Short answer: nobody has tested it. That’s why we’re running a study.
Short answer: nobody has tested whether mullein helps a smoker’s cough. Not once. There are two human trials of mullein at all, and neither is about lungs.
Mullein leaf has been used for coughs and sore throats for a long time. The EU’s herbal medicines committee lists relief of sore throat with dry cough as a traditional use — meaning long-standing use, not trial results. Today it is sold as tea, drops, gummies and capsules, often with lung claims on the label.
Evidence checked 2026-10-21. Grades are calculated from the studies listed, by fixed rules.
No human trial has tested it. The EU herbal monograph lists relief of sore throat with dry cough and cold as a TRADITIONAL use — based on long-standing use, not on trials.
No human trial has tested it, and no study has measured lung function after mullein. Nothing undoes smoking damage except stopping.
No supplement undoes what smoke does to the lungs. The one thing that does is stopping, and it is never too late to start.
Free help to stop smoking: smokefree.gov · 1-800-QUIT-NOW (1-800-784-8669).
Adults who smoke daily and have had a cough for two months or more take mullein capsules for four weeks and identical-looking placebo capsules for four weeks, in random order, without knowing which is which. Cough is measured with a standard questionnaire. The plan is registered before anyone joins, and the result is published here whatever it shows — including “it did nothing”. About the study.
The study is not open yet. It opens only after an independent ethics board approves the plan, and the plan is registered publicly before anyone joins. This page will say when.