Background: Heated, humidified air has long been used by sufferers of the common cold. The theoretical basis is that steam may help congested mucus drain better and heat may destroy the cold virus as it does in vitro.
Objectives: To assess the effects of inhaling heated water vapour (steam) in the treatment of the common cold by comparing symptoms, viral shedding and nasal resistance.
Search methods: In this updated review we searched CENTRAL 2013, Issue 2, MEDLINE (1966 to February week 4, 2013), EMBASE (1990 to March 2013) and Current Contents (1994 to March 2013).
Selection criteria: Randomised controlled trials (RCTs) using heated water vapour in participants with the common cold or participants with experimentally induced common cold.
Data collection and analysis: The two review authors independently reviewed all retrieved articles and excluded any articles, editorials and abstracts with inadequate outcome descriptions. The studies we included were subjected to a methodological assessment.
Main results: We included six trials (394 trial participants). Three trials in which patient data could be pooled found benefits of steam for symptom relief for the common cold (odds ratio (OR) 0.31; 95% confidence interval (CI) 0.16 to 0.60). However, results on symptom indices were equivocal. No studies demonstrated an exacerbation of clinical symptom scores. One study conducted in the USA demonstrated worsened nasal resistance, while an earlier Israeli study showed improvement. One study examined viral shedding and antibody titres in nasal washings; there was no change in either between treatment and placebo groups. Minor side effects (including discomfort or irritation of the nose) were reported in some studies.
Authors' conclusions: Steam inhalation has not shown any consistent benefits in the treatment of the common cold, hence is not recommended in the routine treatment of common cold symptoms until more double-blind, randomised trials with a standardised treatment modality are conducted.