New research from Wake Forest University Baptist Medical Center in Winston-Salem, NC, suggests Vicks VapoRub, the popular menthol compound used to relieve symptoms of cough and congestion, may instead create respiratory distress in infants and small children.

VapoRub ointment, which according to parent company Procter & Gamble is the top-selling product for ages 2 and up in the cold category, is a topical cough medicine with medicated vapors that works to relieve coughs. It’s available in regular and lemon scents, with three main ingredients: camphor, eucalyptus oil and menthol.

The study appears in this month’s issue of Chest, the peer-reviewed journal of the American College of Chest Physicians. It reports the product may stimulate mucus production and airway inflammation, which can have severe effects on breathing in infants or young children because of their small airway size.

“The ingredients in Vicks can be irritants, causing the body to produce more mucus to protect the airway,” says lead author Bruce K. Rubin, MD, a professor of pediatrics at Brenner Children’s Hospital, part of the Wake Forest medical center. “Infants and young children have airways that are much narrower than those of adults, so any increase in mucus or inflammation can narrow them more severely.”

Vicks VapoRub was first compounded in 1891 in Greensboro, NC, and introduced in 1905 with the name Vick’s Magic Croup Salve. The flu epidemic of 1918 increased sales from $900,000 to $2.9 million in just 1 year, and Procter & Gamble has since marketed the product as “the only thing more powerful than a mother’s touch.”

The salve is widely used to relieve symptoms of colds and congestion, but there are few data supporting an actual clinical benefit, according to Dr. Rubin. Vicks has been reported to cause eye inflammation, mental status changes, lung inflammation, liver damage, airway constriction and allergic reactions.

Dr. Rubin and his colleagues decided to conduct the study after they treated an infant who presented in the emergency room with severe respiratory distress following the application of Vicks directly under her nose.

They first tested it on ferrets, which have an airway anatomy and cellular composition similar to humans. Healthy animals and those with tracheal inflammation (simulating a person with a chest infection) received treatment with Vicks, and the researchers measured its effects on mucus secretion and buildup in the airways, as well as fluid buildup in the lungs.

The studies showed Vicks exposure increased mucus secretion in both normal and inflamed airways. In addition, exposure to the product decreased the rate by which mucus was cleared from the trachea.

The findings support current product labeling, which indicates it should not be used on children 2 years or younger. But many parents continue to use Vicks on their sick kids, often rubbing the salve on the feet or chest, Dr. Rubin says.

“I recommend never putting Vicks in, or under, the nose of anybody—adult or child,” he says. “I also would follow the directions and never use it at all on children under age 2.”

Even when directions are followed, Vicks will make people with congestion more comfortable, but it does nothing to increase airflow or actually relieve congestion, Dr. Rubin adds.

“Some of the ingredients in Vicks, notably the menthol, trick the brain into thinking that it is easier to breathe by triggering a cold sensation, which is processed as indicating more airflow,” he explains. “Vicks may make you feel better, but it can’t help you breathe better.”

In addition to Vicks VapoRub, decongestants are not recommended for young children.

“Mucus is one of the most effective ways that our body protects our air passages like the nose and bronchial tubes,” Dr. Rubin says. “However, lots of mucus and inflammation can cause congestion, especially in little noses. Cough and cold medicines, and decongestants, are dangerous and neither effective nor safe for young children. Medications to dry up nasal passages also have problems.”

The best treatments for congestion are natural and organic: a bit of salt water and gentle rubber-bulb suction, warm drinks or chicken soup “and often, just letting the passage of time heal the child,” Dr. Rubin says.

One important warning: If your child is struggling to breathe, it’s a medical emergency that requires fast assessment by a physician. Don’t delay care!