A 35-year-old woman has a history of nasal congestion on most days of the year, dating back to her late teens. She has chronic nasal drainage, which is clear and thick. Her congestion is worst in the late summer and early fall and again in the early spring; at these times, she also has sneezing, nasal itching, and cough. Five years ago, she had an episode of shortness of breath with wheezing on a day when her nasal symptoms were severe, but this episode resolved spontaneously and has not recurred. Her eyes do not bother her. Over-the-counter oral antihistamines help her symptoms a little, as do nasal decongestants, which she uses occasionally. Her 6-year-old son has similar symptoms. How should this case be managed?