Great mullein leaves are traditionally used as an expectorant, because it helps expel mucus from the chest. Its expectorant and anti-rheumatic properties cause you to cough and expel mucus from the lungs and throat. It also lubricates your lungs and throat membranes, while it reduces swelling, which can help alleviate irritation.
Moreover, mullein has been traditionally used to remedy bronchitis, asthma, croup, whooping cough, pneumonia, asthma and tuberculosis.
A study published in the “Journal of Ethnopharmacology” in 2002 tested the anti-bacterial activity of mullein leaf extract. The study found that mullein has anti-bacterial activity against Klebsiella pneumonia, coli, and Staphylococcus aureus and epidermidis — two types of bacteria found in the lungs and on the skin.
The same study published in 2012 found that mullein leaves have anti-tumor capabilities. This was only seen in test tubes and there has not been any research done on the anti-cancer activities of mullein in humans.