Herbs that have Anti-Viral Properties
(We cover Medicinal Herbs first, then Kitchen Herbs. The more technical information is marked in green, so you can skip these parts if you like.)
Both Echinacea purpurea and Echinacea angustifolia have antimicrobial and immune-stimulating properties. They are used for the treatment of viral infections such as influenza, as well as middle ear infections, vaginal candida, and to improve wound healing. A high dose of Echinacea is helpful if you feel susceptible to coming down with something or if you have been exposed to those with infections. (Echinacea is generally not used with auto-immune disorders.)
However, Echinacea is generally considered more effective for infection prevention. A lipophilic extract of Echinacea root rich in alkylamides will prime the immune response before virus exposure, and then sustain it once the virus takes hold.
(In the acute stage of the virus, other antiviral herbs such as Liquorice and sweet wormwood (the latter in pulsed doses), and other immune herbs such as Andrographis and holy basil, become more important.)
Astragalus membranaceus increases white blood cell counts and interferon, thereby increasing the body’s resistance to disease. It is best taken long-term to enhance immune functions, and is especially effective for those with a history of recurring respiratory infections, anaemia, or chronic fatigue syndrome.
Astragalus is contraindicated in progressed Lyme disease.
In Chinese herbal medicine, Astragalus is generally contraindicated in acute infections, except where there is energy deficiency. It has been used in herbal formulations to treat recent viral epidemics, but is more often included in preventative formulations. As per the Chinese herbal medicine guidelines, Astragalus is particularly indicated for prevention when a person has compromised immunity and/or resilience.
Hence, Astragalus can be safely taken for prevention but is best stopped once acute symptoms develop (unless there is advice to the contrary from a skilled Chinese herbal practitioner).
However, once the infection is over, it is very helpful for recovery from any after-effects, such as post-viral fatigue.
Andrographis paniculata has extensive evidence in reducing the incidence, severity and duration of acute respiratory infections (as evidenced by positive results in a meta-analysis, which included 33 studies). It has been shown to stimulate both the antigen-specific and non-specific immune response, as well as increase NK cell activity, antibody-dependent cellular cytotoxicity and antibody-dependent complement-mediated cytotoxicity, thereby supporting host immune defences.
This herb is an immune stimulant and has antiviral properties. It is primarily used as a cough or cold remedy, as it helps to break a fever, ease flu symptoms, and clear congestion.
The use of the black elderberry (Sambucus nigra) during acute respiratory viral infections is relatively new, arising from research conducted in the 1970s. Initial investigations revealed antiviral activity, and this remains a research focus. However, later research has indicated a role for the herb in enhancing immune responses, especially cytokine production. (Elderberry increases the production of inflammatory cytokines IL-1beta, TNF-alpha, IL-6 and IL-8.) Meta-analysis certainly supports its benefit when administered during acute viral infections.
A clinical trial in 473 patients (including many with confirmed influenza A and/or B) found that a combination of elderberry and Echinacea given as soon as possible for 10 days after symptoms developed was as effective as the antiviral drug oseltamivir. There was no suggestion of harmful effects or induction of cytokine storm (the authors used the term septic shock to flag this possibility). In fact, adverse events were higher in the antiviral drug group.
In another large trial involving 312 economy class passengers traveling from Australia to an overseas destination, participants took elderberry continuously from 10 days before flying overseas until five days after arriving at the travel destination. Most cold episodes occurred in the placebo group (17 versus 12), however the difference was not significant (p = 0.4). Placebo group participants had a significantly longer duration of cold episode days (117 vs. 57, p = 0.02) and the average symptom score over these days was also significantly higher (583 vs. 247, p = 0.05). These data suggest a significant reduction of cold duration and severity in air travelers. The herbal treatment was well tolerated, with no serious adverse events.
Medicinal mushrooms can boost immunity by providing polysaccharides- complex sugars that stimulate an immune response. They are very beneficial as preventatives during cold and flu seasons and are also useful when actively fighting an infection.
Shiitake Mushroom – Lentinus edodes. Shiitake is highly prized as food and medicine. It is especially high in zinc and contains several types of polysaccharides that stimulate white blood cell activity and moderate immune function. It has antiviral and antibacterial properties and is showing promise as an anti-tumour medicine. It also helps to protect the liver and lower cholesterol.
Both shiitake and reishi mushrooms activate the innate immune system, triggering the production of NK cells, lymphocytes, neutrophils, macrophages, and inflammatory cytokines.
Reishi – Ganoderma spp. Reishi has been used in China and Japan for over 4,000 years, and is called ‘the immortality mushroom’.
