Objectives/Hypothesis: We aimed to study the effect of alkalinity of isotonic nasal saline irrigation on nasal symptoms, mucociliary clearance, nasal patency, and patient’s preference in patients with allergic rhinitis (AR).

Study Design: A double-blind, randomized, three-arm crossover study.

Methods: Patients with AR were enrolled. Three kinds of isotonic nasal saline irrigations: nonbuffered (pH 6.2–6.4), buffered with mild alkalinity (pH 7.2–7.4), and buffered with alkalinity (pH 8.2–8.4) were given one at a time, in different orders. Patients rinsed their nose with 240 ml of one solution twice daily for 10 days and then swapped to the others. The washout period was at least 5 days. Primary outcomes were nasal symptoms, mucociliary clearance time, and nasal patency. Outcomes were compared between baseline and posttreatment and also between various kinds of solution. Secondary outcomes were patients’ preference and adverse events.

Results: Thirty-six subjects entered the study, and there were no dropouts. Overall nasal symptom was significantly improved from baseline (P¼0.03) only by buffered solution with mild alkalinity. Sneezing was significantly improved from baseline (P¼0.04) only by buffered solution with alkalinity. No other significant improvements were achieved by any solution. When comparing between the three nasal irrigations, there were no differences in all parameters. The patients significantly preferred the buffered solution with mild alkalinity (P¼0.02).

Conclusions: Buffered isotonic saline with some degree of alkalinity may improve nasal symptoms. Isotonic saline irrigations, regardless of alkalinity, may not improve mucociliary function and nasal patency. Buffered isotonic saline with mild alkalinity is the most preferred.