Chinese Skullcap

The medicine is huáng qín (黄芩), the dried root. It is one of the fifty fundamental herbs and among the most often dispensed in Chinese medicine ^{38Reference 38Buhner · 2013Herbal antivirals: Natural remedies for emerging resistant and epidemic viral infections}. It was first recorded in the Shennong Bencao Jing around 200 AD, and its name joins “huang”, yellow, with “qin”, a herb that stops bleeding ^{44Reference 44Wang et al. · 2018ReviewA comprehensive review on phytochemistry, pharmacology, and flavonoid biosynthesis of Scutellaria baicalensisView study →}.

Huang qin is classified as bitter and cold, entering the Lung, Gallbladder, Stomach and Large Intestine channels ^{41,42Reference 41Yang et al. · 2013Introduction to chinese materia medica (3rd ed.). (Pg 96-98)Reference 42Wu · 2005An illustrated Chinese materia medica}. It clears heat and drains fire, drains damp-heat, resolves toxin, stops bleeding and calms a restless fetus ^{37,41,42Reference 37Bone · 2003A clinical guide to blending liquid herbs: Herbal formulations for the individual patientReference 41Yang et al. · 2013Introduction to chinese materia medica (3rd ed.). (Pg 96-98)Reference 42Wu · 2005An illustrated Chinese materia medica}.

It is given for fever and vexing heat, for cough with thick sputum and for pneumonia ^{37,40,41Reference 37Bone · 2003A clinical guide to blending liquid herbs: Herbal formulations for the individual patientReference 40Barnes et al. · 2007Herbal medicines (3rd ed.)Reference 41Yang et al. · 2013Introduction to chinese materia medica (3rd ed.). (Pg 96-98)}. Other uses include nausea, vomiting and coughing of blood; jaundice and viral hepatitis; diarrhoea and dysentery-like illness; painful urination; high blood pressure and high blood lipids; a restless fetus; and carbuncles, dermatitis and allergic conditions ^{37,40,41Reference 37Bone · 2003A clinical guide to blending liquid herbs: Herbal formulations for the individual patientReference 40Barnes et al. · 2007Herbal medicines (3rd ed.)Reference 41Yang et al. · 2013Introduction to chinese materia medica (3rd ed.). (Pg 96-98)}.

Huang qin is a decoction herb and is almost always used in a formula. Because it is cold and draining, it is not used for cold patterns of deficiency ^{42Reference 42Wu · 2005An illustrated Chinese materia medica}.

In Tibet the most common skullcap is Scutellaria barbata. Both the root and the leaves are juiced and applied to wounds, and given for fevers, indigestion and gastric upsets ^{38Reference 38Buhner · 2013Herbal antivirals: Natural remedies for emerging resistant and epidemic viral infections}.

Western herbal medicine uses a different species, the North American Scutellaria lateriflora, and its aerial parts rather than the root.

Native American peoples took the leaves of S. lateriflora for sore eyes, chills, fever, colds, coughs, heart complaints and as a laxative. They used the root as an emmenagogue and abortifacient, an antidiarrhoeal and a nervine, for kidney disorders and colds, and to ward off smallpox ^{38Reference 38Buhner · 2013Herbal antivirals: Natural remedies for emerging resistant and epidemic viral infections}. The leaves were usually taken as a tea, or steamed and eaten as a vegetable ^{38Reference 38Buhner · 2013Herbal antivirals: Natural remedies for emerging resistant and epidemic viral infections}.

Priest and Priest classified skullcap as a diffusive, a stimulating and relaxing vasodilator and a trophorestorative. They indicated it for nervous irritation, nervous exhaustion, weakness after fever, chorea, hysteria, agitation, epileptiform convulsions, insomnia and restless sleep ^{39Reference 39Hoffmann · 2003Medical herbalism: The science and practice of herbal medicine}. Western practice still uses skullcaps chiefly as nervines, and also for convulsions, nervous tension, intermittent fever, neuralgia, insomnia and restlessness ^{38,40Reference 38Buhner · 2013Herbal antivirals: Natural remedies for emerging resistant and epidemic viral infectionsReference 40Barnes et al. · 2007Herbal medicines (3rd ed.)}.

The root flavonoids baicalin, baicalein and wogonin suppress the NF-κB pathway and directly inhibit COX-2, lowering TNF-α, IL-6 and IL-1β. In cultured endothelium and in mice, all three blunted LPS-driven adhesion-molecule expression and leukocyte migration ^{1Reference 1Lee et al. · 2015In vitroAnti-inflammatory effects of baicalin, baicalein, and wogonin in vitro and in vivo — in vitro and animal studyView study →}.

