With the coronavirus (SARS-CoV-2) making all the headlines, many people are wondering about antiviral herbs.
In this article I will describe antiviral herbs and address how they work.
How Do Antiviral Herbs Work?
When we hear the term antiviral, it’s easy to jump to the conclusion that they work just like pharmaceutical antibiotic drugs. In other words, if you have an infection, then you take something to kill the pathogens.
But herbal antivirals don’t work that way. In fact, they simply can’t work like pharmaceuticals.
Let’s take a step back to see the difference between a bacterium and a virus. Bacteria are living organisms that come in a variety of shapes and have a cell wall. Bacteria live in close association with plants and animals. Virtually all animal life on earth is dependent on bacteria, as they synthesize vitamin B12 into the food chain. As you know, we also have billions of beneficial bacteria living in our guts! However, some bacteria can cause infectious diseases, which can be controlled with antibiotics or antimicrobial herbs.
Viruses, however, are on the edge of life. They don’t have a cell wall and are not able to reproduce on their own, thus they need a host cell in order to replicate themselves. When you have a viral infection, the viruses have invaded your cells. Controlling a viral infection is problematic because the virus is replicating from inside your own cells.
Instead of killing viral cells, what herbal antivirals can do is inhibit the virus from attaching to your cell walls or inhibit the replication of the virus once it gets into your cells. This herbal help can then give your immune system the upper hand to clean up the rest of the infection.
How Do We Know if an Herb is Antiviral?
In times past, we didn’t have the microscopic means to differentiate between the causes of various illnesses. Something that was caused by a virus wasn’t necessarily differentiated from something caused by bacteria. With the current microscopic and genetic analysis tools of researchers, we have a lot of knowledge about the many types of pathogens that can cause infections.
Nevertheless, we have traditional uses of herbs and the combined experience of herbalists from the distant past to the present to support the use of a number of herbs in viral infections. For example, herbalists everywhere would probably agree that elderflower is helpful for supporting a body with influenza accompanied by fever.
One modern way of establishing whether an herb is antiviral is to test it against viral cells in a laboratory. These tests are called “in vitro,” meaning not in a living body. Using a variety of methods, researchers introduce herbal extracts to viruses in a culture dish and then analyze the results. This kind of research can show us some of the ways that herbs work.
In vitro studies or studies using isolated plant constituents aren’t inherently bad. The problem arises when we use those studies to jump to conclusions that aren’t supported by the research. For example, if there is an in vitro study using an isolated extract of a plant that shows promising results, it’s misleading to turn around and claim that the whole herb will have the same results when used in a human. There are a lot of reasons why we might not be able to get the herb at a high enough concentration in the human body to have the desired effects, including rapid processing by the body, potential toxicity of high doses of the herb, or simply that you just can’t get enough herb into the person to have the desired effect.
In summary, when you see claims about an herb’s antiviral activity, here are some ways to critically assess that information:
- What is the basis for the antiviral claim? (Traditional use? Modern-day use? Research?)
- Was there a study of some kind? Was it an in vitro study, a study in animals, or a human clinical trial?
- What part of the herb was used? What preparation of the herb was used? (Note: Isolated constituents, toxic methanol extracts, or essential oils are often used in these trials. These preparations are not whole herbs and are often unsafe or impossible to make at home.)
Sometimes in vitro studies confirm what we already know about an herb because of our experience. For example, I knew that St. John’s wort (Hypericum perforatum) inhibited herpes simplex virus (HSV) long before I knew of any studies supporting that action. Once I saw those studies, it simply confirmed what I already knew from experience. While it is important to recognize what science can teach us, it isn’t the only way we know about herbs.
In addition to in vitro trials, there are in vivo (in a living being) human clinical trials evaluating the effectiveness of herbs in regards to viral infections. There also are in vivo animal studies, but because these are often unethical, I do not cite them in my articles.
Here is a summary of an in vivo human trial. This study followed 312 airline passengers flying overseas from Australia. Half were given an elderberry (Sambucus nigra) preparation and the other half got a placebo (harmless fake medicine). Those taking the placebo had slightly more occurrences of colds or influenza during their trip than did those taking the elderberry. More significantly, those taking the elderberry who did get a cold reported a marked reduction of cold duration and severity compared with those taking the placebo.1
Herbs Go Beyond Being Antiviral
As is often the case, herbs rarely do just one thing. Some herbs that have antiviral activity can also modulate or boost the immune system. That’s really cool! Because really, when we talk about any type of infection, it’s your immune system that is the biggest and baddest player on the field and you want to support it and rely on it as much as you can.
Using herbs to ward off a viral attack is just one way to use herbs for a viral infection. There are many other ways we can give the immune system a helping hand in its endeavors.
