Plectranthus amboinicus, commonly known as Indian borage or Mexican mint, has a long history of traditional use for supporting the respiratory or bronchial system in various cultures, particularly in South Asia, Africa, and the Caribbean. Traditional medicine systems utilize its leaves for treating coughs, asthma, bronchitis, and other respiratory ailments. The leaves are often crushed and inhaled, brewed as a tea, or used in syrups to help soothe sore throats, reduce cough, and ease breathing difficulties.

The justification for its use comes from ethnobotanical records and anecdotal reports rather than rigorous scientific validation. Some laboratory studies have identified that the plant contains essential oils (such as thymol, carvacrol, and eugenol) known for their antimicrobial and anti-inflammatory properties, which might theoretically benefit the bronchial system. However, clinical trials in humans are lacking, and the evidence supporting its efficacy is mostly confined to animal studies or in vitro experiments. As a result, while its use is well-established in traditional medicine, scientific evidence confirming its effectiveness for bronchial support is limited.

In summary, the use of Plectranthus amboinicus for bronchial support is based primarily on tradition, with modest supporting evidence from phytochemical and preclinical investigations, but not yet substantiated by high-quality clinical research.