By Juliet Blankespoor and Meghan Gemma
Photography by Juliet Blankespoor
When it comes to fighting infections and warding off looming illnesses, antimicrobial herbs will be among your very best helpers. These remedies contain compounds that directly deter pathogenic bacteria, fungi, viruses, and protozoans.
You’ll find that antimicrobial herbs are valuable remedies for the common cold, the flu, and manageable mild to moderate infections. Depending on the type of infection, antimicrobial herbs are applied topically or taken internally, and in some cases, both applications are beneficial. I keep a reserve of these herbs in my apothecary throughout the year, but I take special care to stock up in preparation for the arrival of cold and flu season.
It’s typically helpful to combine herbal antimicrobials with herbal immunostimulants, which are used on a short-term basis to boost immunity during the initial stages of an infection, as well as throughout the duration of an infectious illness. Classic immunostimulating herbs include echinacea, garlic, and spilanthes. You can read more about how to use them in our article, Herbs for the Immune System.
It’s important to realize that herbs aren’t always the only support you might need to combat infections. Antibiotics and conventional medical care have their place, especially with young children and serious infections. For a list of warning signs that indicate the need for medical care, please visit the article above.
Note that this article is introductory in scope and doesn’t fully cover each medicinal. If you plan to forage any of these herbs (with the exception of goldenseal and white sage, which are threatened and should not be gathered from the wild) you’ll need to seek out identification tips. You’ll also need to learn foraging ethics and guidance before you harvest any plant from the wild! There are deadly poisonous plants out there, so proper identification is paramount.
See our articles on Foraging and Wildcrafting on the blog for more guidance. This is just the tip of the antimicrobial iceberg—for a longer list of antimicrobials, please visit our Herbs for the Immune System.
1. Japanese Honeysuckle (Lonicera japonica, Caprifoliaceae)
Parts Used: Floral buds, opened flowers, stems, and leaves
Preparations: Tincture, decoction, infusion, honey, syrup, poultice, douche, and compress
- Anticatarrhal (decongestant)
I would venture that many of you are intimately acquainted with the blooms of this familiar vine and have partaken of her nectar, sipped straight from the flower’s slender golden tube. All you sucklers will be happy to know that the familiar honeysuckle vine is also a potent medicinal, with far-reaching applications.
Japanese honeysuckle flowers are powerfully antimicrobial and are one of the most widely used medicinal herbs in the world. Honeysuckle can be used internally as a tea or tincture and externally as a poultice or wash. The floral buds and opened blooms are immune stimulating, and strongly antibacterial and antiviral. I use the flowers internally to address hot, inflamed conditions—head colds, flu, urinary tract infections, laryngitis, mastitis, sinus and ear infections, and lower respiratory infections.
The flowers can be gathered as buds and as opened blooms, and tinctured fresh in alcohol. Honeysuckle is also effective as a tea; I combine it with mint and lemon balm to mask its slight bitterness.
Many species of honeysuckle have been used medicinally throughout North America, Europe, and Asia. However, their traditional use and the part employed (bark, leaves, flowers, etc.) varies among species; the biochemistry of the genus is also variable. For example, some honeysuckles have poisonous berries, and some have leaves and bark that can cause vomiting and diarrhea.
Subsequently, we can’t make broad speculations about the medicinal qualities of the entire genus. We’re only talking about Japanese honeysuckle in this article—don’t extrapolate the information here to all honeysuckle species.
Japanese honeysuckle is native to eastern Asia. It has spread throughout much of the world and can now be found in South America, North America, Oceania, and Europe. In the United States, it is especially prolific in the Southeast, but it can be found in almost every state, including Hawaii. Do not plant Japanese honeysuckle as it’s seriously invasive. Harvesting it for medicine is one way to slow its spread!
Japanese honeysuckle is a perennial woody vine that twines around its host, reaching 30 feet (9 m) in length. It can be found in thickets, pastures, and young, open forests and along fencerows, roadsides, and the forest’s edge. It is not a shrub, unlike many other honeysuckle species.
