Bougainvillea, particularly Bougainvillea glabra and Bougainvillea spectabilis, has been used traditionally in various cultures for respiratory ailments, including coughs, asthma, and bronchitis, which relate to the bronchial system. In folk medicine, teas and syrups made from the flowers and leaves are administered to help soothe coughs and clear mucus. Several ethnobotanical surveys, especially from Latin America and parts of Asia, document this traditional use for respiratory tract support.

Scientifically, however, there is limited evidence to validate its effectiveness for supporting the bronchial system. A few small laboratory and animal studies have reported that Bougainvillea extracts may exhibit anti-inflammatory, antimicrobial, and antioxidant properties. One study noted mild anti-inflammatory effects in rat models, which could theoretically help with bronchial inflammation. However, no large-scale clinical trials or robust human studies have confirmed its efficacy or safety for bronchial support.

In summary, the use of Bougainvillea for bronchial support is primarily justified by traditional knowledge, with scant preliminary scientific data. Its rating reflects the reliance on historical use rather than high-quality modern scientific validation.