For an 18-month-old with cold and cough, avoid giving strong cough/cold medicines without a doctor?s advice. Keep the child comfortable with warm fluids, steam inhalation, and saline nasal drops to relieve congestion; for fever or discomfort, you can give Paracetamol in the correct dose for age and weight. Monitor closely, and if there is high fever, fast breathing, poor feeding, or symptoms lasting more than a few days, consult a pediatrician promptly.