The leaves and flowers of mullein are typically used in herbal preparations. The leaves are collected in late spring before flowering, the flowers between July and September, and the roots in March or October. Mullein leaves and flowers are classified in herbal literature as expectorants and demulcents. Historically, mullein has been used as a remedy for the respiratory tract, particularly in cases of irritating coughs with bronchial congestion. As such, bronchitis sufferers often find relief with this herb, particularly when combined with white horehound and lobelia .
Some herbal texts extend the therapeutic use to pneumonia and asthma .
Because of its mucilage content, mullein has also been used topically as a soothing emollient for inflammatory skin conditions and burns. The flowers are also considered mildly calming. 3 Mullein root is considered primarily a mild diuretic in the few traditional sources that mention it at all. The mucilaginous constituents are primarily responsible for the soothing actions on mucous membranes. The saponins may be responsible for the expectorant actions of mullein.