As sniffles and coughs stalk cold and flu sufferers this winter, plenty of Americans will reach for that smelly viscous goo, Vicks VapoRub, in hopes of finding relief for their congestion. Don’t bother, a new study suggests.<!—->

Physicians were called in to diagnose what was behind the wheezing and severe difficulty breathing in an 18-month-old girl that had been admitted to the <!—->WakeForestUniversityBaptistMedicalCenter’s emergency room. The child’s grandparents mentioned that her respiratory distress developed within 45 minutes of their placing a little Vicks under her nose. They’d hoped it would help her cope with the congestion associated with a nasty head cold.

Bruce Rubin and his team treated the girl with oxygen and kept her under observation for a day, then sent her home. But concerned about why she should have had such a severe reaction, they decided to conduct a little study in ferrets, which have an airway anatomy similar to that in people. Some of the rodents were healthy when they were exposed to the salve’s vapors, others were first treated with an inflammatory agent to simulate a respiratory infection.

Under both circumstances, the salve provoked an increase in airway mucus, although the biggest effect — a 14 percent increase — occurred in the initially healthy animals. The physicians’ speculation: The inflammatory agent used on the other ferrets had already triggered mucus production, perhaps to near maximum capacity. Rubin and his team report their findings in the January Chest, a journal published by the American College of Chest Physicians.

The ferret data would appear to explain, at least in part, what they witnessed in the little girl, the WakeForest researchers say. Adds Rubin: “I recommend never putting Vicks in, or under, the nose of anybody — adult or child. I also would follow the directions and never use it at all on children under age 2.” Generic versions of the product would likely have the same effect, he notes.

Ironically, Rubin’s team reports, tests by others have shown that the salve tends to provide comfort to cold sufferers. Its active ingredients — menthol, camphor and eucalyptus — tend to provide a sense of cooling and improved airflow while actually doing the opposite. The magnitude of airway reduction associated with the extra mucus “may be of little physiologic consequence in older children and adults, but in infants and small children this potentially can lead to respiratory distress.”

Procter & Gamble, which makes Vicks VapoRub issued a formal response saying: “The animal findings are of unknown human clinical relevance.” It added that the safety of its salve, which has been marketed for more than a century, “has been demonstrated in multiple human clinical trials, which have included more than a thousand children ages one month to 12 years.”

Janet Raloff is the Editor, Digital of Science News Explores, a daily online magazine for middle school students. She started at Science News in 1977 as the environment and policy writer, specializing in toxicology. To her never-ending surprise, her daughter became a toxicologist.