps NF-kB-driven inflammatory signalling, which accounts for much of the anti-inflammatory and antioxidant activity attributed to the whole spike.
Ursolic acid
Pentacyclic triterpenoid (ursane type)Concentration: about 1.8 mg/g of dry aerial parts at full flowering
An anti-inflammatory and antiproliferative triterpene that, with oleanolic acid, carries much of the antitumour and hepatoprotective activity reported for triterpene-enriched fractions of the herb. Early pharmacological work also credits the pair with antihypertensive activity.
Oleanolic acid
Pentacyclic triterpenoid (oleanane type)Concentration: about 0.65 mg/g of dry aerial parts at full flowering
The oleanane counterpart of ursolic acid, present at roughly a third of its concentration. It contributes to the anti-inflammatory and hepatoprotective profile of triterpene fractions and is one of the constituents to which the herb's blood-pressure-lowering activity in animals has been attributed.
Prunellin
Anionic (sulfated) polysaccharideConcentration: isolated from the aqueous extract; content not standardised
An anionic polysaccharide first purified as the anti-HIV principle of the water extract. Related Prunella polysaccharide fractions block herpes simplex virus attachment by competing with cell-surface heparan sulfate for viral glycoproteins, which is the mechanistic basis of the herb's antiviral reputation and also the reason a heparin-like pharmacodynamic effect cannot be dismissed out of hand.
1,8-Cineole
Monoterpene ether (volatile oil constituent)Concentration: reported as roughly 45% of the volatile oil, with beta-pinene about 16% and alpha-phellandrene about 6%
The dominant component of the small volatile-oil fraction of the spike. It contributes the aroma and mild mucolytic and anti-inflammatory character of the fresh herb, but the volatile oil is largely lost in a long decoction and is not the basis of the drug's classical indications.
⚠ Drug Interactions
Antithyroid drugs (methimazole, carbimazole, propylthiouracil)
A 2025 systematic review of 17 randomised trials in 1366 hyperthyroid patients found that adding a Prunella vulgaris preparation to antithyroid drugs produced significantly greater falls in free T3 (SMD -0.98) and free T4 (SMD -0.82), a greater rise in TSH (SMD 0.71), and a greater fall in TSH-receptor antibody (SMD -1.11) than antithyroid drugs alone. The effect on the thyroid axis is therefore real and additive rather than theoretical, even though the mechanism is not fully worked out; experimental work in Graves' disease models attributes part of it to restoration of Tfh/Tfr balance and to luteolin.
Clinical note: This is a wanted effect when the two are prescribed together deliberately, but it means the antithyroid dose may need reducing. Recheck TSH, free T4 and free T3 four to six weeks after starting or stopping Xia Ku Cao rather than assuming the drug dose is still right.
Levothyroxine
A meta-analysis of 13 randomised trials in 1468 patients with thyroid nodules found that Prunella vulgaris added to levothyroxine reduced nodule diameter (MD -0.43) and improved response rates (RR 1.22), but also lowered free T3 (MD -1.99) and free T4 (MD -3.20) further than levothyroxine alone. In a patient on levothyroxine for replacement rather than for TSH suppression, that same effect works against the prescription.
Clinical note: Distinguish suppressive from replacement intent before combining. If a hypothyroid patient on levothyroxine starts Xia Ku Cao, monitor thyroid function and warn them not to stop or start the herb between tests without telling the prescriber.
Antihypertensive drugs (ACE inhibitors, ARBs, calcium channel blockers)
Total alkaloid fractions of compound Prunella preparations relax rat thoracic aorta concentration-dependently, and Prunella combined with Uncaria rhynchophylla lowered systolic pressure in spontaneously hypertensive rats with falls in angiotensin II and endothelin and a rise in CGRP. Ursolic and oleanolic acid have separately been credited with antihypertensive activity. The evidence is animal and ex vivo — there are no controlled human blood-pressure trials of the single herb — so the interaction is plausible rather than demonstrated in patients.
Clinical note: Xia Ku Cao is commonly given for Liver-Fire headache in patients who are also hypertensive and treated. Check lying and standing blood pressure at the next visit after starting it rather than assuming no effect.
