Cold Symptoms Are Nothing to Blow Your Nose At
Sept. 29, 1999 (San Francisco) -- On average, adults blow their nose 45 times a day during the first three days of a cold, according to doctors at the University of Virginia. But in a new study, they have found that doing so may actually make a cold worse, because the blow propels mucus into the nasal sinuses.
Blowing one's nose creates a significant amount of pressure, according to Jack M. Gwaltney Jr., MD, a professor of internal medicine at the University of Virginia Medical School in Charlottesville. In fact, coughing and sneezing generate only one-tenth as much pressure, he says. Because of this increased pressure, "each nose blow can propel approximately one millimeter of mucus into the sinuses," says Gwaltney. Since nasal mucus may contain viruses or bacteria, this can increase the severity of a cold, he says.
The practical implication of these findings, the authors say in a press release accompanying the presentation, is that "there is a potential risk for each nose blow to introduce nasal secretions into the sinuses." To prevent mucus accumulation, says Gwaltney, "use a strategy of early, continuous treatment. The minute you think you're starting a cold, start treating it. Don't wait around a day or two to see if it will go away."
The impetus for this study, presented here at the 39th Interscience Conference on Antimicrobial Agents and Chemotherapy, came when Gwaltney and his colleagues looked at CAT scans of the nasal passages of people with colds. All of the patients had mucus in their sinuses, Gwaltney says, but in one patient they noticed bubbles. "We concluded the mucus had to be blown in there," he tells WebMD.
To test this hypothesis, the investigators placed tiny pressure transducers in the nasal cavities of four volunteers. They enlisted the aid of an engineering instructor, who developed a mathematical model for calculating the likelihood of mucus entering the nasal sinuses each time a volunteer coughed, sneezed, or blew their nose.
In 10 more volunteers they instilled a special dye in the nasal passages that allowed them to see the nasal secretions on the CAT scans. Sure enough, says Gwaltney, "every time the volunteers blew their nose we saw dye in their sinuses." They did not see mucus in the sinuses following coughing or sneezing, a finding that surprised Gwaltney because, he explains, sneezing also can generate considerable pressure in the head.