Background: Nasal saline irrigation has been reported to be effective as an adjunctive therapy for allergic rhinitis (AR), but concerns about adverse events, supply problems, and high costs have limited its widespread clinical use. Aqueous 1.8% sodium chloride solution prepared by patients using drinking water (1.8% self-prepared hypertonic nasal saline irrigation; 1.8% SPHNSI) could solve some of these problems, but its clinical efficacy and safety need to be determined.

Objective: We aimed to compare the efficacy and safety of 1.8% SPHNSI and 0.9% commercial isotonic nasal saline irrigation (0.9% CINSI) in patients with AR.

Methods: A randomised, single-blinded, placebo-controlled trial was performed as a pilot study. Seventy-eight patients with AR were included. Each patient was randomised to nasal irrigation with 80 mL of either 1.8% SPHNSI or 0.9% CINSI twice-daily for 4 weeks. Randomised codes were generated using a computer and a block of 4 procedure. The primary outcome was improvement of quality of life scores in Thai patients with allergic
rhino conjunctivitis (Rcq-36). Secondary outcomes were clinical symptoms using total nasal symptom scores (TNSS) and adverse events. All outcomes were assessed by blinded assessors at baseline, week 2, and week 4.

Results: At week 4, nasal irrigation with 1.8% SPHNSI had significantly improved the Rcq-36 score (54% versus 50%; p < 0.032) and congestion symptom score (96% versus 84%; p < 0.018) compared to nasal irrigation with 0.9% CINSI. Adverse events were comparable for both groups at week 4.

Conclusions: This pilot study indicates that regular use of 1.8% SPHNSI in AR patients for 4 weeks is safe and has superior efficacy to 0.9% CINSI for alleviating congestion and improving quality of life scores.