Visiting a sauna: does inhaling hot dry air reduce common cold symptoms? A randomised controlled trial.

Objective: To compare the efficacy of applying hot dry air versus dry air at room temperature to the throat of patients with a newly acquired common cold using a symptom severity score.

Design, Setting And Participants: A randomised single-blind controlled trial with a treatment duration of 3 days and a follow-up period of 4 days was conducted at a sauna in Berlin, Germany. Between November 2007 and March 2008 and between September 2008 and April 2009, 157 patients with symptoms of the common cold were randomly assigned to an intervention group (n=80) and a control group (n=77).

Interventions: Participants in the intervention group inhaled hot dry air within a hot sauna, dressed in a winter coat, whereas participants in the control group inhaled dry air at room temperature within a hot sauna, also dressed in a winter coat.

Main Outcome Measures: Area under the curve (AUC) summarising symptom severity over time (Days 2, 3, 5 and 7), symptom severity scores for individual days, intake of medication for the common cold and general ill feeling.

Results: No significant difference between groups was observed for AUC representing symptom severity over time (intervention group mean, 31.2 [SEM, 1.8]; control group mean, 35.1 [SEM, 2.3]; group difference, -3.9 [95% CI, -9.7 to 1.9]; P=0.19). However, significant differences between groups were found for medication use on Day 1 (P=0.01), symptom severity score on Day 2 (P=0.04), and participants' ratings of the effectiveness of the therapy on Day 7 (P=0.03).

Conclusion: Inhaling hot air while in a sauna has no significant impact on overall symptom severity of the common cold.

Trial Registration: ClinicalTrials.gov identifier NCT00552981.