Menthol (kristallijn of naalden) is hoofdzakelijk bedoeld voor uitwendig gebruik.
Martindale beschrijft:
Uses and administration
Menthol is chiefly used to relieve symptoms of bronchitis, sinusitis, and similar conditions. For this purpose it may be used as an inhalation, usually with benzoin or eucalyptus oil, as pastilles, or as an ointment with camphor and eucalyptus oil for application to the chest …