Antimicrobial Plants And Immunomodulators

Herbal tradition includes many infection-fighting plants. Many of these plants are now known to contain various immunomodulating fractions, particularly polysaccharides, as in licorice (Glycyrrhiza glabra) root and the popular echinacea (Echinacea spp.) roots or seed heads. Both plants can be taken as decoctions of the roots, as herbal tinctures or in combination with other herbs in a formula. Licorice is an underutilized herb in viral infections in Western botanical practice especially in children who typically enjoy its taste. Licorice has not been well studied in influenza but drew much attention in the deadly sudden acute respiratory syndrome (SARS) epidemic. An herbal formula containing licorice was dispensed to 3,160 at-risk hospital workers during the epidemic. None of those taking the formula contracted the disease compared to 0.4% among those who did not. Another study looked at the antiviral potential of certain constituents against coronavirus from patients with SARS. Glycyrrhizin from licorice was the most active and successful at inhibiting replication of the virus. Licorice, of course, has a long folk history of use to treat coughs and inflamed throats, providing needed symptom relief in influenza.

Echinacea helps aid recovery from flu and colds in many people. In a mouse model of influenza A infection, an extract known as Esberitox (containing Echinacea purpurea and Echinacea pallida root, Baptisia tinctoria root, and Thuja occidentalis leaf extracts) significantly prolonged survival compared to placebo. Many of the clinical trials involving various Echinacea species and extracts have been in patients with poorly characterized upper-respiratory-tract infections; many of these easily could have been influenza infections. The latest meta-analysis of these clinical trials concludes that whereas Echinacea can reduce the incidence and duration of upper-respiratory-tract infections, no one extract has been conclusively proven to be the best. Most of the trials assessed in this analysis did not include sufficient testing to rule out influenza infection, though influenza pneumonia was definitely not studied. Though valuable by itself, we add Echinacea to formulae containing other herbs with specific history of long use in influenza. Good choices include lomatium (Lomatium dissectum) root, elder (Sambucus nigra) fruit, boneset (Eupatorium perfoliatum) herb, pleurisy root (Asclepias tuberosa) or inmortal (Aslcepias asperula) root, and, perhaps, wild indigo (Baptisia tinctoria) root.

Elder fruit has long been used to treat influenza and clinical trials show that elderberry syrup, a highly palatable remedy, has the ability to reduce the duration and intensity of influenza. Another classic flu remedy is boneset that, while poorly researched, is recommended by past and present herbalists as especially useful in alleviating the myalgia and pain of seasonal influenza. Lomatium is also poorly researched but was widely used by both Native Americans and Mormon settlers in Utah and Oregon for lung problems, difficult fevers, and pneumonia. A Dr. Krebs reported that a decoction of the root was used successfully as a treatment in the 1918 pandemic. However, Dr. Krebs also noted that a decoction would fail to extract the plant’s oils that he considered to be the most active constituents. Lomatium contains many complex constituents and is known to occasionally cause a rash that is deemed not to be allergic in nature. Michael Moore states that the skin reaction can be avoided if lomatium is combined with dandelion root. Pleurisy root, as its name suggests, has a long history of use in various pulmonary afflictions. It was widely used by Eclectic physicians during the 1918 pandemic. Pleurisy root continues to be used for the chest tightness or painful cough of influenza. The root has a diaphoretic action that is useful in fevers. See Tables Doses of Anti-Influenza Herbs and Specific Indications of Herbal Remedies According to Michael Moore and the Eclectics.

Many practitioners also include baptisia as a treatment for influenza, usually as part of the Esberitox formula mentioned above. Interestingly, the use of baptisia in the acute phase of influenza runs counter to the Eclectic tradition in which the herb was saved for more “septic” or congested stages of influenza. Thus, it was used as a treatment for influenza-related pneumonia in the 1918 pandemic. Small studies show that Esberitox safely and effectively reduced the duration of upper-respiratory infections in adults. The formula combined with antibiotics in patients with severe bacterial bronchial infections (a condition that the Eclectics would have considered appropriate for treatment with baptisia) led to a faster recovery than antibiotics alone.

Table Doses of Anti-Influenza Herbs

HerbPart UsedDose
Panax quinquefolius (American ginseng)RootTincture, 2-4 ml three times per day
Panax ginseng (Asian ginseng)RootTincture 2-4 ml three times per day
Taraxacum officinale (dandelion)RootTincture, 3-5ml three times per day; tea, 1 tsp/cup water, sipped 10-15 minutes ac
Glycyrrhiza glabra (licorice)RootTincture, 3-5 ml three times per day
Echinacea spp.Echinacea purpurea, seed head; Echinacea angustifolia, rootTincture, 5 ml every hour for first 48 hours, then 5 ml every 3-4 hours
Lomatium dissectumRootTincture, 1-3 ml three times per day
Sambucus nigra (elder)FruitTincture, 2-5 ml three to four times per day; tea, 1 tsp/cup water, three to four times per day; syrup, 1 tsp four times per day
Eupatorium perfoliatum (boneset)Flowering topsTincture, 1-3 ml three to four times per day
Asclepias tuberosa (pleurisy root)RootTincture, 1-3 ml four times per day
Baptisia tinctoria (wild indigo)RootTincture, 1-2 ml three times per day


Table Specific Indications of Herbal Remedies According to Michael Moore and the Eclectics


SymptomsHerbal Remedies
General remediesAralia racemosa (California spikenard) root, 

Lomatium dissectum root

Hot, dry patients who are not secreting (no sweating, dry cough)Aslcepias asperula (inmortal) root, Aslcepias tuberosa (pleurisy) root, Capsicum spp. (cayenne) fruit with Lobelia inflata (lobelia) flowering tops
Malaise, body achesActaea racemosa (black cohosh) root, Eupatorium perfoliatum (boneset) flowering top
Pleurisy, hacking irritated cough, blood streaks in mucus
With flushed face, sweating, headacheBryonia cretica (bryony) root
With lymphadenopathyPhytolacca americana (poke) root
Wet cough, perspiring, flushed face, acute onset, restlessGelsemium sempervirens (gelsemium) root
Wet cough, dyspneaGrindelia spp. (gumweed) flower bud, Ligusticum ported (osha) root, Prunus virginiana (wild cherry) bark, Verbascum thapsus (mullein) flower
Wet, persistent cough after influenzaEriodictyon angustifolia (yerba santa) leaf