The differential diagnosis of rhinorrhea

Rhinorrhea disrupts the quality of life of a large segment of the population. The first step to treating it properly is to make an accurate diagnosis of its underlying cause. This is not always a simple proposition, however, because rhinorrhea has many causes that can easily be confused in clinical practice. Diagnosis has come to rely increasingly on testing, but test costs add significantly to the health-care burden. This article reviews the use of medical logic in the differential diagnosis of rhinorrhea and describes the relative usefulness of various testing methods.