Double-blind randomised trial of saline solution for gargling and nasal rinsing in SARS-CoV-2 infection

Previous studies have shown that hypertonic saline nasal irrigation and gargling reduced the duration of symptoms in upper respiratory infections caused by coronavirus. This study aims to investigate the effects of two saline regimens on symptoms associated with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2).

Between 2020 and 2022, individuals aged 18-65 years who tested positive for SARS-CoV-2 infection via polymerase chain reaction (PCR) were randomly assigned to either low- or high-saline regimens for 14 days. The low-saline solutions contained 2.13 g of salt dissolved in eight ounces of warm water, while the high-saline solution contained six grams of salt dissolved in eight ounces of warm water. Participants gargled and rinsed their nasal passages four times a day for 14 days. Primary outcomes assessed included frequency and duration of SARS-CoV-2 symptoms, while secondary outcomes included hospital or intensive care unit (ICU) admission, need for mechanical ventilatory support, or mortality rates. Exclusion criteria included chronic hypertension or participation in other interventional studies.

Fifty-eight individuals were allocated to the low (n = 27) or high (n = 28) saline regimens; with three lost to follow-up. There were no significant differences in primary or secondary outcomes between these groups. Comparatively, during the study period, 9398 individuals with confirmed SARS-CoV-2 infection by positive PCR test were observed as a reference group. Hospitalisation rates in the low-saline (18.5%) and high-saline (21.4%) regimens were significantly lower than in the reference group (58.8%; P < 0.001), while no significant differences were observed in other outcomes among these groups.

Low and high saline regimens for gargling and nasal rinsing show similar effectiveness in reducing the frequency and duration of symptoms related to SARS-CoV-2 infection. Both saline regimens are associated with lower hospitalisation rates compared to individuals not using gargling or nasal rinsing in those infected by SARS-CoV-2.