When it comes to upper respiratory infections, we can think of using herbs in several ways:
Many herbs can modulate or strengthen the immune system. When taken before an illness (or sometimes at the start of an illness) these immune-modulating herbs can shorten the duration of an illness or stop it entirely.
Most of us would agree that not getting sick in the first place is the best choice! That’s why herbalists love to spend a lot of time promoting herbs that build and nourish the immune system, like astragalus (Astragalus spp.) and medicinal mushrooms. Many herbalists’ experiences show that nourishing the immune system can help to stave off illness, and this is especially helpful for people who are overworked or stressed on a regular basis.
2. Treatment: Support Healing and Address Symptoms
Many over-the-counter drugs for colds and influenza are aimed at stopping any and all symptoms, often by inhibiting your body’s natural defenses. Symptoms are the body’s response to the viral pathogen – stopping symptoms like this can often reduce our ability to heal.
For example, if you have a lot of congestion, you can take a decongestant that will dry you out. This is problematic because mucus is a valuable part of the immune system, acting to envelop and flush pathogens out of the body.
Or if you have a fever, you might take aspirin or a similar drug to artificially lower your fever. This is often counterproductive because the fever is your body’s attempt to rid your body of the invading pathogens, which are sensitive to high temperatures.
Or if you have a cough, you could take a cough-suppressant medicine. You can probably guess that this might be a bad idea, to keep all of that mucus in your throat and lungs, and might even lead to deeper problems like lingering cough, bronchitis, or pneumonia.
The bottom line is, unless symptoms are severe, we don’t want to stop those important processes.
Herbs especially excel when they are used to support your immune system, rather than trying to stop it. With herbs, you can get some symptomatic relief while also supporting healing and shortening the duration of your illness.
For example, if you have a lot of thick, stuck congestion, you can take herbs that thin the mucus and help you dispel it. The result is that you don’t overly dry your mucous membranes and you support your body’s natural defenses (the mucus) while also helping your body expel the gunk (technical term!).
If you have a fever where you feel cold and chilled, you can take herbs to warm up your body and support a healthy resolution of the fever process. If you have a fever where you feel hot and restless, you can take herbs that help you to naturally relax, release heat, and resolve the discomfort.
When herbs are used in this way, they aren’t necessarily “antiviral” as much as they are profoundly supportive of your body’s natural responses to a viral infection. My friend and fellow herbalist jim mcdonald calls these types of herbs “indirect antiviral herbs.” While these herbal allies don’t work directly on the virus, they do support our body’s defenses against the pathogen.
I’ve recently heard numerous people say that we can’t yet claim herbs are effective against the coronavirus. As of this moment, it’s true there haven’t been studies showing direct antiviral activity between any herb and this particular virus (hopefully we will have those soon). However, herbs can absolutely be used for broad support during a viral infection, even without them being directly antiviral. (See below for a classic herbal formula to support a healthy immune response to a viral infection.)
I often see a critical piece missing when people are using herbs to address an upper respiratory infection: recovery. Because the virus takes over and destroys many of your cells in its effort to replicate, viral infections are tough on the body and can leave you feeling worn out, worn down, and deeply tired. In our rush to get back to work and responsibilities, it’s easy to ignore the recovery phase. However, in my experience, this can lead to further illness or an even longer recovery time.
Rest and simple nutrient-dense foods are obviously important for recovery. Herbs can also play a supporting role.
For example, our lungs often feel the effects of a virus long after other symptoms have abated. Using herbs to strengthen and restore lung health can shorten that recovery process. I often get a lingering dry cough after an upper respiratory infection; using demulcent herbs to soothe my mucous membranes is my favorite way to quell that irritation. It works so well that I often wonder what people do without herbs!
A Time-Honored Western Herbal Formula for Viruses
In light of this discussion about using herbs for colds, influenza, and other viral infections, I am sharing a recipe from Emily Han’s and my new book, Wild Remedies: How to Forage Healing Foods and Craft Your Own Herbal Medicine.
This recipe is our version of a very old western herbal formula that has most likely been used for hundreds or thousands of years. It is one of my most-recommended herbal teas for symptoms of an upper respiratory viral infection. I’ve seen it stop a cold or influenza from coming on and I’ve heard from many people who were amazed at how much better it made them feel while they were sick.
