Isatis Root

Isatis indigotica · Isatis tinctoria · Ban lan gen · Radix isatidis

Snapshot

Indications	Contraindications
Influenza^{1, 2} Radiation-induced mucositis^{3, 4} Acute bacterial conjunctivitis⁵ Bronchitis⁶	Pregnancy or breastfeeding⁷

Isatis root (ban lan gen) comes from Isatis indigotica or Isatis tinctoria, the plants behind indigo dye, and is used in traditional Chinese medicine and Ayurveda, usually in combination formulas⁶. Its immune-stimulating and antiviral activity in laboratory and animal work drives use for colds, influenza, and bronchitis⁶. It is also used for radiation-induced mucositis in head and neck cancer³, and as eyedrops for bacterial conjunctivitis⁵.

Human research is limited to about five small trials, covering conjunctivitis eyedrops, radiation mucositis, rubella, influenza, and skin irritation. A systematic review of cancer-therapy mucositis found Isatis indigotica extract improved lesions³. A 2021 review of medicinal plants against coronaviruses listed Isatis indigotica among plants studied against severe acute respiratory syndrome coronavirus, and no human study has verified a protective effect⁶. Many products listing Isatis Root exist, mostly liquid extracts and capsules in combination formulas; see Form comparison.

Health Canada lists pregnancy and breastfeeding as a contraindication on most licensed products⁷. Health Canada labels ask patients on prescription medications to consult a practitioner, and indirubin activated cytochrome P450 3A4 (CYP3A4) transcription in laboratory work, with clinical relevance unknown^{6, 7}.

Last updated October 17, 2026. Read how we make monographs.

In the full monograph

31 sources, 19 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources