January 13 (HealthDay News) -- The popular cold remedy Vicks VapoRub may cause airway inflammation that can restrict breathing in infants and toddlers, a new study says.

Doctors at Wake Forest University started their study after treating an 18-month-old girl who had developed severe respiratory distress after the salve had been put directly under her nose to relieve cold symptoms.

"The company is really clear that you don't put it in the nose, and you never use it in kids under 2," said lead researcher Dr. Bruce K. Rubin, professor and vice chair for research at Wake Forest's Department of Pediatrics. "Sure enough, when we stopped all the medicine, the child got much better very quickly."

Rubin's experience prompted him to see if there had been other similar cases. "We encountered a few others that appeared to develop problems after using Vicks VapoRub. Parents never volunteered it, because they always thought it is just something you buy over-the-counter, and it's not a real medicine, because you just rub it on, after all," he said.

Rubin said Vicks VapoRub can make some adults feel better without really making them better. "For kids, because it can induce some inflammation, even a little bit, that little bit might be enough to tip over a child to having problems," he said.

The findings were published in the January issue of the journal Chest.

To test whether Vicks VapoRub could cause respiratory distress, the researchers conducted experiments with ferrets. The animals were chosen because they have airways similar to human airways, Rubin said.

The researchers found that Vicks VapoRub increased mucus production by up to 59 percent; the ability to clear mucus was reduced by 36 percent.

David Bernens, a spokesman for Proctor & Gamble, the makers of Vicks VapoRub, doesn't think one incident involving one child means that the product is unsafe.

"The product is safe and effective when used as directed," he said. "To say it was the Vicks VapoRub that caused the respiratory distress -- I'm not sure we have made that link yet."

Dr. James A. L. Mathers Jr., president of the American College of Chest Physicians, said in an association news release: "Parents should consult with a physician before administering any over-the-counter medicine to infants and young children. Furthermore, the American College of Chest Physicians and several other health-care organizations have concluded that over-the-counter cough and cold medicines can be harmful for infants and young children and are, therefore, not recommended."

In October, major manufacturers and the U.S. Food and Drug Administration announced that over-the-counter cough and cold medicines should not be used by children younger than 4 years old.

Dr. Daniel Craven, a pediatric pulmonologist at University Hospitals Rainbow Babies and Children's Hospital in Cleveland, said parents shouldn't use Vicks VapoRub, because it has no medicinal value and may even be dangerous.

"Previous research has failed to demonstrate any respiratory benefits of VapoRub, and conscientious pediatricians have thus usually tried to dissuade families from spending money on this and similarly ineffective therapies," Craven said. "Although the findings are someone limited, this study raises the possibility that this product may not just be ineffective, but possibly might have adverse respiratory consequences -- particularly if there is an intense exposure -- as when it is applied directly under the nostrils."

SOURCES: Bruce K. Rubin, M.D., professor, vice chair, research, department of pediatrics, Wake Forest University School of Medicine, Winston-Salem, N.C.; Daniel Craven, M.D., pediatric pulmonologist, University Hospitals Case Medical Center's Rainbow Babies and Children's Hospital, Cleveland; David Bernens, spokesman, Proctor & Gamble, Cincinnati; January 2009 Chest