It quickly occurred to me that choosing one herb for this kind of topic is difficult and kind of silly.
There are so many herbs which can be used to treat colds & flus. For example, there are a range aromatic, pungent herbs which are used to vent pathogens through the skin in the early stages of a cold or flu infection. These include fresh ginger, fresh mint, scallions - to name a few household varieties - and many more. Then, there are a great variety of herbs which ease cold & flu symptoms depending on how they manifest in an individual: herbs for treating body aches, reducing phlegm congestion, bringing down fever, opening the sinuses, clearing the eyes, stopping cough and on and on.
Not to mention, Chinese herbs are almost never used solo. They are combined into formulas; and the sophisticated herbalist will likely add a few herbs for supporting and strengthening the patient's constitution and immune system to a formula that is primarily aimed at fighting a viral infection. So, the task of choosing one herb is a bit of a challenge.
I decided to focus on a plant commonly known as Isatis or, among western herbalists and botanists, woad. It is the plant from which the dye, indigo, is derived. Two species of this plant are used: Isatis tinctoria and Baphicacanthus cusia. Of these, the latter is more medicinally potent, but Isatis is the more common and recognizable name. The root, known in Chinese as ban lan gen, and the leaf, da qing ye, are commonly used medicinally for their broad-spectrum anti-viral and anti-bacterial properties.
Isatis was historically grown in Asia, and has long been used in Indian Ayurvedic and traditional Chinese medicine. Now, it is also being cultivated in the west.
The plant is a favorite among Chinese herbalists practicing in the west and in Asia, because is one of the strongest, most broad-spectrum anti-viral and anti-bacterial herbs in the Asian pharmacopeia. Isatis leaf and root are widely used in Chinese hospitals and clinics in the treatment of influenza, chickenpox, mumps, hepatitis, and viral skin diseases. It has gained popularity during the big flu epidemics and the SARS outbreak of recent years.
Older texts in the Chinese Medicine canon (i.e. Shang Han Lun or Discussion of Cold-Induced Disorders, written around 220 CE) taught that one should treat early-stage colds & flus with warm, spicy herbs which vent pathogens through the skin. In contrast, the use of isatis, which is very cold and bitter, belongs to a later wave of Chinese Medicine theory, the era of the Warm Disease School (1600s). The Warm Disease theorists recognized the phenomenon of infectious diseases that are contracted via the respiratory tract, and propagated the use of very cold, bitter herbs to stem such infections by draining toxic heat (think mumps, smallpox, etc.). It happens that these herbs are anti-viral and often anti-bacterial and anti-fungal. Isatis, then, belongs in this group of cold, bitter toxic-heat clearing herbs. (See my article on Classical Chinese Perspective on Colds & Flus for more historical information.)
In today's TCM clinic in the U.S., it is common for an herbalist to add a small amount of heat-toxin clearing herb like Isatis to any formula for cold or flu because of the anti-viral qualities of the herb. The other herbs in the formula would vary based on the patient's symptoms, constitution and the stage of the infection. (Two of the cold/flu formulas from the Oakland-based company Health Concerns use isatis extract along with other Chinese herbs and western herbs like echinacea and goldenseal.) A small amount of isatis can also be useful in supporting a patient with a lingering low-grade cold to clear the body of infection and regain full health. Small amounts of isatis are also sometimes used as immune regulators in formulas for patients with chronic viral infections, immune-deficiency or autoimmune conditions. Think HIV/AIDS, hepatitis, MS, lupus, etc.
Interestingly, three different parts or aspects of the Isatis or Baphicacanthus plant are used in Chinese Medicine:
1. the root: ban lan gen (transliterated from Chinese into pinyin);
2. the leaf: da qing ye; and
3. a processed powder derived from the leaf, known as qing dai. (The leaf is soaked in lime water until rotten. The foam which rises to the surface in this process is qing dai. It is used either as indigo dye, or medicinally.)
All are antipyretic and antiseptic and are used (in Chinese Medicine terms) to clear toxic heat, cool the blood and reduce swelling. All were historically perceived to be effective against epidemic infectious diseases. (Qing dai was distributed widely in China as a preventative during the SARS epidemic.)
All three derivatives of the isatis plant are particularly useful in cooling a very sore, swollen throat. They are also useful in cases involving bleeding (gums, nose) or skin rash due to infection. Common traditional uses have included - in concert with other appropriate herbs - mumps, hepatitis, dipththeria, jaundice, erysipelas, cholecystitis, tonsillitis, and febrile convulsions in children.
Needless to say, isatis is useful in cold & flu prevention & treatment, but also has a much wider range of uses for more serious infectious diseases.
Conditions currently treated by ban lan gen or da qing ye in Asia and in the west include:
- common cold
- sore throat
- sinus infections
- hepatitis A, B, C
- lung abscesses
- psoriasis (by external or internal application)
Research published in China's Second Military Medical College in 2000 by a Dr. Li Sheng showed that ban lan gen had direct therapeutic and preventative effects on the Influenza A virus. Other clinical trials conducted in China have shown ban lan gen's effectiveness in strengthening immune response and in countering:
- bacillus (isatis was more effective than penicillin)
- pyloric heliobacterium
- hepatitis B
- viral myocarditis
- pink eye
- chronic pharyngitis
Patients who are weak and suffer from poor digestion due to cold would not want to use isatis in large quantities or over a prolonged period because it is so cold and draining. It should be used in concert with other herbs. Your acupuncturist or TCM herbalist can create a formula that is just right for your unique condition.
Bensky & Gamble. Chinese Herbal Medicine: Materia Medica. Revised Edition. Seattle: Eastland Press, 1986.
2006 lecture by Dr. Robert Johns, OMD, L.Ac., Berkeley.