Mullein Side Effects and Warnings

Safety Issues

Mullein leaves and flowers are on the FDA’s GRAS (generally recognized as safe) list, and there have been no credible reports of serious adverse effects. However, mullein seeds contain the insecticide and fish poison rotenone. While rotenone is relatively safe in humans, it does present some toxic risks. If mullein leaf products are contaminated with mullein seeds, long-term use might be harmful.

For this reason, as well as a complete lack of formal safety investigation of mullein, young children, pregnant or nursing women, or those with severe liver or kidney disease should not use mullein for a prolonged period of time.