Malabar Nut Tree Leaf Extract, derived from Justicia adhatoda, has a long history of use in Ayurvedic and traditional medicine for the treatment of respiratory conditions, including cough (particularly spastic or dry coughs). The leaves contain active compounds such as vasicine and vasicinone, which have been scientifically investigated for their bronchodilator, expectorant, and antitussive (cough-suppressing) effects.

Multiple preclinical studies have demonstrated that vasicine exerts significant bronchodilatory effects, relaxes tracheal muscles, and reduces the frequency and severity of cough induced by various irritants in animal models. Additionally, some clinical studies and trials in humans have shown that Malabar Nut extracts can help alleviate symptoms of cough, ease breathing, and improve overall lung function. For example, randomized controlled trials and observational studies in patients with chronic bronchitis or cough have reported symptomatic improvement and reduction in cough frequency with the use of standardized Justicia adhatoda extracts or formulations containing its alkaloids.

Regulatory authorities in several countries, including India, recognize Malabar Nut as an antitussive ingredient and it is included in various over-the-counter cough syrup formulations. However, most of the human data comes from relatively small-scale or non-blinded studies, so while the mechanistic and empirical evidence is strong, more robust clinical trials would further solidify its efficacy profile.