Lastuss-D Syrup is a combination antitussive and antihistaminic formulation containing Chlorpheniramine Maleate 2mg and Dextromethorphan Hydrobromide 10mg per 5ml. Chlorpheniramine Maleate, a first-generation antihistamine, exerts its effect by competitively inhibiting H1 histamine receptors, thereby alleviating allergic symptoms such as rhinorrhea, sneezing, and nasal congestion commonly associated with upper respiratory tract infections. Dextromethorphan Hydrobromide acts centrally on the cough center in the medulla to suppress the cough reflex without causing respiratory depression, making it effective in managing dry, non-productive cough. Lastuss-D Syrup is indicated for symptomatic relief of cough and allergic manifestations related to common cold, bronchitis, and other respiratory tract irritations. It is generally well tolerated; however, caution is advised in patients with a history of hypersensitivity to either component, glaucoma, or respiratory depression. Common adverse effects may include drowsiness, dizziness, dry mouth, and gastrointestinal disturbances. The syrup should be administered as per the prescribed dosage, and use in pediatric and geriatric populations should be under medical supervision. Lastuss-D Syrup provides a balanced approach to managing cough with allergic symptoms, improving patient comfort and respiratory function.