The leaves are elliptical to oblong and leathery when mature (they feel thickish); they are opposite. The leaves grow to 1.2–3 inches (3-7.5 cm) long and have ciliate margins (tiny hairs, like cilia, growing from the edge of the leaf). The vine has peeling, brown bark.
Here are some resources to help you properly identify Japanese honeysuckle:
Contraindications: Some species have been used to stimulate the menses and childbirth, so I would avoid the internal use of honeysuckle in pregnancy to be on the safe side. Make sure to only gather this species; other honeysuckles are not necessarily safe or used medicinally in the same fashion. The berries are poisonous.
2. Usnea (Usnea spp., Parmeliaceae)
Parts Used: Whole lichen
- Anticatarrhal (decongestant)
Usnea is an important medicinal to have on hand in the medicine cabinet. Winter is a fine time to gather Usnea, as heavy winds during storms often knock down branches covered with this versatile medicinal. Lichens are symbiotic organisms, consisting of a fungi and algae. Usnea is fairly easy to recognize, with its thin string-like branching pattern. It can be differentiated from similar lichens by pulling one of the "strings" slowly apart and looking for a thin white strand at the core.
Usnea is especially helpful in treating respiratory congestion, as it is drying and anti-inflammatory, in addition to being antimicrobial. I primarily use Usnea in tincture form, and combine it with immune stimulants, for upper and lower respiratory infections. It is also one of my treasured remedies for urinary tract infections, along with corn silk (Zea mays), uva-ursi (Arctostaphylos uva-ursi) and marshmallow root (Althaea officinalis). Most urinary tract infections can be successfully addressed with this protocol, along with unsweetened cranberry juice. Be sure to look out for warning signs of a kidney infection, such as fever, back pain, and persistent urinary symptoms. Kidney infections are best addressed with antibiotics.
Usnea is more effective as a tincture rather than tea when treating infections, as its antimicrobial properties are more alcohol soluble. I tincture dried usnea with organic grain alcohol at 1:4 95%, and fresh usnea at 1:2 95%. I use a glass blender to create an usnea/alcohol slurry.
Contraindications: Usnea should only be used on a short-term basis, and can be very drying to the sinuses.
3. Garden Sage (Salvia officinalis, Lamiaceae) and White Sage (Salvia apiana, Lamiaceae)
Parts Used: Leaves and stems
Preparations: Tea, tincture, honey, gargle, smoke bundle, and steam inhalation
Illustrious for its culinary uses, garden sage is also a versatile medicinal herb. In fact, its name heralds from the Latin salvere, “to save”, referring to its famous reputation as a lifesaving remedy. This mint family herb has been used therapeutically for centuries with far-reaching applications, ranging from soothing sore throats to washing wounds.
White sage’s medicinal uses are very similar to those of its cousin, although the former is more antimicrobial and stimulating than its domestic brethren. I find that a steam inhalation of the leaves helps to break up respiratory congestion in both the lungs and the sinuses. Try combining it with thyme (Thymus vulgaris) and bee balm (Monarda spp.) in the steam pot, along with a few drops of eucalyptus essential oil.
Sage leaves have traditionally been burned after sickness to purify the home. White sage is a sacred herb to many Native American peoples, and its overharvesting by Westerners has resulted in the demise of wild populations.
Because white sage is becoming increasingly rare in its native habitat due to over-gathering, we suggest learning how to cultivate this precious herb. We have a growing guide (plus recipes!) on the blog. Do not gather or purchase wild-harvested white sage.
Contraindications: Sage is a uterine stimulant and should not be used in large doses by pregnant women. In medicinal quantities, it can dry up the breast milk.
4. Bee Balm (Monarda spp., Lamiaceae)
Parts Used: Leaves and flowers
Preparations: Tea, tincture, honey, and steam inhalation
- Anticatarrhal (decongestant)
I try not to play favorites—even with plants—but I must confess that this group of herbs is among my most cherished of botanical sweethearts. Bee balm is a powerful antimicrobial cold and flu remedy (helps to clear the sinuses, break a fever, and overcome infection). It can be taken internally as a tea or tincture and used as a steam inhalation to treat sinus congestion. It’s also a gentle sleep aid, helping to bring rest during the discomfort of illness.
