Baical skullcap (Scutellaria baicalensis)

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15. Safety

Adverse effects in trials. Baicalein tablets, 200–600 mg for up to 10 days: 24 adverse events in 17 of 30 healthy volunteers and 1 in 6 on placebo, all mild or moderate and resolved; the eight judged drug-related were raised triglycerides (3), proteinuria (2), raised ALT (1), raised AST (1) and raised hs-CRP (1) [30]. Saffron and Scutellaria trial: 66 adverse events across four arms, 13 possibly related, mainly headache, respiratory infections, sleep disturbance and gastrointestinal upset; three severe events (two on placebo, one on Scutellaria alone) were judged unrelated [31]. The WHO records rare gastrointestinal discomfort and diarrhoea with oral use, and notes that liver damage from the root had been suggested but not linked to any published case (as of 2007) [4].

Liver injury.

LiverTox rates skullcap as likelihood category B, "very likely but rare cause of clinically apparent liver injury", and notes that Chinese skullcap supplements have been followed by acute hepatitis with jaundice 1 to 3 months after starting; many cases involved several botanicals, and some S. lateriflora cases involved germander adulteration or mislabelling [35]. Soldera’s editorial reviews the same field [37]. AIP comment: every case AIP has read involved a baicalin-concentrated product or a multi-ingredient mixture; none involved the root alone. In both rechallenge-positive cases the product given again held other ingredients too (the same four-ingredient joint supplement in Yang 2012; two decoctions sharing four other herbs in Tang 2025), so neither isolates the root. The flavocoxid series, where the shared factor is purified baicalin, points the same way. AIP Medicine position: rare idiosyncratic liver injury from the root’s flavones is possible and plausible, and has not been proven for the root itself. The risk at traditional doses is low and cannot be called zero. Onset has ranged from days to 16 weeks.

Drug-induced pneumonitis. Case reports link interstitial pneumonia and acute respiratory failure to Japanese Kampo formulas containing the root, especially Sho-saiko-to, with baicalin proposed as the cause; risk rose with interferon co-administration, longer use and older age [7]. Braun and Cohen report Makino’s estimate that the implicated formulas (Sho-saiko-to, Oren-ge-doku-to) supply about 319 mg baicalin a day, against 12–27 mg from a tea [7]. A 2–4 g daily dose of root at 10–12 % baicalin supplies about 200–500 mg, the same range as the formulas (AIP arithmetic). A provocation test implicated the root in pneumonitis from a formula that also contained Bupleurum [8]. Sho-saiko-to is contraindicated with interferon therapy [7]. AIP comment: this is a formula-level signal of immunological type; its relevance to the single herb at Western doses is unknown. A new dry cough, breathlessness or fever while taking the root is a reason to stop it and seek prompt medical assessment.

Toxicology. In rabbits a decoction at 10 g/kg by mouth caused sedation without toxicity, while an aqueous extract at 2 g/kg intravenously killed all animals within 8–12 hours (none died at 1 g/kg); the oral LD50 of a 70 % methanol extract in mice exceeded 2 g/kg; dogs given 4–5 g/kg of an aqueous extract three times a day for 8 weeks showed no toxic effects [4]. An aqueous extract gave a negative Ames test at 40 mg/plate; intraperitoneal injection of the extract in mice was reported as mutagenic [4].

Contraindications and cautions.

AIP comment on pregnancy: the teratogenic dose in rats is about 25 g/kg, and the root has a traditional use in threatened miscarriage; the human data are nil. AIP Medicine position: avoid in pregnancy (the first trimester without exception) and in breastfeeding. The traditional use in threatened miscarriage belongs to supervised Chinese-medicine practice, and no human safety data support it.

Herb–drug interactions.

Overdose. No human overdose report was found.

TGA safety information. Database of Adverse Event Notifications (DAEN), medicines, searched in September 2026 for medicines whose name or ingredients contain "baicalensis", reports from 01/01/1971 to September 2026 [47]. Result: 48 reports, 40 with a single suspected medicine, no deaths. Every product named was a multi-ingredient listed or Chinese medicine; none was the single herb. The commonest terms were diarrhoea (8), urticaria (8), nausea (7), anaphylactic reaction (6), vomiting (5) and dyspnoea (5). Most anaphylaxis reports (2008–2010) named one sinus tablet that also contains Andrographis paniculata. No report named pneumonitis or interstitial lung disease. Five reports carried liver terms:

A DAEN entry records a suspicion; the TGA does not confirm the event or its cause, and these reports cannot give a rate. AIP comment: the 2018 report involves the same type of product (Acacia catechu with S. baicalensis for joints) as the flavocoxid series and the Yang 2012 case, and deserves weight for that reason. A search for "scutellaria", which also takes in S. lateriflora products, returned 33 medicines and 134 reports. TGA safety alerts and recalls: the TGA site was searched in September 2026 for "scutellaria", "skullcap", "baical" and "baicalin". It returned no alert, recall or Medicine Safety Update about S. baicalensis. One safety alert (kava, 28/08/2002) mentions skullcap: a kava product labelled as containing S. lateriflora was tested by the TGA, and S. lateriflora was not found in it [48].

Referral line. Anyone who is pregnant, breastfeeding, under 12, taking prescription medicines (in particular losartan, statins, ciclosporin, interferon or anticoagulants), or who has had liver disease or a reaction to a herbal product should consult a degree-qualified herbalist with competencies and adequate training in pharmacognosy before using Baical skullcap root. Jaundice, dark urine, itch or abdominal pain while taking it are reasons to stop at once and seek urgent medical assessment.