Evidence Trace, complete trial record
In plain terms
In plain terms: Steam Inhalation (for colds and sinus symptoms) has been tested in human trials aimed at the relevant outcome and did not show benefit at the doses and durations studied. The animal research may be encouraging, but it has not yet translated to humans in these trials.
Steam Inhalation (for colds and sinus symptoms)
D
Not shown: no human trial shows benefit
Route 2: tested in humans; benefit not shown
The endpoint this grade is based on: self_report
The evidence as the record states it
Singh et al. (Cochrane Database Syst Rev, 2017; PMID 28849871): six trials, 387 people with colds; no benefit shown on symptoms, viral shedding or nasal resistance, low-quality evidence. Little et al. (CMAJ, 2016; PMID 27431306): 871 adults with chronic or recurrent sinus symptoms; advice to use steam did not reduce sinus disability, though headache was lower. Baartmans et al. (Br J Gen Pract, 2012; PMID 22781995), Al Himdani et al. (Br J Gen Pract, 2016; PMID 26917659) and Scarborough et al. (Burns, 2021; PMID 32943275): burn center series of scalds from steam inhalation, most in children. Grade D, Route 2.
PMID 28849871 PMID 27431306 PMID 22781995 PMID 26917659 PMID 32943275
Trials showing no benefit
- Endpoint
- Common cold symptom relief
- Population
- Six trials, 387 people
No benefit shown
Low. Random-effects analysis null; review concludes no benefit or harm shown.
- Endpoint
- Rhinosinusitis Disability Index
- Population
- 871 adults with chronic or recurrent sinus symptoms
No benefit shown
Moderate. Large pragmatic trial.
Evidence by specific use
Common cold symptoms
Grade D
Singh et al. (Cochrane Database Syst Rev, 2017; PMID 28849871): six trials, 387 participants. Whether steam eases cold symptoms was uncertain: the fixed-effect analysis showed a benefit (odds ratio 0.30), the random-effects analysis did not (0.22, 95% CI 0.03 to 1.95), and the share of people reporting that their symptoms resolved was not higher with steam (0.58, 95% CI 0.28 to 1.18). Viral shedding did not differ. The evidence was rated low quality. The review concluded that current evidence shows no benefit or harm. Tested, no benefit.
PMID 28849871
Chronic or recurrent sinus symptoms
Grade D
Little et al. (CMAJ, 2016; PMID 27431306): 871 adults with chronic or recurrent sinus symptoms randomized to usual care, daily saline nasal irrigation, daily steam inhalation or both. Steam inhalation reduced headache but had no significant effect on sinus disability or the other outcomes; nasal irrigation helped modestly. Tested, no benefit.
PMID 27431306
Why Grade D Route 2 and not Grade C
Grade D Route 2 applies when a compound has been tested in humans and benefit was not shown. Steam Inhalation (for colds and sinus symptoms) has been tested in 2 human trials on endpoints relevant to the claim being evaluated, and the primary endpoint was not met.
A randomized, placebo-controlled trial pre-specifying a meaningful clinical or functional endpoint and demonstrating statistically significant benefit would move this to Grade C or higher, depending on effect size, population size, and whether it is independently replicated.
What this grade covers and what it does not
Grade D on Route 2: tested, no benefit. The Cochrane review of six trials in the common cold could not show that breathing steam eases symptoms: the result depended on the statistical model chosen, and fewer people reported their symptoms resolving with steam than without, though not significantly (Singh et al., 2017; PMID 28849871). The largest trial, in 871 adults with chronic or recurrent sinus symptoms, found no effect on sinus disability at 3 or 6 months (Little et al., 2016; PMID 27431306). The harm is documented: burn centers report scalds from tipped bowls of hot water every year, most often in children (PMID 22781995; PMID 26917659). WHAT THIS GRADE DOES NOT COVER: sitting in a steam room, which is a different exposure and has its own record; humidified oxygen or nasal high-flow devices used in hospital care.
What would move this grade
A randomized, placebo-controlled trial pre-specifying a clinical aging endpoint and demonstrating statistically significant benefit on that primary endpoint would be sufficient to move this to Grade C or higher, depending on effect size and population.
How to track whether this is working
Nothing validated. Symptom days, if steam is used, against the 7 to 10 days a cold usually lasts.