You may take Corex DX Syrup for short-term relief of a dry cough. It contains chlorpheniramine and dextromethorphan, which work by reducing the cough reflex and help relieve allergy-related symptoms such as sneezing, a runny nose, and watery eyes. However, it may cause drowsiness, dizziness and dry mouth, so it should be taken at night and you should avoid driving or alcohol. It is not suitable if you have a chesty cough with mucus, as it may prevent phlegm from clearing. Your nighttime worsening cough may also be due to post-nasal drip, allergies or acid reflux. Drink warm fluids, use steam inhalation and keep your head elevated while sleeping. If your symptoms persist for more than one week or you develop fever, breathlessness or chest pain, please consult a doctor for proper evaluation.