A double-blind, randomized study tested the efficacy of steam (technically, heated, humidified air) inhalation in the treatment of common cold symptoms. Two 20-minute treatments spaced 60 to 90 minutes apart were given at the time of enrollment. The active device (Rhinotherm, Netzer-Sereni, Beer Yaacov, Israel) delivered 40 L/min of saturated air at 40°C to 42°C, while the identical-appearing placebo delivered 2 L/min of ambient air at 20°C to 24°C. There were 34 patients in the placebo group and 32 in the active group. Significant improvements in the placebo-treated group were obtained on subjective symptom scores for nasal congestion, nasal drainage, and sneezing on isolated days during the treatment period (40% vs 25% on day 3, 71% vs 60% on day 6, and 100% vs 67% on day 7). Improvement in nasal resistance as measured by rhinomanography was better in the placebo group than in the active group on day 7 (11% vs—6%). Our study demonstrated no beneficial effects of steam inhalation on common cold symptoms.
Macknin ML, Mathew S, VanderBrug Medendorp S. Effect of Inhaling Heated Vapor on Symptoms of the Common Cold. JAMA. 1990;264(8):989-991. doi:10.1001/jama.1990.03450080075034