Rhinorrhea is an annoying symptom of the common cold for which effective therapy is not currently available. Ipratropium bromide (IB) is an anticholinergic drug that has been shown to decrease glandular secretion when applied topically to the nasal mucosa. The purpose of this study was to compare the efficacy and safety of three doses of IB nasal spray versus either vehicle or no treatment in relieving rhinorrhea in patients with naturally acquired colds. Rhinorrhea severity was measured objectively by determining nasal discharge weights and subjectively by means of visual analog scale scores. Compared with either vehicle or no treatment, IB nasal spray produced a significant decrease in the severity of rhinorrhea. A dose of 84 micrograms (two sprays of a 0.06% solution in buffered saline solution) in each nostril was more efficacious than a 42 microgram per nostril dose and only marginally less efficacious than a 168 micrograms per nostril dose. The 84 micrograms per nostril dose also was associated with fewer adverse events than was the higher dose. None of the adverse events related to intranasal IB therapy was of a serious nature. The use of IB nasal spray appears to be a rational and safe approach to relieving rhinorrhea associated with the common cold.