Ontus-D Syrup is a combination pharmaceutical formulation containing Phenylephrine (5mg/5ml), Chlorpheniramine Maleate (2mg/5ml), and Dextromethorphan Hydrobromide (10mg/5ml), designed for the symptomatic relief of upper respiratory tract conditions. Phenylephrine acts as a selective alpha-1 adrenergic receptor agonist, providing effective nasal decongestion by vasoconstriction of the nasal mucosa. Chlorpheniramine Maleate is a first-generation antihistamine that alleviates allergic symptoms such as rhinorrhea, sneezing, and itching by blocking H1 histamine receptors. Dextromethorphan Hydrobromide serves as a centrally acting antitussive agent, suppressing the cough reflex by acting on the medullary cough center without causing significant respiratory depression. Ontus-D Syrup is indicated for the management of cough, cold, and allergic rhinitis symptoms, including nasal congestion, runny nose, and dry cough. It is suitable for use in adults and children above the recommended age as per prescribing information. Caution is advised in patients with hypertension, glaucoma, or those taking monoamine oxidase inhibitors. Adverse effects may include drowsiness, dizziness, dry mouth, and gastrointestinal disturbances. Consultation with a healthcare professional is recommended before use to ensure safety and appropriate dosing.