How Strong Is the Evidence for Mullein?
The easiest way to misunderstand herbal research is to treat every type of evidence as though it has the same meaning.
For mullein, the evidence can be divided into four major levels.
Traditional Use
Documents how mullein has been used historically and whether that use is formally recognized by herbal medicine authorities. It does not by itself prove modern clinical effectiveness.
Laboratory Research
Studies plant compounds, extracts, cells, microbes or biochemical activity. Useful for generating hypotheses, but laboratory effects do not automatically translate into benefits in human lungs.
Animal / Preclinical Evidence
Can help researchers explore biological mechanisms and safety questions. Animal findings still require appropriate human research before clinical benefits can be established.
Human Clinical Evidence
Human trials are the most relevant evidence for determining whether a preparation actually improves symptoms, lung function or disease outcomes in people. This is currently the major evidence gap for broad mullein lung-health claims.
Current Evidence Snapshot
| Claim or topic | Evidence status | What we can reasonably say |
|---|---|---|
| Mullein flower for dry cough / cold | Traditional-use evidence | The EMA recognizes long-standing traditional use of mullein flower for relief of sore throat associated with dry cough and cold. |
| Mullein and mucus / phlegm | Limited clinical evidence | Mullein has a traditional expectorant reputation, but strong human evidence showing reliable mucus clearance is lacking. |
| General lung-function improvement | Not established | High-quality human evidence showing broad improvement in objective lung function has not been established. |
| Lung cleansing or detox | Not established | There is no good clinical evidence that mullein removes cigarette tar, pollution particles or unspecified toxins from lung tissue. |
| Repairing smoking damage | Not established | Mullein has not been shown to reverse emphysema, regenerate damaged alveoli or restore structural lung damage caused by smoking. |
| Asthma | Not established treatment | Traditional or experimental interest does not establish mullein as a clinically proven bronchodilator or asthma treatment. |
| COPD | Not established treatment | Mullein has not been clinically established as a treatment that reverses COPD or replaces evidence-based respiratory care. |
| Smoking mullein | Different evidence question | Traditional oral-use evidence cannot be transferred to burned plant smoke. Combustion creates additional exposures. |
| Mullein vape | Different evidence question | Evidence from teas, flowers or oral extracts cannot automatically be transferred to heated aerosol products. |
The Strongest Formal Evidence: Mullein Flower
Verbasci flos — Mullein Flower
The European Medicines Agency's Committee on Herbal Medicinal Products concluded that, based on long-standing use, mullein flower medicines can be used for relief of sore throat associated with dry cough and cold.
Crucially, the EMA describes this conclusion as traditional use. It also notes the lack of clinical studies with mullein flower medicines.
This makes the EMA monograph useful evidence of established traditional use — but not proof that mullein broadly treats lung disease or improves lung function.
What Do Scientific Reviews Say?
Gupta et al. — Review of Verbascum thapsus
A 2022 review by Gupta and colleagues summarizes the traditional importance, phytochemistry and experimental research surrounding common mullein.
The review discusses numerous compounds and biological activities reported in the scientific literature, helping explain why the plant continues to attract research interest.
A review of laboratory, traditional and preclinical literature should not, however, be interpreted as a randomized human trial demonstrating broad lung-health benefits.
Turker & Gurel — Common Mullein Research Review
This earlier scientific review documents the long history of common mullein and summarizes research available at that time, including traditional respiratory uses.
It is useful for understanding the historical and scientific context of the herb, but it does not establish that every traditional respiratory claim has been confirmed in modern human clinical trials.
Laboratory Findings Are Not the Same as Human Benefits
Mullein research includes investigation of plant constituents and biological activities in laboratory or experimental models.
These types of studies are valuable because they can identify compounds, mechanisms and questions worth studying further.
But a compound showing activity in a test tube does not automatically mean:
- a cup of mullein tea produces the same concentration in the human body;
- a capsule improves human lung function;
- an extract treats respiratory disease;
- or an inhaled mullein product produces the same biological effect.
This difference between biological plausibility and demonstrated clinical benefit is one of the most important principles on this site.
Why Product Form Matters in Mullein Research
“Mullein” is not one standardized intervention.
A study or traditional-use document may involve a particular:
- plant species;
- plant part;
- flower or leaf preparation;
- extract solvent;
- extract concentration;
- dose;
- route of administration;
- or combination with other ingredients.
This matters because results from one preparation should not automatically be applied to a completely different commercial product.
The U.S. National Center for Complementary and Integrative Health also notes that supplements sold in stores or online can differ in important ways from products tested in research.
Read NCCIH guidance on dietary and herbal supplements →
Research by Lung-Health Question
Research by Mullein Form
How We Evaluate Mullein Claims
When we review a mullein claim, we ask five questions.
1. What exact preparation was studied?
Flower, leaf, tea, extract, capsule, smoke and aerosol are not interchangeable.
2. What kind of evidence is it?
Traditional use, laboratory studies, animal models, observational evidence and randomized human trials answer different questions.
3. Was the outcome actually measured?
Claims such as “lung detox,” “better breathing” or “lung support” can be vague. Stronger evidence uses measurable outcomes such as symptom scores, lung-function tests or clearly defined clinical endpoints.
4. Does the evidence match the claim?
A study showing antimicrobial activity in a laboratory cannot prove that a commercial supplement treats a respiratory infection in people.
5. Are risks and uncertainty presented too?
A responsible evidence summary should explain what is unknown, not only what sounds promising.
Major Gaps in Mullein Research
Several questions would require better human studies before strong conclusions could be made.
- Does a standardized mullein preparation improve cough compared with placebo?
- Does mullein measurably change mucus production or mucus clearance?
- Does it change objective lung-function measurements?
- What doses and preparations have the best-defined safety profiles?
- How do flower and leaf preparations differ clinically?
- What are the clinically meaningful herb-drug interactions?
- What are the long-term respiratory effects of inhaled mullein-containing aerosols?
Until questions like these have stronger human evidence, broad claims should remain appropriately cautious.
Safety Evidence Is Part of the Research
Evidence-based evaluation is not only about whether something may work. It also includes product quality, interactions, dose, population and route of exposure.
NCCIH notes that herbal supplements may interact with medications and that commercial products can differ from products tested in research.
This is especially relevant for people who:
- take prescription or over-the-counter medications;
- use several supplements at once;
- are pregnant or breastfeeding;
- are considering herbal products for children;
- have chronic respiratory disease;
- or have persistent or worsening respiratory symptoms.
See our dedicated Mullein Safety guide .
Frequently Asked Research Questions
Is there scientific research on mullein?
Is mullein clinically proven for lung health?
Are there human trials showing mullein improves lung function?
Does laboratory research prove mullein works in people?
Does research prove mullein clears mucus?
Does research show mullein cleans smokers' lungs?
Can research on mullein tea be applied to mullein vape?
Which part of mullein has the strongest formal evidence?
Key References
European Medicines Agency / HMPC.
Assessment report on Verbascum thapsus L., V. densiflorum Bertol. and V. phlomoides L., flos.
Gupta A, Atkinson AN, Pandey AK, Bishayee A.
Health-promoting and disease-mitigating potential of Verbascum thapsus L. (common mullein): A review. Phytotherapy Research. 2022;36(4):1507–1522.
Turker AU, Gurel E.
Common mullein (Verbascum thapsus L.): recent advances in research. Phytotherapy Research. 2005;19(9):733–739.