In a randomised, double-blind, placebo-controlled trial, 374 patients with both coronary artery disease and rheumatoid arthritis took 500 mg of baicalin or placebo daily for 12 weeks. Blood lipids and hs-CRP improved in the baicalin group ^{2Reference 2Hang et al. · 2018RCTBaicalin reduces blood lipids and inflammation in patients with coronary artery disease and rheumatoid arthritis — randomised, double-blind, placebo-controlled trialView study →}.

Two randomised osteoarthritis trials of flavocoxid (500 mg twice daily), a fixed blend of skullcap baicalin and Acacia catechins, found it noninferior to naproxen over 4–12 weeks ^{3,4Reference 3Levy et al. · 2010RCTEfficacy and safety of flavocoxid compared with naproxen in osteoarthritis of the knee — randomised controlled trialView study →Reference 4Levy et al. · 2009RCTFlavocoxid is as effective as naproxen for osteoarthritis of the knee — randomised, double-blind pilot studyView study →}. Two randomised pilots of the related UP446 blend reported reduced knee pain compared with placebo ^{5,6Reference 5Arjmandi et al. · 2014RCTA combination of Scutellaria baicalensis and Acacia catechu extracts for short-term relief of knee osteoarthritis — randomised controlled trialView study →Reference 6Sampalis et al. · 2012RCTA randomised, double-blind, placebo- and active-comparator-controlled pilot study of UP446 — randomised controlled trialView study →}.

None of these trials tested the crude root, and the combination products do not separate the skullcap contribution. Flavocoxid has also been linked to rare cases of acute liver injury ^{30,31Reference 30Chalasani et al. · 2012Case reportAcute liver injury due to flavocoxid (Limbrel), a medical food for osteoarthritis — case seriesView study →Reference 31Curtis et al. · 2020ObservationalComparative safety of flavocoxid vs prescription NSAIDs among osteoarthritis patients — observational cohort studyView study →}.

Gap: no trial has tested the whole root for an inflammatory endpoint. The human data come from a single isolated glycoside or from two-herb combinations.

Baikal skullcap root extract and its main flavone baicalein are strong direct radical scavengers. They also activate the Nrf2/HO-1 pathway and suppress pro-oxidant signalling, through the same flavone chemistry behind the anti-inflammatory effect ^{7Reference 7Chmiel et al. · 2023ReviewPromising role of the Scutellaria baicalensis root hydroxyflavone baicalein as an antioxidant — reviewView study →}.

This activity is reproducible across chemical assays and cell models, and it underlies much of the organ protection reported for the liver, brain and blood vessels. Every result is from purified compounds or extracts in vitro and in animals. There is no human antioxidant-biomarker trial ^{7,8Reference 7Chmiel et al. · 2023ReviewPromising role of the Scutellaria baicalensis root hydroxyflavone baicalein as an antioxidant — reviewView study →Reference 8Fang et al. · 2020Systematic reviewBaicalin and its aglycone: a novel approach for treatment of metabolic disorders — systematic reviewView study →}.

In vitro, baicalein and baicalin inhibit the SARS-CoV-2 3C-like protease and RNA-dependent RNA polymerase ^{9,10Reference 9Liu et al. · 2021In vitroScutellaria baicalensis extract and baicalein inhibit replication of SARS-CoV-2 and its 3C-like protease — in vitro studyView study →Reference 10Zandi et al. · 2021In vitroBaicalein and baicalin inhibit SARS-CoV-2 RNA-dependent RNA polymerase — in vitro studyView study →}.

Skullcap extracts and baicalein block influenza by inhibiting viral neuraminidase ^{11Reference 11Hour et al. · 2013In vitroBaicalein and Scutellaria baicalensis extracts inhibit the neuraminidase activity of pandemic 2009 H1N1 and seasonal influenza A viruses — in vitro studyView study →}.

Activity has been shown against respiratory syncytial virus ^{12,13Reference 12Ma et al. · 2002In vitroAntiviral Chinese medicinal herbs against respiratory syncytial virus — in vitro studyView study →Reference 13Qin et al. · 2022In vitroBaicalin induces a potent innate immune response to inhibit respiratory syncytial virus replication — in vitro and mouse studyView study →}, HIV-1 at the viral-entry step ^{14Reference 14Li et al. · 2000In vitroFlavonoid baicalin inhibits HIV-1 infection at the level of viral entry — in vitro studyView study →}, and hepatitis B ^{15Reference 15Fan et al. · 2023In vitroBaicalin inhibits replication of hepatitis B virus by targeting TRIM25 — in vitro studyView study →}.

