The effects of D and L isomers of menthol upon nasal sensation of airflow.

Objective and subjective measurements of nasal airflow were made before and after inhalation of Vanilla, D-Menthol and L-Menthol separately. Despite the fact that the menthol isomers were mirror images of one another, only L-Menthol produced the sensation of increased nasal airway patency. No objective change in resistance was found after inhaling either D-Menthol, L-Menthol or the vanilla control. These findings demonstrate that L-Menthol exerts a specific action upon nasal sensory nerve endings, which are responsible for the subjective appreciation of nasal airflow.