drug expectorant chebi_ontology CHEBI:77035 expectorants Compounds that are considered to increase the volume of secretions in the respiratory tract, so facilitating their removal by ciliary action and coughing. Compare with mucolytics, which decrease the viscosity of mucus, facilitating its removal by ciliary action and expectoration, and antitussives, which suppress the cough reflex. PMID:17594730