Insulin and oral hypoglycaemic drugs
Active fractions of Prunella vulgaris lowered blood glucose and produced antinociceptive effects in alloxan-induced diabetic mice, and polyphenols of the herb inhibit alpha-glucosidase in vitro. Both are animal or in vitro findings; no human glucose data exist for the herb alone.
Clinical note: No routine action needed, but a diabetic patient starting a high dose of Xia Ku Cao should be told to keep monitoring capillary glucose for the first week or two.
Heparin, warfarin and direct oral anticoagulants
The antiviral principle of the water extract is an anionic, sulfate-bearing polysaccharide that behaves like heparan sulfate — Prunella polysaccharide is pulled down by heparin beads and competes with cell-surface heparan sulfate for viral glycoproteins. Sulfated polysaccharides as a chemical class can carry heparin-like anticoagulant activity, but this has not been measured for prunellin and no bleeding events have been reported with the herb.
Clinical note: Do not withhold the herb on this basis alone, but if a patient on an anticoagulant is taking large amounts of a water extract or a concentrated polysaccharide product, an extra INR or clinical bleeding check is reasonable.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 9–15 g | Daily | — | — | 中国药典 2020 【用法与用量】9～15g。 【性味与归经】辛、苦，寒。归肝、胆经。 — Chinese Pharmacopoeia 2020, quoted verbatim; route and cautions preserved. Replaces a cleared category-filler value. |
Dui Yao — Herb Pairs
The classical two-herb combinations this herb appears in, each with an action neither herb has alone.
Xia Ku Cao withers as yang peaks at midsummer while Ban Xia grows as yin begins; the pairing draws on this to harmonize yin and yang and restore sleep, while clearing Liver heat and transforming phlegm.
Insomnia from phlegm-heat or yin and yang failing to communicate.
Named pairing — Lü Jingshan, Shi Jinmo Dui Yao; the pair is recorded in Leng Lu Yi Hua citing Yi Xue Mi Zhi
Evidence Tier
Strong evidence · 6 studiesRecorded studies by study design, strongest design at the top. This is a study-design tier only, not a GRADE rating: it does not weigh risk of bias, consistency or precision.
Systematic review / meta-analysis
2
2 verified · 0 unverified
Randomized controlled trial
0
Other clinical trial
0
Observational / case report
0
In vitro / animal
4
2 verified · 2 unverified
Show 4 studies
- Mechanism of Prunella vulgaris L. and luteolin in restoring Tfh/Tfr balance and alleviating oxidative stress in Graves' disease
- Prunella vulgaris polysaccharide inhibits herpes simplex virus infection by blocking TLR-mediated NF-κB activation
- The Antitumour Effect of Prunella vulgaris Extract on Thyroid Cancer Cells In Vitro and In Vivo
- Prunella vulgaris L. active components and their hypoglycemic and antinociceptive effects in alloxan-induced diabetic mice
Other / unclassified
0
Verified: design read from PubMed for a DOI that resolves to the cited paper Unverified: taken from the study's recorded description
Clinical Studies
Efficacy and safety of Prunella vulgaris L. combined with antithyroid drugs for hyperthyroidism: a systematic review and meta-analysis
Seventeen randomised controlled trials with 1366 hyperthyroid patients were pooled. Prunella vulgaris preparations added to antithyroid drugs outperformed antithyroid drugs alone for free T3 (SMD -0.98), free T4 (SMD -0.82), TSH (SMD 0.71) and TSH-receptor antibody (SMD -1.11), all P < 0.00001, and were associated with fewer adverse events (RR 0.34); relapse rates were comparable. The trials were Chinese-language and of uncertain methodological quality, so the direction of effect is more secure than the effect size.
Safety and efficacy of Prunella vulgaris preparation in adjuvant treatment of thyroid nodules
Thirteen randomised trials with 1468 patients with thyroid nodules were meta-analysed. Prunella vulgaris added to levothyroxine improved the clinical response rate (RR 1.22, 95% CI 1.11 to 1.33) and reduced nodule diameter (MD -0.43, 95% CI -0.63 to -0.22), with further reductions in free T3 (MD -1.99) and free T4 (MD -3.20) and no significant excess of adverse reactions (RR 0.67, 95% CI 0.36 to 1.22). The authors themselves flag the uncertain quality of the included trials.