The mechanisms include direct enzyme inhibition, blocked viral entry and stronger host interferon responses. Baicalein tablets have completed Phase I safety and pharmacokinetic studies ^{16,17Reference 16Li et al. · 2021RCTSafety, tolerability, and pharmacokinetics of oral baicalein tablets in healthy Chinese subjects — randomised, double-blind, placebo-controlled Phase I multiple-ascending-dose studyView study →Reference 17Dong et al. · 2021RCTSafety, tolerability, pharmacokinetics, and food effect of baicalein tablets in healthy Chinese subjects — randomised, double-blind, placebo-controlled Phase I studyView study →}, and a Phase IIa trial in influenza fever was registered in 2019, with no result published ^{46Reference 46ClinicalTrials.gov · 2019RCTA randomized, double-blind, placebo-controlled, multicenter Phase IIa clinical trial of the effectiveness and safety of baicalein tablets in healthy adults with influenza fever (NCT03830684) — trial registration. https://clinicaltrials.gov/study/NCT03830684View study →}.

Gap: all antiviral efficacy data are from cells or animals. The one human programme tests an isolated compound, not the root, and has not reported whether it shortens or prevents infection.

Some of the liver work used the root itself rather than a single molecule. A methanol extract of S. baicalensis root reduced liver fibrosis, lipid peroxidation and hydroxyproline in rats with bile-duct ligation or carbon tetrachloride injury ^{18Reference 18Nan et al. · 2002AnimalScutellaria baicalensis inhibits liver fibrosis induced by bile duct ligation or carbon tetrachloride in rats — animal studyView study →}.

Isolated baicalin reproduces this across models of alcohol-associated liver disease, fatty liver and toxin injury, acting through antioxidant, anti-inflammatory and stellate-cell pathways ^{19,20Reference 19Fang et al. · 2022Baicalin confers hepatoprotective effect against alcohol-associated liver disease by upregulating microRNA-205 — animal studyView study →Reference 20Yang et al. · 2021ReviewPharmacological properties of baicalin on liver diseases — narrative reviewView study →}.

The whole body of work is preclinical.

Gap: no human liver-protection trial exists, and rare liver injury has been reported with a baicalin-containing product ^{30Reference 30Chalasani et al. · 2012Case reportAcute liver injury due to flavocoxid (Limbrel), a medical food for osteoarthritis — case seriesView study →}.

There is a very large in vitro and animal literature. Baicalein, wogonin and oroxylin A induce apoptosis, arrest the cell cycle and inhibit proliferation across leukaemia, breast, colon, lung and cervical cancer lines, largely by suppressing NF-κB and modulating p53 and the tumour microenvironment ^{21,22Reference 21Banik et al. · 2022Systematic reviewWogonin and its analogs for the prevention and treatment of cancer — systematic reviewView study →Reference 22Zieniuk et al. · 2025Systematic reviewThe therapeutic potential of baicalin and baicalein in breast cancer — systematic reviewView study →}.

Two systematic reviews of this preclinical work judge the flavonoids promising but note the near-total absence of clinical data ^{21,22Reference 21Banik et al. · 2022Systematic reviewWogonin and its analogs for the prevention and treatment of cancer — systematic reviewView study →Reference 22Zieniuk et al. · 2025Systematic reviewThe therapeutic potential of baicalin and baicalein in breast cancer — systematic reviewView study →}.

People have been exposed only through multi-herb formulas, such as PHY906 given alongside chemotherapy, and in ex vivo experiments on patient leukocytes. There are no human antitumour efficacy data for the herb or its isolated compounds.

Skullcap flavonoids stabilise mast cells and cut histamine release, suppress IgE-mediated responses, and drive eosinophil apoptosis. Baicalein, wogonin and an ethanol extract reduced airway inflammation in ovalbumin-sensitised mice ^{23Reference 23Bui et al. · 2017Baicalein, wogonin, and Scutellaria baicalensis ethanol extract alleviate ovalbumin-induced allergic airway inflammation — animal studyView study →}, and wogonin induced eosinophil apoptosis while attenuating allergic airway inflammation in a mouse asthma model ^{24Reference 24Lucas et al. · 2015In vitroWogonin induces eosinophil apoptosis and attenuates allergic airway inflammation — in vitro and mouse studyView study →}.

These findings match the herb’s traditional use for allergic complaints. All of them are from cells or mice, and there is no human allergy or asthma trial.

Baicalein is under development as an isolated neuroprotective drug, chiefly for Parkinson’s disease. Two systematic reviews and meta-analyses of animal Parkinson’s models found consistent protection of dopaminergic neurons, attributed to antioxidant, anti-inflammatory and anti-aggregation effects ^{25,26Reference 25Wang et al. · 2020Meta-analysisPreclinical evidence and possible mechanisms of baicalein for rats and mice with Parkinson’s disease — systematic review and meta-analysis of animal modelsView study →Reference 26Zhu et al. · 2019Systematic reviewNeuroprotective effects of baicalein in animal models of Parkinson’s disease — systematic review of experimental studiesView study →}. A preclinical meta-analysis reported antidepressant-like effects of baicalin in rodent models ^{27Reference 27Wang et al. · 2024Meta-analysisThe effects of baicalin in depression: preclinical evidence construction based on meta-analysis of animal studiesView study →}.

