Dyer’s woad root (Isatis tinctoria (root))
Synopsis
Dyer’s woad (Isatis tinctoria) is a plant native to Central Asia and southeastern Europe, widely known both as a source of blue dye (indigo) and as a medicinal root in traditional herbal systems—especially in Traditional Chinese Medicine (TCM). The root (Isatidis radix) is the primary medicinal part and is rich in indigo, indirubin, alkaloids, flavonoids, polysaccharides, and glucosinolates, many of which contribute to its strong antiviral, antibacterial, anti-inflammatory, and immune-modulating effects.
Dyer’s woad root is used primarily to:
- Clear heat and resolve toxicity, especially in the context of viral infections, fevers, and sore throats
- Support the immune system, particularly during acute respiratory infections or epidemics
- Treat inflammation of the throat, tonsils, or lymph nodes
- Act against bacterial and viral pathogens, including those responsible for influenza, hepatitis, and herpes
- Inhibit the replication of certain viruses and reduce the severity of viral illness symptoms
- Support detoxification and fever reduction, particularly in the early stages of infection
It is commonly used in TCM as Ban Lan Gen, often in granule or decoction form, alone or in formulas with forsythia (Lian Qiao), honeysuckle (Jin Yin Hua), and scutellaria (Huang Qin). It is included in many "heat-clearing" and "toxin-resolving" remedies for upper respiratory tract infections, sore throat, mumps, measles, and epidemic prevention.
Historical Use
Dyer’s woad root has been used for over 1,000 years in Traditional Chinese Medicine, particularly under the name Ban Lan Gen. It was considered one of the most effective herbs for “cooling the blood, clearing heat, and eliminating toxins,” especially in cases of:
- Swollen throat, tonsillitis, and fever
- Skin eruptions, including rashes or boils linked to internal heat
- Epidemic diseases—TCM texts often described it as protective during plagues and infectious outbreaks
During SARS and COVID-19 outbreaks, Ban Lan Gen gained renewed popularity in China as part of immune-supportive and antiviral herbal protocols. It has been heavily researched in China for its ability to inhibit viral replication, reduce inflammation, and enhance innate immune defenses.
In Western historical use, dyer’s woad was cultivated primarily for its blue dye (indigo precursor) rather than medicinal purposes. However, in recent decades, it has attracted attention in Western herbalism due to its immune and antiviral benefits, especially as herbal interest in TCM antiviral herbs has grown.
Today, dyer’s woad root is frequently found in immune support formulas, cold and flu remedies, and infection-clearing herbal teas, valued for its potency, safety, and deep ethnobotanical legacy.
Body Systems
Immune System (Science)
Liver (Science)
Respiratory System (Science)