Mechanism of Prunella vulgaris L. and luteolin in restoring Tfh/Tfr balance and alleviating oxidative stress in Graves' disease
Experimental work in a Graves' disease model identifying restoration of the follicular helper to follicular regulatory T cell balance, and relief of oxidative stress, as a mechanism by which Prunella vulgaris and its flavone luteolin act on the autoimmune thyroid axis. It supplies a plausible immunological mechanism for the clinical thyroid effects seen in the trial meta-analyses, but is a preclinical study and does not establish a dose for patients.
Prunella vulgaris polysaccharide inhibits herpes simplex virus infection by blocking TLR-mediated NF-κB activation
A hot-water, 30% ethanol-precipitated polysaccharide fraction of Prunella vulgaris inhibited herpes simplex virus in plaque reduction assays. Heparin bead pull-down and immunofluorescence showed the polysaccharide binds viral glycoproteins, and it suppressed viral gene and protein expression together with TLR-driven NF-kB signalling and IL-6 and TNF-alpha induction. This is cell-culture work with an isolated fraction, not evidence that a decoction treats herpes in patients.
The Antitumour Effect of Prunella vulgaris Extract on Thyroid Cancer Cells In Vitro and In Vivo
Prunella vulgaris extract inhibited proliferation and migration of the human thyroid carcinoma lines TPC-1 and SW579 and slowed growth of subcutaneous xenografts, with changes in MKI67, PCNA and CDH1 expression. Cell-line and xenograft evidence only; it does not show that the herb treats thyroid cancer in people, and should not be used to justify substituting it for surgery or radioiodine.
Prunella vulgaris L. active components and their hypoglycemic and antinociceptive effects in alloxan-induced diabetic mice
Fractions of Prunella vulgaris lowered blood glucose and reduced nociceptive responses in alloxan-induced diabetic mice, with the activity tracked to identified constituents. It is the main experimental basis for the theoretical additive effect with hypoglycaemic drugs; there is no equivalent human trial.
⚠ Safety & Contraindications
- Bleeding disorders
Contraindications
Its use is cautious in patients with deficiency or weakness of the spleen and stomach.
Source: Xi S, Gong Y. Essentials of Chinese Materia Medica and Medical Formulas. Academic Press/Elsevier, 2017, pp. 37–43.
Historical Texts
Shen Nong Ben Cao Jing
Eastern Han dynasty, AD 25-220Ben Cao Yan Yi
Song dynasty, AD 960-1279Zheng Lei Ben Cao
Song dynasty, AD 960-1279Ben Cao Gang Mu
Ming dynasty, AD 1578Ben Cao Hui Yan
Ming dynasty, AD 1368-1644Ben Jing Feng Yuan
Qing dynasty, 17th centuryReferences
- Pan J, Wang H, Chen Y. Prunella vulgaris L. – A Review of its Ethnopharmacology, Phytochemistry, Quality Control and Pharmacological Effects . Frontiers in Pharmacology (2022) [DOI]
- Zholdasbayev ME, Atazhanova GA, Musozoda S, Poleszak E. Prunella vulgaris L.: An Updated Overview of Botany, Chemical Composition, Extraction Methods, and Biological Activities . Pharmaceuticals (2023) [DOI]
- Zhang W, Wuhan Q, Na M, Hu R, Mu Q, Bao X. Emerging therapeutic role of Prunella vulgaris in thyroid disease . Chinese Herbal Medicines (2022) [DOI]
- Chen Y, Zhu Z, Guo Q, Zhang L, Zhang X. Variation in concentrations of major bioactive compounds in Prunella vulgaris L. related to plant parts and phenological stages . Biological Research (2012) [DOI]
- Tabba HD, Chang RS, Smith KM. Isolation, purification, and partial characterization of prunellin, an anti-HIV component from aqueous extracts of Prunella vulgaris . Antiviral Research (1989) [DOI]
This information is for educational purposes only and is not intended to replace professional medical advice. Always consult a qualified healthcare provider before using any herbal remedy, especially if you are pregnant, nursing, or taking medications.
📝 Notes
Public notes from the community and your own private notes on Xia Ku Cao.
No notes yet.