It enhances and controls immune cell functions, and is effective against a very broad range of pathogens; amongst other properties, it is antibacterial, antiviral, and antifungal. (As it moderates the immune system, allergy sufferers may find reishi helpful in reducing inflammation and over-sensitivity. It is often valuable for those undergoing cancer treatment, as it helps protect the body from radiation damage, lessens pain, and improves appetite. Reishi is also an adaptogen, and so helps mitigate the physical and mental impact of the stress response.)
Reishi has been shown to bind to cell surface receptors of immune cells, leading to alteration in the activities of macrophages, T helper cells and natural killer (NK) cells, activate peripheral blood mononuclear cells, promote lymphocyte proliferation and differentiation, and inhibit viral replication.
However, as with Astragalus, the main role of medicinal mushrooms is for infection prevention and they can be discontinued during acute infection onset to make way for other higher priority herbs.
Research suggests that the branched chain beta-glucan polymers found in the fruiting bodies of various mushroom species seem particularly adapted to heightening immune vigilance against potential pathogens. Interaction of mushroom beta-glucans with dectin-1 receptors may even be able to “train” the innate immune response. Trained (innate) immunity (TI) can be induced by a variety of stimuli, of which BCG (Bacillus Calmette–Guérin vaccine) and beta-glucan have been particularly studied. Both BCG (via NOD2 signalling) and beta-glucan (via dectin-1) can induce epigenetic changes that lead to TI. Interestingly, because of the discovery of TI, BCG is currently being investigated as a prevention for acute respiratory viral infection amongst 4,000 healthcare workers.
The inner bark of Tabebuia impetiginosa, an Amazonian tree, can be used to treat colds, influenza, herpes and viral stomatitis (mouth sores, such as a cold sore). It contains quinoids that inhibit virus replication by damaging the DNA and RNA inside the viral protein that would normally insert itself in a healthy human cell and replicate.
St John’s Wort
Hypericum perforatum is well-known for its ability to help mild depression and neuralgia, but it also has potent antiviral chemicals called hypercin and pseudohypericin that proactively fight off viruses. In particular, it is especially useful against viruses that masquerade as human cells, such as Herpes, HIV and Hepatitis C.
(St John’s Wort is of particular interest at present, as it is considered to be effective against ‘enveloped’ viruses, and COVID-19 is an enveloped virus. However, there is as yet no firm evidence that St John’s Wort is effective against COVID-19.)
Althaea officinalis; the herbal extract of the marshmallow plant soothes irritated respiratory tissue and builds immune function.
Herbs and Fever Management
(Patients with COVID-19 infection requiring intensive care unit (ICU) admission have shown higher concentrations of granulocyte colony-stimulating factor (GCSF), IP10, MCP1, MIP1-alpha, and tumour necrosis factor-alpha (TNFalpha) than patients that have not required ICU admission, suggesting that a cytokine storm may be associated with the disease severity.)
One important area of herbs for managing viral infections is the role of diaphoretic herbs in stage II. Their appropriate use could prove to be critical in preventing the development of a cytokine storm.
A diaphoretic is an agent that literally is used to promote sweating, and in the context of a fever, diaphoretic herbs were used to manage the febrile phase of an infection. In modern herbal practice, diaphoretic herbs are still considered appropriate in fever management, including remedies such as Mentha x piperita (peppermint), Achillea (yarrow), Sambucus (elderflower), Matricaria (chamomile), Tilia (lime flowers) and Asclepias tuberosa (pleurisy root). Their objective is to help to facilitate the fever as a “slow burn” (usually the range 100–102°F or 37.8–38.9°C), ensuring that this important physiological response is supported, but kept at a level that is comfortable, restorative and not harmful to the person.
They work best when taken hot, as in an infusion or decoction.
Liquorice – Glycyrrhiza glabra. The herb (not the sweet) contains a substance called glycyrrhizin that reduces the replication of viruses and halts their ability to penetrate replicate inside healthy cells. It has been noted to be effective in the treatment of many viral illnesses, including HIV strains and viral hepatitis. Liquorice is soothing for sore throats and dry coughs. It helps heal irritated tissues, and reduces inflammation and coughing (anti-tussive).
However, Liquorice is not advised if you have high blood pressure or during pregnancy.
In the classical model of pathogenesis, induction of fever is mediated by the release of pyrogenic cytokines such as Tumor Necrosis Factor (TNF), interleukin (IL)-1, IL-6, and interferons into the bloodstream in response to exogenous pyrogens from infecting agents. These are the same cytokines that are largely responsible for cytokine storm. Hence, diaphoretic herbs might well reduce the risk of developing cytokine storm during an infection.
