A new paper in the journal CHEST presents the case of a toddler who went into respiratory distress after receiving a smear of Vicks VapoRub under her nose. To figure out what happened, the researchers replicated the treatment in ferrets, whose respiratory systems are a good model for humans. The results were not exactly consistent with the Vicks “Breathe free” slogan:

[VapoRub] stimulates mucin secretion and [mucociliary transport] in the … 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.