Susanne van de Hei, Steven McKinstry, George Bardsley, Mark Weatherall, Richard Beasley, James Fingleton

To determine the feasibility of a randomised controlled trial (RCT) of rhinothermy for the common cold. Open label, randomised, controlled feasibility study. Single-centre research institute in New Zealand recruiting participants from the community. 30 adult participants with symptoms of a common cold, presenting within 48 hours of the onset of symptoms. Participants were randomly assigned 2:1 to receive either 35 L/min of 100% humidified air at 41°C via high flow nasal cannulae, 2 hours per day for up to 5 days (rhinothermy), or vitamin C 250 mg daily for 5 days (control). The primary outcome was the proportion of screened candidates who were randomised. Secondary outcomes included: proportion of randomised participants who completed the study; modified Jackson scores from randomisation to 10 days after initiation of randomised regimen; time until feeling 'a lot better' compared with study entry; time until resolution of symptoms or symptom score at 10 days postrandomisation; proportion of organisms identified by PCR analysis of nasal swabs taken at baseline; the patterns of use of the rhinothermy device; estimated adherence of the control group; and rhinothermy device tolerability. In all 30/79 (38%, 95% CI 27% to 50%) of potential participants screened for eligibility were randomised. Rhinothermy was well tolerated, and all randomised participants completed the study (100%, 95% CI 88% to 100%). The reduction from baseline in the modified Jackson score was greater with rhinothermy compared with control at days 2, 3, 4, 5 and 6, with the maximum difference at day 4 (-6.4, 95% CI -9.4 to -3.3). The substantial clinical benefit threshold for modified Jackson score was a 5-unit change. This study shows that an RCT of rhinothermy compared with low-dose vitamin C in the treatment of the common cold is feasible. ACTRN12616000470493; Results.