This might be disregarded as idle speculation, except for the eclectic experience with diaphoretic herbs during the Spanish flu pandemic, where they were regarded as key remedies. Drawing from just one of the many testaments to the value of diaphoretic herbs from that time, as reviewed by Abascal and Yarnell: “One physician, who saw 10–35 patients with influenza per day during the epidemic began treatment by mixing 2 teaspoons of boneset and 1 teaspoon of pleurisy root tinctures in a cup of hot water. This was given immediately with a second dose 15 minutes later, a third dose half an hour later, and a fourth dose an hour after the first dose. He reported that this treatment typically reduced a fever of 103–104ºF by 3–4º in a few hours. Yet another physician reported that boneset was always a significant remedy in influenza.”
(We now know that boneset contains low levels of pyrrolizidine alkaloids, so other diaphoretic herbs should be used instead.)
These herbs will support a focussed initial immune response, including enhanced cytokine signalling, and thereby reduce the risk of any infection progressing to the stage III development of cytokine storm.
Herbs are best given in combination, and informed use of herbal prescribing can improve clinical outcomes. In the context of reducing the risk of cytokine storm after an infection has taken hold, the valuable role for the inclusion of diaphoretic herbs in the treatment protocol needs to be given due attention.
Some common kitchen herbs are helpful to build your immunity and ward off respiratory illnesses.
Garlic – Allium sativum. Garlic is anti-viral, anti-bacterial and anti-fungal. The compounds allicin and alliion are responsible for all of these actions, and garlic also has antimicrobial properties.
Ginger – Zingiber officinale. Ginger is very heating and is a diaphoretic, so is excellent for the early stages of a ‘cold’ (viral) type of infection, with symptoms such as feeling cold, sneezing, nasal congestion with white phlegm or a runny nose with clear phlegm, and little or no fever. It may also include muscle stiffness or aches, or a cough with clear or white phlegm. (Do not use ginger for a ‘hot’ or bacterial infections, which involve feeling hotter, a sore throat, or yellow or green phlegm.)
Ginger contains anti-inflammatory compounds, helps to expel mucus, and can ease coughs and deep-seated respiratory congestion including bronchitis.
The best way to use ginger is to chop the root up, boil it, and drink the liquid as a tea. You will usually need to dilute it, and can add a little honey if you wish. Drink frequently until your symptoms have gone.
Peppermint – Mentha × piperita. Peppermint is also a diaphoretic but is very cooling, so is used for the early stages of a ‘hot’ (bacterial) type of infection, with symptoms such as feeling hot or having a fever, sore throat, and yellow or green phlegm. Use it as a tea and drink frequently.
Onions – Allium spp. A centuries-old remedy for breaking up lung congestion is to sauté onions in a little olive oil, placed them on a cloth, apply to the chest while still warm, and let it sit for about half an hour. The aromatics in raw onions can also help calm a cough.
Green Tea – Camellia sinensis. Green tea contains a group of flavonoids called catechins, which appear to inhibit viral infections by blocking the enzymes that allow it to reproduce. Green tea has been known to be effective in inhibiting HIV, herpes simples and the hepatitis B virus. For best effect, gargle with the tea then swallow it.
Olive Leaf – Olea europea. The leaves of Olive trees contain a substance called elenoic acid, and calcium elonate has been identified as a powerful inhibitor of a wide range of viruses in laboratory tests, including influenza, herpes, polio and coxsackie viruses. These substances block the production of enzymes that allow viruses to replicate.
Horseradish – Armoracia rusticana. Horseradish has strong decongestant and antimicrobial properties. After grating the roots, put them into vinegar or honey immediately to prevent the loss of the effective compounds. (Wasabi in Japanese restaurants is usually made from Horseradish.)
The information contained in this article is meant for general use only, and must not be used to replace medical advice or treatment. In particular, if you have any possible COVID-19 symptoms, such as sore throat, fever or shortness of breath, you must seek immediate guidance from a medical professional or call the Coronavirus Health Information Line for advice (ph. 131 450).
When prescribed by a qualified professional, medicinal herbs can be effective for a wide range of viral and bacterial infections. Naturopaths undergo years of training in the use of herbal formulas, and an experienced naturopath can prescribe a powerful combination of herbs tailored to your specific needs. (Only the highest quality medicinal herbs are used at our clinic.)
You may also be interested in reading our article on Improving Your Immune System.
We are currently running a special offer of a 15 minute consult with our naturopath for only $15. These can be carried out in person or by Skype or Facetime. Please give us a call if you would like to book in for one, or you can book online.
 Mehta P, McAuley DF, Brown M, Sanchez E, Tattersall RS, Manson JJ, et al. COVID-19: consider cytokine storm syndromes and immunosuppression. Lancet [Internet]. 2020 Mar 16 [cited 2020 Mar 17]. doi:https://doi.org/10.1016/S0140-6736(20)30628-0. Available from: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)30628-0/fulltext#articleInformation.