Chronic Dry Cough with Dry Throat: Treatment Principle

An 18-year-old young man has coughed for one month after an exterior illness. The cough is short and dry with scant sticky sputum, worse in the afternoon with throat dryness and occasional hoarseness. He has no obvious aversion to cold or fever. Tongue is red with scant coat. Pulse is thin and rapid. What is the best treatment principle?