Baicalein has completed Phase I pharmacokinetic and safety trials ^{28Reference 28Li et al. · 2014RCTSafety, tolerability, and pharmacokinetics of a single ascending dose of baicalein chewable tablets in healthy subjects — randomised Phase I studyView study →}.

The clinical work is on the purified compound. There are no human neurological efficacy data, and the herb has never been tested for a cognitive or mood endpoint.

Baicalin improves insulin sensitivity and glucose handling in rodent models, in part by activating hepatic carnitine palmitoyltransferase-1 (CPT1) to increase fatty-acid oxidation and reduce diet-induced obesity and fatty liver ^{29Reference 29Dai et al. · 2018Chemoproteomics reveals baicalin activates hepatic CPT1 to ameliorate diet-induced obesity and hepatic steatosis — animal studyView study →}.

A systematic review of preclinical metabolic-disorder studies reaches the same conclusion ^{8Reference 8Fang et al. · 2020Systematic reviewBaicalin and its aglycone: a novel approach for treatment of metabolic disorders — systematic reviewView study →}.

Human data are limited to one small controlled study combining skullcap extract with metformin, which cannot separate the herb from the drug.

Liver. Rare idiosyncratic liver injury has been documented. In a US drug-induced liver injury network case series, four patients developed acute liver injury after taking flavocoxid (Limbrel), a baicalin-containing medical food, and all recovered within 3–12 weeks of stopping it ^{30Reference 30Chalasani et al. · 2012Case reportAcute liver injury due to flavocoxid (Limbrel), a medical food for osteoarthritis — case seriesView study →}. A large claims-based cohort found flavocoxid carried a higher rate of liver injury and hypersensitivity pneumonitis than prescription NSAIDs ^{31Reference 31Curtis et al. · 2020ObservationalComparative safety of flavocoxid vs prescription NSAIDs among osteoarthritis patients — observational cohort studyView study →}.

Drug interactions. In healthy volunteers who took the root extract for 13 days, losartan metabolism (CYP2C9) slowed by about 30% and chlorzoxazone metabolism (CYP2E1) rose by about 40%, while midazolam (CYP3A4) and the other test drugs were not meaningfully changed ^{48Reference 48Yi et al. · 2009Effects of Angelicae tenuissima radix, Angelicae dahuricae radix and Scutellariae radix extracts on cytochrome P450 activities in healthy volunteers — healthy-volunteer studyView study →}.

Isolated baicalin has been tested on its own. Taken daily by healthy men, it sped the breakdown of bupropion by CYP2B6 ^{50Reference 50Fan et al. · 2009Induction of cytochrome P450 2B6 activity by the herbal medicine baicalin as measured by bupropion hydroxylation — healthy-volunteer studyView study →}. Over 14 days it lowered blood levels of rosuvastatin, which is carried into the liver by the OATP1B1 transporter, by up to 47% depending on the volunteer’s transporter genotype ^{34Reference 34Fan et al. · 2008RCTThe effect of herbal medicine baicalin on pharmacokinetics of rosuvastatin, a substrate of OATP1B1 — randomised human studyView study →}. A single 500 mg dose had no clinically relevant effect on ciclosporin ^{49Reference 49Liu et al. · 2019A single dose of baicalin has no clinically significant effect on the pharmacokinetics of cyclosporine A in healthy Chinese volunteers — healthy-volunteer studyView study →}.

In rats, baicalin inhibited CYP3A activity and displaced the CYP3A substrate nifedipine from plasma proteins ^{33Reference 33Cheng et al. · 2014AnimalContribution of baicalin to plasma protein binding displacement and CYP3A inhibition in the pharmacokinetics of nifedipine in rats — animal studyView study →}, an effect not seen in people. Care is still sensible with narrow-therapeutic-index drugs cleared by CYP2C9 or carried by OATP1B1 ^{32Reference 32Zhou et al. · 2021ReviewDrug–herb interactions between Scutellaria baicalensis and pharmaceutical drugs — reviewView study →}.

Bleeding. Skullcap flavonoids act on the COX and LOX pathways of arachidonic acid, so caution with anticoagulant or antiplatelet therapy is reasonable. The interaction has not been studied in people.

Traditional cautions. In Chinese medicine the root is avoided in cold or deficiency patterns ^{42Reference 42Wu · 2005An illustrated Chinese materia medica}.