Herbal traditions have used these plants for centuries, but we like to go a step further and look at what modern research actually shows. Below are nine herbs in our Respiratory Tract, Productive Cough & Asthma blend, along with a plain-language look at the peer-reviewed studies behind each one.
Elder Flower (Sambucus nigra Flos)
A meta-analysis of randomized controlled clinical trials found that elderberry supplementation substantially reduced upper respiratory symptoms including cough, nasal congestion, and sore throat. In laboratory testing, Sambucus nigra extract was shown to inhibit infectious bronchitis virus, a coronavirus, at an early point in the infection process. Elder flowers in particular have long been described in the pharmacological literature as antipyretic, expectorant, anti-inflammatory, and antiviral, distinct from the berries in their traditional respiratory use. 🔗 Meta-analysis (PubMed) · Bronchitis virus study (PubMed) · Phytochemical review (PMC)
Denseflower Mullein (Verbascum densiflorum)
Mullein flowers are recognized in European herbal medicine as a treatment for inflammation, asthma, and spasmodic coughs, and a chemical analysis of Verbascum densiflorum flowers confirmed the presence of flavonoids and phenylethanoids believed responsible for this anti-inflammatory and antimicrobial activity. In classic pharmacological testing, an infusion prepared specifically from the flowers of Verbascum densiflorum (referred to by its synonym V. thapsiforme) reduced the infectious and haemagglutination yields of a range of influenza virus strains in cell culture. Separately, research on the closely related species Verbascum phlomoides confirmed a direct correlation between the polyphenol content of mullein flower extracts and their measurable anti-inflammatory activity. 🔗 Flavonoid characterization study (PubMed) · Antiviral infusion study (PubMed) · Polyphenol/anti-inflammatory study
Mint (Mentha)
Inhaled Mentha piperita (peppermint) essential oil reduced airway inflammation and markers of allergic asthma in a laboratory model exposed to fine particulate matter, working through the IL-6/JAK2/STAT3 signaling pathway. In a separate pharmacological study, peppermint oil produced a dose-dependent relaxation of contracted tracheal tissue, involving prostaglandin and nitric oxide pathways, providing a mechanistic basis for its traditional use in respiratory disease. A comprehensive review of peppermint and its main compound menthol confirmed a range of anti-inflammatory activities relevant to conditions like asthma and other respiratory disorders. 🔗 Asthma model study (PubMed) · Tracheal relaxation study (PubMed) · Comprehensive review (PubMed)
Broad-Leaved Thyme (Thymus pulegioides)
Laboratory testing of Thymus pulegioides essential oil found strong antibacterial activity against Streptococcus pyogenes and Staphylococcus aureus, two bacteria commonly implicated in respiratory tract infections, alongside antioxidant capabilities that outperformed reference compounds. In a separate study, the essential oil showed significant antifungal activity against Candida and Aspergillus species, both of which can affect the respiratory tract, working by damaging the fungal cell membrane. A review of Thymus phenolic-rich extracts identified Thymus pulegioides among the species with the strongest nitric oxide radical-scavenging capacity, supporting its traditional anti-inflammatory use. 🔗 Antimicrobial/antioxidant study (PubMed) · Antifungal study (PubMed) · Anti-inflammatory review (PMC)
Lungwort (Pulmonaria officinalis)
A dedicated chemical and biological analysis of Pulmonaria officinalis ethanolic extract, a plant traditionally used for respiratory ailments, found it to be rich in polyphenols and to have measurable antioxidant activity. A separate in vitro and computational study found that Pulmonaria officinalis extracts helped mitigate oxidative stress induced by peroxynitrite (a reactive molecule linked to lung tissue damage) and showed inhibitory activity against the COX-2 enzyme involved in inflammation. A comprehensive review of lungwort's biological activities described its long traditional use in pulmonary disorders as an expectorant and anti-inflammatory agent, attributing this to its rich profile of over 90 identified phytochemicals. 🔗 Antioxidant study (PMC) · Oxidative stress/COX-2 study (PMC) · Biological activities review
