The claim: Hot, humidified air can help to cure a cold.
The facts: Inhaling steam or humidified air - a cold remedy as old as the steam kettle - supposedly clears congestion, improves breathing and kills cold viruses, which are sensitive to heat.
Laboratory studies show, for example, that the rhinovirus - the most common cause of colds - is inactivated at temperatures above 43 deg C.
Yet a number of studies have failed to find strong evidence that a dose of heated, humidified air makes any difference for sniffling, sneezing cold sufferers.
In 2006, a report in The Cochrane Database Of Systematic Reviews examined the remedy by combining data from previous studies.
The report included six randomised controlled trials in which cold sufferers were exposed to heated water vapour.
Three of the studies showed benefits, while the others found either a worsening of symptoms or no change at all in antibody levels or shedding of viruses.
One of those studies, carried out at the Cleveland Clinic and published in The Journal Of The American Medical Association in 19994, had 68 cold sufferers sit through 60-minute steam treatments that raised the temperature inside the nose to the required 43 deg C. The treatments had no effect on symptoms like congestion and sneezing.
Ultimately, the Cochrane report concluded that steam inhalation should not be recommended as a remedy for colds until more studies bear out its usefulness.
The bottom line: The evidence for heated or humidified air as a cold treatment is lacking.
- The New York Times