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A new study raised concerns recently over safety of the popular ointment Vicks VapoRub in young children. Wake Forest University researchers report that the salve, which is used to relieve symptoms of cough and chest congestion, may actually stimulate mucus production and airway inflammation in infants and toddlers . However, the results are far from conclusive as the study was based on the case of a single child and 15 animals. Moreover, many of the results of the study have been incorrectly reported by the media.
Doctors at Wake Forest became interested in the effects of Vicks VapoRub on small children after they treated a previously healthy 18-month old girl who developed severe respiratory distress after the ointment was rubbed under her nose. The researchers used ferrets, which have an airway anatomy and cellular composition similar to that of humans, to measure the effects of Vicks VapoRub on mucus secretion, transport and clearance in the airways, and fluid build up in the lungs.
Three studies were performed:
- The first study evaluated the effects of Vicks VapoRub relative to water-soluble jelly (K-Y Jelly) as a control, on mucin secretion, mucociliary transport velocity (meaning the time it takes to transport mucus 3 mm, reported in millimeters per minute) and mucus clearance (as measured by muciliary beat frequency) in tracheal tissue isolated from 15 ferrets. These experiments were performed in vitro (meaning in a dish with isolated tissue and not in a living animal).
- The second study was performed in vivo (meaning on live animals) and evaluated the effects of Vicks VapoRub on a normal airway, measuring mucin secretion, mucociliary transport velocity and fluid build up in the lungs of 14 ferrets shallowly intubated for 90 minutes with an endotracheal tube that had a small volume of the salve or jelly on the inside the exterior connector.
- The third study, also performed in vivo, evaluated the effects of Vicks VapoRub on an inflamed airway (simulating a person with a chest infection) and measured mucin secretion, mucociliary transport velocity and fluid build up in the lungs of 8 ferrets that were again intubated with an endotracheal tube and exposed to the ointment or water-soluble jelly as a control.
The researchers found that Vicks VapoRub increased mucin secretion in ferret tracheal tissue by 59% over controls. There was no significant difference in mucociliary transport velocity comparing Vicks VapoRub to control samples. Mucus clearance in ferret tracheal tissue decreased by 36% relative to controls.
In vivo, Vicks VapoRub increased mucin secretion in a normal airway by 14% and in an inflamed airway by 7.8%; however, the differences were not statistically significant, meaning there really wasn’t a difference. In live animals, mucocillary transport velocity in a normal airway did not change significantly with Vicks VapoRub exposure; on an inflamed airway there was a 34% increase with Vicks VapoRub exposure relative to controls. In either a normal or inflamed airway, there was no difference in lung fluid build up between control and Vicks VapoRub-exposed lungs.
These results do not demonstrate that Vicks VapoRub causes respiratory distress. This study principally shows two things. One: in an inflamed ferret airway, which is a model for human airway inflammation and mucus secretion, Vicks VapoRub exposure increases rather than decreases mucocillary transport velocity, the nonimmunological defense mechanism by which particulate matter is removed from the respiratory tract. Increased mucocillary transport velocity is a good thing. Two: direct contact of ferret tracheal tissue with Vicks VapoRub increases mucin secretion and decreases mucus clearance.
Thus, perhaps the most important take home message of this study: don’t swallow Vicks VapoRub.
NPR reports that a new study will test the effectiveness of Vicks VapoRub in 150 children . Those results should be much more applicable than the study described above, which has unknown human clinical significance. In the meantime, parents should continue to use Vicks VapoRub as directed; it should not be used on children under 2 or in the nostrils. If a rash or allergic reaction occurs, discontinue use immediately.
Note that Vicks VapoRub provides symptomatic relief and does not offer any medicinal value. Mentholated fumes activate cold-temperature receptors in the nose, giving the brain a sensation of increased airflow. Indeed, for some people, the cold sensation may trigger increased mucus production.
- Abanses et al. Vicks VapoRub induces mucin secretion, decreases ciliary beat frequency, and increases tracheal mucus transport in the ferret trachea. Chest. 2009 Jan;135(1):143-8. DOI: 10.1378/chest.08-0095
- Clearing Things Up: Vicks’ Effectiveness In Kids. National Public Radio (NPR). 2009 Jan 14.