Steam inhalation is perhaps one of the most widely prevalent home-based practices, amongst laity and the professionals; based on the perception that warm humidified air provides subjective relief of respiratory symptoms, by loosening the respiratory secretions(1). Advances in understanding of pathophysiology of respiratory infections/illnesses and development of specific therapy; make it important to examine this age-old ‘remedy’ in the light of modern evidence-based health-care practice.

The Cochrane review on common cold(9) was updated till May 2006; no additional trials are identified. Hence the data therein can be considered current, but a few methodological errors necessitate a fresh review.

Data from the common cold trials were heterogeneous (in terms of participants, outcome measures, timing of measurement, and baseline status. One trial(2) suggested subjective improvement with steam; another(3) suggested the opposite and yet another showed no difference(5). Meta-analysis did not show benefit (RR for non-improvement=1.78; 95%CI 0.01-226.51). The single trial in children with pneumonia showed no benefit of steam, but some benefit in bronchiolitis(4). No data were found pertaining to croup and sore throat. There was limited data on the adverse events associated with steam inhalation especially the risk of burns/scalds in infants and children.

At first glance, this EURECA systematic review does not appear to present significant new findings in terms of management, except that there are no scientific grounds to encourage steam inhalation in children. However, it presents the opportunity to critically appraise a few important issues.

Is steam inhalation relevant in modern practice? It must be noted that the practice of steam inhalation could have been relatively justifiable at a time when there was limited understanding of pathophysiologic mechanisms in various respiratory tract illnesses; coupled with limited therapeutic options. Presently, both situations have dramatically changed for most respiratory conditions.

Subjective versus objective improvement: It is interesting that subjective improvement/perception of relief; often does not correlate with objective measurements. This raises the tricky issue of whether, ‘feeling better’ is superior to ‘being better’. In the context of conditions as diverse as acute common cold to chronic arthritis, the former cannot be ignored, and may take precedence over precise objective measurements. On the other hand, for most other clinical conditions, demonstration of subjective improvement may be inadequate to prove that an intervention works. The precise balance between subjective and objective outcome measures in common cold, is not clear. Moreover, the subjective and objective outcome measures reported in adult studies are difficult to replicate in children, necessitating less robust methods to evaluate benefit. This could alter the results of pediatric trials significantly.

Is there any harm in recommending steam inhalation? Many care-givers (physicians and parents) may prefer to opt in favour of steam inhalation, based on personal (favourable) experiences, and might argue that this outweighs the (absence of) data from research studies. It must be emphasized that one of the goals of evidence-based health-care is to protect patients from precisely this tendency.

Most of the included trials recruited adults, delivered hot humidified air, through commercial devices and used complex objective measurements. The lone pediatric trial was limited in terms of quality and quantity, to draw a meaningful conclusion in favor of steam inhalation. Hence strictly speaking, the data is not extendible to the population of interest.

Funding: None.

Competing interest: None stated.

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