Sage (Salvia officinalis)
A pharmacological study found that Salvia officinalis extract has genuine bronchodilator activity, working through the activation of potassium channels and inhibition of the phosphodiesterase enzyme, providing a sound basis for its traditional use in hyperactive airway disorders such as asthma and cough. In a randomized, double-blind, placebo-controlled clinical trial, a spray containing sage extract significantly reduced throat pain intensity in patients with acute pharyngitis within the first two hours of use. In a separate clinical trial, lozenges combining sage and echinacea extract reduced throat pain by 48% after a single dose and measurably reduced viral load in patients with acute sore throat. 🔗 Bronchodilator mechanism study (PubMed) · Pharyngitis spray trial (PubMed) · Sore throat/viral load trial (PMC)
Common Daisy (Bellis perennis)
Bellis perennis has a documented traditional use for treating infections of the upper respiratory tract, and phytochemical research isolated an active saponin compound from daisy flowers using bioassay-guided fractionation methods. In an antibacterial screening study, extracts of Bellis perennis flowers were shown to be active against Streptococcus pyogenes, Staphylococcus aureus, and Staphylococcus epidermidis, all bacteria associated with throat and respiratory infections. Separately, laboratory testing of daisy's aqueous extract confirmed meaningful antioxidant activity, including strong free-radical scavenging capacity, supporting the plant's traditional anti-inflammatory reputation. 🔗 Phytochemical isolation study (PubMed) · Antibacterial screening study · Antioxidant activity study (PubMed)
Hyssop (Hyssopus officinalis)
In a randomized, triple-blind, placebo-controlled clinical trial, hyssop syrup taken as an add-on to routine asthma treatment produced significant improvement in lung function and asthma control specifically in patients with a productive cough. In an animal model of chronic allergic asthma, Hyssopus officinalis reduced airway inflammation and helped rebalance the immune signaling molecules responsible for driving chronic airway disease. Separately, laboratory testing of hyssop essential oil found significant antifungal activity against multiple clinical strains of Candida, a class of pathogens that can complicate chronic respiratory conditions. 🔗 Asthma clinical trial (PubMed) · Airway inflammation study (PMC) · Antifungal study
Ground-Ivy (Glechoma hederacea)
Laboratory testing of a hot water extract of Glechoma hederacea found it prevented inflammatory cell damage and significantly reduced markers of nitric oxide and oxidative stress in immune cells exposed to a bacterial toxin. A separate study confirmed that supercritical fluid extracts of ground-ivy had meaningful antioxidant, antimicrobial, and antibiofilm properties. Research into ground-ivy's active constituents found that several of its rosmarinic acid-related compounds directly inhibited the NF-κB inflammatory signaling pathway and the COX-2 and iNOS enzymes involved in producing inflammation, supporting its long traditional use for coughs, bronchitis, and colds. 🔗 Antioxidant/anti-inflammatory study (PubMed) · Antimicrobial/antibiofilm study · Anti-inflammatory constituents study (PubMed)
Why This Matters
Each of these herbs has been studied individually for its effects on the airways and respiratory tract — largely in laboratory and animal studies, with an encouraging number of human clinical trials for herbs like hyssop, sage, and elder. We combine them because their documented modes of action work together at different points along the respiratory system: from relaxing constricted airways and thinning mucus, to fighting the bacteria, viruses, and fungi that can complicate a cough, and calming the underlying inflammation behind conditions like asthma and chronic bronchitis.
This post is for educational purposes and summarizes existing scientific literature. It is not medical advice, and our blend is not intended to diagnose, treat, cure, or prevent any disease. Please consult a healthcare provider before using herbal supplements, especially if you have asthma, COPD, or another chronic respiratory condition, or are taking prescribed respiratory medication.