There are over twenty species in the Monarda genus, all of which are native to North America. It is important to use scientific names with this group, as common names are many and often used interchangeably. The species might be called wild bergamot, bee balm, Oswego tea, or horsemint, depending on where you live and whom you are talking with. The name wild bergamot is especially confusing, as bergamot is also applied to the essential oil from the similarly scented Citrus bergamia. It is the citrus oil, and not Monarda, that is used to flavor Earl Grey tea.
The bergamots are some of the showiest medicinals for the garden, with their tousled tops of crimson and lavender. The flowers are edible, adding a vivid zest to any meal. You can use any of the bee balm species in the Monarda genus medicinally.
Contraindications: Do not use in pregnancy, as bee balm is a traditional menstrual stimulant. As with other spicy herbs, bee balm may aggravate heartburn.
5. Goldenseal (Hydrastis canadensis, Ranunculaceae)
Parts Used: Rhizomes, roots, leaves, and stems (the rhizomes and roots are most potent)
Preparations: Infusion (leaves), decoction (rhizome and roots), tincture, gargle, and powder
- Anticatarrhal (decongestant)
Goldenseal’s vivid yellow roots are famous in the Native American pharmacopeia and are among the most purchased herbs in commerce today. Unfortunately, goldenseal is often used incorrectly—at the first sign of a cold or flu. At this stage, goldenseal's drying qualities can actually counteract the beneficial “flushing” efforts of the immune system—think thin mucus and a runny nose.
Goldenseal becomes helpful when the symptoms of a cold or flu move deeper into the body or become more serious; for instance, when a sinus infection develops or when pneumonia becomes a concern.
You’ll want to reach for the goldenseal specifically when thick yellow-green mucus or discharge is present. You can use it as a gargle or take it internally as a tea or tincture.
Goldenseal can be used topically in powder form, or as a compress or wash to treat skin infections.
Please do not gather goldenseal from the wild or purchase wild roots, as they have been heavily overharvested. Grow your own if you can or purchase organically cultivated roots. Take a peek at our Guide to Growing Woodland Medicinals for more information on cultivating goldenseal.
Contraindications: High doses of goldenseal should only be taken for short periods of time (no more than three weeks), as it can cause inflammation and irritation to the mucous membranes and digestive tract. Even in small doses, tonic use can be overly cooling and drying to most constitutions. Other contraindications include high blood pressure, pregnancy (large doses can cause premature contractions), and breastfeeding.
Looking for more blog articles on herbs for the immune system? We’ve compiled our most comprehensive free herbal resources on the subject, and they’re all right here for your convenience.
Meet Our Contributors:
JULIET BLANKESPOOR founded the Chestnut School of Herbal Medicine in 2007 and serves as the school’s primary instructor and Creative Director. She's been a professional plant-human matchmaker for close to three decades. Juliet caught the plant bug when she was nineteen and went on to earn a degree in Botany. She's owned just about every type of herbal business you can imagine: an herbal nursery, a medicinal products business, a clinical practice, and now, an herbal school.
These days, she channels her botanical obsession with her writing and photography in her online programs and here on her personal blog, Castanea. She's writing her first book: Cultivating Medicinal Herbs: Grow, Harvest, and Prepare Handcrafted Remedies from Your Home Garden. Juliet and her houseplants share a home with her family and herb books in Asheville, North Carolina.
MEGHAN GEMMA is one of the Chestnut School’s primary instructors through her written lessons, and is also the principal pollinator of the Chestnut School’s social media community – sharing herbal and wild foods wisdom from the flowery heart of the school to an ever-wider field of friends, gardeners, healers, and plant lovers.
She has been in a steady relationship with the Chestnut School since 2010—as an intern and manager at the Chestnut Herb Nursery; as a plant-smitten student “back in the day” when the school’s programs were taught in the field; and later as a part the school’s woman-powered professional team. Meghan lives in the Ivy Creek watershed, just north of Asheville, North Carolina.
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