Mullein

Whole-plant extracts of mullein inhibit a range of bacteria in the laboratory. A benchmark ethnopharmacology study found water, ethanol and methanol leaf extracts active against Klebsiella pneumoniae, Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli, with the water extract — the closest analogue to a tea — among the more active ^{3Reference 3Turker AU · 2002In vitroBiological activity of common mullein, a medicinal plant — in vitro (antibacterial, antitumor, toxicity)View study →}. Later in vitro work reproduced activity against Gram-positive and Gram-negative strains, and reviews consolidate antibacterial action as the herb’s most repeatedly demonstrated pharmacology ^{1,7Reference 1Turker AU · 2005ReviewCommon mullein (Verbascum thapsus L.): recent advances in research — reviewView study →Reference 7Zhang N et al. · 2023In vitroAntioxidant, AChE inhibitory, and anticancer effects of Verbascum thapsus extract — in vitroView study →}. The recurring interest in mullein against Mycobacterium (the plant’s folk names historically link it to tuberculosis) remains a historical and mechanistic hypothesis rather than a demonstrated cure ^{12Reference 12McCarthy E · 2011ReviewWhat’s in a name? Can mullein weed beat TB where modern drugs are failing? — reviewView study →}. All of this is in vitro; no clinical infection trial exists.

Gap: No human data, and minimum-inhibitory concentrations vary widely with extract solvent and plant part, so a real-world dose is undefined.

Mullein extracts consistently scavenge free radicals in standard chemical assays. Methanol leaf extract shows measurable DPPH and ABTS radical-scavenging activity alongside a characterised phenolic profile ^{7Reference 7Zhang N et al. · 2023In vitroAntioxidant, AChE inhibitory, and anticancer effects of Verbascum thapsus extract — in vitroView study →}, and a separate extract study reports comparable antioxidant capacity attributed to flavonoids, saponins and lignans ^{13Reference 13Mahdavi S et al. · 2020In vitroThe antioxidant, anticarcinogenic and antimicrobial properties of Verbascum thapsus L. — in vitroView study →}. Most of the activity tracks the phenylethanoid glycoside verbascoside, whose antioxidant behaviour is documented across a large review literature ^{4Reference 4Alipieva K et al. · 2014ReviewVerbascoside — a review of its occurrence, (bio)synthesis and pharmacological significanceView study →}. These are cell-free or cell-line measurements; whether drinking mullein tea raises antioxidant status in people has not been tested.

Gap: Antioxidant capacity is measured in a test tube, not in humans, and the effective in vivo dose is unknown.

The anti-inflammatory reputation is best explained at the constituent level. Verbascoside suppresses inducible nitric oxide synthase (iNOS) and NF-κB signalling in stimulated human THP-1 monocytes, lowering nitric oxide output ^{8Reference 8Speranza L et al. · 2010In vitroAnti-inflammatory effects in THP-1 cells treated with verbascoside — in vitroView study →}. A polyphenol-rich flower extract of the related Verbascum phlomoides — sold interchangeably as “mullein” in parts of Europe — showed anti-inflammatory activity that correlated with its polyphenol content, though this is a different species ^{9Reference 9Grigore A et al. · 2013Correlation between polyphenol content and anti-inflammatory activity of Verbascum phlomoides (mullein)View study →}. Reviews list anti-inflammatory action among mullein’s better-characterised effects, but the direct evidence is cell-based or from constituents rather than whole-herb human studies ^{1,2Reference 1Turker AU · 2005ReviewCommon mullein (Verbascum thapsus L.): recent advances in research — reviewView study →Reference 2Gupta A et al. · 2022ReviewHealth-promoting and disease-mitigating potential of Verbascum thapsus L. (common mullein): a reviewView study →}.

Gap: No whole-herb animal or human anti-inflammatory trial; the strongest data are for an isolated compound and a sibling species.

This is the only indication with human randomised data, and it is heavily qualified. Two paediatric trials tested Otikon, a herbal ear-drop containing Allium sativum (garlic), Verbascum thapsus (mullein), Calendula and Hypericum in olive oil. A 2001 single-centre RCT reported that the herbal drop relieved otitis-media ear pain comparably to an anaesthetic drop ^{5Reference 5Sarrell EM et al. · 2001RCTEfficacy of naturopathic extracts in the management of ear pain associated with acute otitis media — randomised controlled trialView study →}, and a 2003 multicentre double-blind trial found the herbal drop, with or without topical anaesthetic, gave effective and well-tolerated pain relief ^{6Reference 6Sarrell EM et al. · 2003RCTNaturopathic treatment for ear pain in children — randomised, double-blind, multicenter trialView study →}. Because mullein is one of four botanicals in an olive-oil base, neither trial can attribute the benefit to mullein specifically — a caveat directly relevant to the popular “mullein garlic ear oil.” The effect is symptomatic pain relief, not cure of infection.

Gap: Mullein’s individual contribution is unproven — the tested product is a four-herb combination — and no trial has used mullein oil alone.