Before we get to the recipe, let’s look at the ingredients:
Elderflower (Sambucus nigra, S. nigra ssp. canadensis, S. nigra ssp. caerulea)
Elderflower is one of our best herbal medicines for supporting a healthy fever process, especially when someone is hot, restless, and not sweating. Elderflower relaxes and opens the capillaries and allows for heat to escape. Elderflower is also commonly taken at the onset of an illness to shorten the duration. Herbalist Maude Grieve wrote in the 1930s that elderflowers are an “almost infallible cure for an attack of influenza in its first stage.”2
To confirm the long tradition and experience of herbalists, an in vitro study shows that elderflowers contain immune-modulating constituents.3
There have been recent concerns about elderberries and their connection to worsening viral symptoms and possibly creating cytokine storms. However, there is no scientific evidence, or even case studies, showing that elderberries promote cytokine storms. I’m not concerned about the use of elderberries or elderflowers at this time.
Yarrow (Achillea millefolium)
Taken as a hot tea, yarrow can make you sweat. It promotes circulation to the periphery, dilating capillaries and letting heat escape through the skin. Used in this way, it can be a powerful treatment supporting the fever process when someone is hot, restless, and not sweating. Yarrow is very similar to elderflower in this action, but based on their taste and my experience, it feels like they work in different ways. jim mcdonald says he thinks of yarrow as more of a stimulating diaphoretic, helping to actively push the circulation to the exterior to clear the heat.
From modern science, in vitro studies show that yarrow may also have the ability to inhibit viral replication.4
Note: Yarrow is not recommended during pregnancy.
Rose Hip (Rosa spp.)
While fresh rose hips are famous for being high in vitamin C, dried rose hips are also filled with antioxidants that help to modulate inflammation. The soothing demulcent qualities of rose hips can also soothe an irritated and dry throat. Plus, they taste really good!
Mint (any aromatic mint)
Mint tea brings welcome relief to the symptoms of colds and influenza. Hot mint tea can support a healthy fever process while also relieving tension and mild aches and pains and supporting the digestion during the viral infection. In the following recipe it also helps to improve the flavor of the tea.
Yarrow and Elderflower Tea
This is our version of a very old western herbal formula for colds and influenza. It’s effective for relieving general discomfort, but gentle enough for most people and even children. Both elderflowers and yarrow are relaxing diaphoretics, making this blend especially well-suited to people with fevers who feel hot and restless. For best results, sip this warm tea frequently over the course of an hour or so, rather than all at once. Putting it in a small thermos will keep it warm.
Peppermint (Mentha x piperita), spearmint (Mentha spicata), lemon balm (Melissa officinalis), or even bee balm (Monarda fistulosa or M. punctata) are wonderful mint family members to use in this blend. This is a strong-tasting tea. If you have a sensitive palate, you might want to start with less yarrow or steep it for less time.
What you’ll need…
- 1/4 cup dried yarrow leaves and flowers
- 1/4 cup dried elderflowers
- 2 tablespoons dried rose hips, cut and sifted, or 1/4 cup dried whole rose hips
- Big pinch of dried mint, any type
- 2 cups water
- Honey, to taste (optional)
- Place all of the herbs in a pint jar.
- Bring 2 cups of water to a boil. Pour the water over the herbs, cover, and let steep for 30 minutes.
- Strain. Add honey to taste, if desired. Sip while warm.
Yield: 2 cups
Recipe and recipe photo from Wild Remedies: How to Forage Healing Foods and Craft Your Own Herbal Medicine by Rosalee de la Forêt and Emily Han (Hay House, 2020)
Now I’d love to hear from you!
What are your favorite ways to enjoy yarrow or elderflower?
Were you surprised to learn anything about antiviral herbs or about using herbs for prevention, treatment, or recovery?
Please share in the comments below.
- Evelin Tiralongo, Shirley S. Wee, and Rodney A. Lea, “Elderberry Supplementation Reduces Cold Duration and Symptoms in Air-Travellers: A Randomized, Double-Blind Placebo-Controlled Clinical Trial,” Nutrients 8, no. 4 (2016), doi:10.3390/nu8040182. ↩
- Grieve M. A Modern Herbal: The Medicinal, Culinary, Cosmetic and Economic Properties, Cultivation and Folk-Lore of Herbs. New York, NY: Harcourt Brace & Company, 1931. ↩
- Ho, Giang Thanh Thi, Yuan-Feng Zou, Helle Wangensteen, and Hilde Barsett. “RG-I Regions from Elderflower Pectins Substituted on GalA Are Strong Immunomodulators.” International Journal of Biological Macromolecules 92 (November 2016): 731–38. https://doi.org/10.1016/j.ijbiomac.2016.07.090. ↩
- Pietruszewska, Wioletta, Magda Barańska, and Jakub Wielgat. “Place of Phytotherapy in the Treatment of Acute Infections of Upper Respiratory Tract and Upper Gastrointestinal Tract.” Otolaryngologia Polska = The Polish Otolaryngology 72, no. 4 (August 31, 2018): 42–50. https://doi.org/10.5604/01.3001.0012.2833. ↩