Plantain (Plantago major), commonly known as common or English plantain, has a long history of use in traditional herbal medicine for supporting respiratory health, including the bronchial system. Historical records show that plantain leaves were used in traditional European and Native American medicine to soothe coughs, ease irritation of the throat, and manage mild bronchial discomfort. This use is primarily attributed to the plant’s mucilage content, which can coat mucous membranes and provide a soothing effect. Additionally, plantain contains bioactive compounds such as aucubin (an iridoid glycoside) and allantoin, which may contribute to its anti-inflammatory and mild antimicrobial properties.

Scientific research on Plantago major's direct effects on human bronchial health is limited, but some in vitro and animal studies suggest anti-inflammatory and soothing effects relevant to respiratory tissues. For example, some extracts have demonstrated the ability to reduce inflammation and inhibit certain bacteria, which could indirectly support bronchial health. However, well-designed clinical trials in humans are lacking, so most evidence supporting its use for the bronchial system remains traditional rather than firmly scientific. Thus, while traditional usage is robust and there are plausible mechanisms of action, the evidence level is moderate due to the lack of rigorous human studies.