Asthma is an inflammatory airway disease, which is accompanied by bronchoconstriction, airway hyperresponsiveness, and hypersecretion of mucus, where histamine plays a central role via H1 receptor-mediated smooth muscle contraction and inflammatory signaling. Although the conventional antihistaminic and anti-asthmatics are clinically effective, long-term usage is often characterised by adverse effects, prompting the need for less harmful therapeutic options. Structured literature search was performed in PubMed, Scopus and Google Scholar using relevant search terms, and the studies were identified based on reported antihistaminic, anti-asthmatic, or bronchodilatory effects in peer-reviewed experimental models. This paper critically examines the antihistaminic and anti-asthmatic action of medicinal plants with a focus on the constituent phytochemicals, mechanisms of action, and experimental support. Bioactive compounds such as flavonoids, polyphenols, saponins, and alkaloids can inhibit histamine release, antagonizing H1 receptors, stabilizing mast cells, and inducing bronchodilation. All these pharmacological activities are consistently supported by the evidence in in vitro and in vivo studies provided. Together, medicinal plants are good prospects for the design of complementary or alternative therapeutic interventions in asthma management, but stringent standardization, safety profiling, and clinical validation are necessary to enable their translation to the clinic.
Subi et al. (Wed,) studied this question.