Background: Vicks VapoRub (VVR) [Proctor and Gamble; Cincinnati, OH] is often used to relieve symptoms of chest congestion. We cared for a toddler in whom severe respiratory distress developed after VVR was applied directly under her nose. We hypothesized that VVR induced inflammation and adversely affected mucociliary function, and tested this hypothesis in an animal model of airway inflammation.
Methods:  Trachea specimens excised from 15 healthy ferrets were incubated in culture plates lined with 200 mg of VVR, and the mucin secretion was compared to those from controls without VVR. Tracheal mucociliary transport velocity (MCTV) was measured by timing the movement of 4 microL of mucus across the trachea. Ciliary beat frequency (CBF) was measured using video microscopy.  Anesthetized and intubated ferrets inhaled a placebo or VVR that was placed at the proximal end of the endotracheal tube. We evaluated both healthy ferrets and animals in which we first induced tracheal inflammation with bacterial endotoxin (a lipopolysaccharide [LPS]). Mucin secretion was measured using an enzyme-linked lectin assay, and lung water was measured by wet/dry weight ratios.
Results:  Mucin secretion was increased by 63% over the controls in the VVR in vitro group (p < 0.01). CBF was decreased by 35% (p < 0.05) in the VVR group.  Neither LPS nor VVR increased lung water, but LPS decreased MCTV in both normal airways (31%) and VVR-exposed airways (30%; p = 0.03), and VVR increased MCTV by 34% in LPS-inflamed airways (p = 0.002).
Conclusions: VVR stimulates mucin secretion and MCTV in the LPS-inflamed ferret airway. This set of findings is similar to the acute inflammatory stimulation observed with exposure to irritants, and may lead to mucus obstruction of small airways and increased nasal resistance.