The common cold is the most common infection in humans. Considered trivial, it does not cause complications but leads to significant work absenteeism due to discomfort caused by the symptoms.The common cold is diagnosed according to the symptoms and treatments are mainly symptomatic. New information, especially regarding the effects of cytokines in human beings, now helps to explain some of the symptoms of colds and influenza, such as fever, loss of appetite, malaise, chilliness, headache, and muscle aches and pains. Many of these signs and symptoms are common and are attributed to congestion arising from swelling of the membranes and thickened mucus inside the nose.
The common cold has been treated for decades with inhaled steam in the hope the mucus drain away more easily. Also there is laboratory evidence that the cold virus may be sensitive to heat. No large-scale clinical trials have been undertaken to test the clinical efficacy of this therapy. However, steam inhalation continues to be used, as it provides subjective relief of common cold symptoms. This review reports findings from six trials conducted on 387 participants; 215 participants had a naturally acquired common cold and 172 healthy participants were inoculated with the common cold virus. We combined data from studies reporting the same outcomes. Studies conducted in Europe showed a positive effect whereas those from North America showed no benefit. Reported adverse effects included local discomfort, running of make-up and, in one study, increased nasal resistance. This review found that in some studies inhaling steam helped symptoms; in others it did not. The conclusion is that there is not enough evidence to support steam inhalation for the common cold. None of the studies included children.