Mullein extracts show antiviral activity in cell culture. A screen of Nepalese medicinal plants found V. thapsus among those with strong anti-influenza A activity in vitro ^{10Reference 10Rajbhandari M et al. · 2009In vitroAntiviral activity of some plants used in Nepalese traditional medicine — in vitro anti-influenza screenView study →}. A methanolic extract inhibited pseudorabies virus plaque formation with a favourable selectivity index (~31–41), with the strongest effect when virus was pre-incubated with the extract, suggesting activity at the adsorption stage ^{11Reference 11Escobar FM et al. · 2012In vitroAntiviral effect and mode of action of methanolic extract of Verbascum thapsus on pseudorabies virus — in vitroView study →}. Both are laboratory studies against animal or lab viral models; there is no clinical antiviral evidence and no work on human respiratory viruses beyond the influenza screen.

Gap: Entirely in vitro, using whole extracts against surrogate viruses — nothing tested in animals or people.

A single study underpins the traditional “wormwood”-type and antispasmodic uses. A crude aqueous-methanolic extract paralysed and killed roundworms (Ascaridia galli) and tapeworms (Raillietina spiralis) in vitro, and relaxed KCl-contracted rabbit jejunum, supporting both anthelmintic and smooth-muscle-relaxant (antispasmodic) activity ^{14Reference 14Ali N et al. · 2012In vitroAnthelmintic and relaxant activities of Verbascum thapsus mullein — in vitro/ex vivoView study →}. The smooth-muscle relaxation is a plausible mechanistic thread for the herb’s use in spasmodic coughs, but it comes from one isolated-tissue experiment.

Gap: One study, in vitro and ex vivo only — no confirmation in a living animal or human, and no dose translation.

This is mullein’s principal traditional use and its weakest experimental case. The demulcent, cough-soothing action is attributed to the leaf and flower mucilage — polysaccharides that coat and calm irritated mucous membranes — and the expectorant reputation to triterpene saponins thought to thin bronchial secretions ^{1,2Reference 1Turker AU · 2005ReviewCommon mullein (Verbascum thapsus L.): recent advances in research — reviewView study →Reference 2Gupta A et al. · 2022ReviewHealth-promoting and disease-mitigating potential of Verbascum thapsus L. (common mullein): a reviewView study →}. This mechanism is textbook-plausible and the use is documented across European and North American herbal traditions, but there is no clinical or robust preclinical study of mullein for cough, catarrh or bronchial irritation. The claim rests on tradition plus constituent-level reasoning, not on trials.

Gap: No cough or respiratory clinical trial exists; the demulcent/expectorant action is inferred from mucilage and saponin content, not measured.

Cytotoxicity signals are preliminary and inconsistent. Mullein extract inhibited Agrobacterium-induced tumours in the potato-disc assay and showed activity in brine-shrimp toxicity screening ^{3Reference 3Turker AU · 2002In vitroBiological activity of common mullein, a medicinal plant — in vitro (antibacterial, antitumor, toxicity)View study →}, and a methanol extract reduced viability of cancer cells in MTT assays alongside its antioxidant and acetylcholinesterase-inhibitory effects ^{15Reference 15Zhang N et al. · 2023In vitroAnticancer (cytotoxic, MTT) effects of Verbascum thapsus extract — in vitroView study →}. A further extract study reported anticarcinogenic constituents by GC-MS ^{13Reference 13Mahdavi S et al. · 2020In vitroThe antioxidant, anticarcinogenic and antimicrobial properties of Verbascum thapsus L. — in vitroView study →}. These are early-stage in vitro results with no consistent target, cell panel or in vivo follow-up.

Gap: In vitro screening only, with mixed models and no animal or human oncology data.

One recent study characterised mullein tissue oils (leaf, stem, root) and reported antifungal activity in vitro alongside phenolic and fatty-acid profiling ^{16Reference 16Singh R et al. · 2026In vitroPhytochemical profiling and antifungal activity of mullein (Verbascum thapsus) tissue oils — in vitroView study →}. This is a single laboratory report on an oil preparation, not the water or alcohol extracts most people use, so it stands as a preliminary signal rather than a validated action.

Gap: A single in vitro study on tissue oils — unreplicated, and in a preparation form few people actually use.

An ethanol extract of mullein induced apoptosis and inhibited growth and motility of Trichomonas vaginalis in vitro, proposed as a possible alternative to metronidazole ^{17Reference 17Kashan ZF et al. · 2015In vitroEffect of Verbascum thapsus ethanol extract on induction of apoptosis in Trichomonas vaginalis — in vitroView study →}. This is one cell-based study; it aligns loosely with the traditional use for genitourinary and diarrhoeal complaints but has no in vivo or clinical support.

Gap: Single in vitro study against one protozoan — no animal or clinical confirmation.

Mullein has a strong traditional safety record and is generally well tolerated; a methanolic extract showed no genotoxicity in the mouse bone-marrow micronucleus test at doses up to 500 mg/kg ^{18Reference 18Escobar FM et al. · 2011AnimalGenotoxic evaluation of a methanolic extract of Verbascum thapsus using micronucleus test in mouse bone marrow — animal modelView study →}. The fine leaf hairs (trichomes) are a mechanical irritant and can cause itching of the skin, mouth or throat, so leaf teas should be well strained and inhaled smoke may irritate sensitive airways. Because Verbascum thapsus readily accumulates heavy metals from soil and is often gathered from roadsides and disturbed ground, wild-harvested material carries a contamination risk and should come from clean sites ^{19Reference 19Chaplygin V et al. · 2022Influence of soil pollution on the morphology of roots and leaves of Verbascum thapsus L. — heavy-metal accumulationView study →}. No human drug-interaction studies have been conducted, and formal contraindications have not been established.