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 or nostrils [but see Adverse Effects […]).
However, as mentioned under the section on the management of cough […], the use of menthol in inhalations is unlikely to provide any additional benefit.
When applied to the skin menthol dilates the blood vessels causing a sensatin of coldness followed by an analgesic effect. It relieves itching and is used in creams, lotions, or ointments in pruritus and urticaria. It has also been applied to the forehead, presumably as a counter-irritant, for the relief of headache.
In small doses by mouth menthol has a carminative action.
Adverse Effects
Menthol may give rise to hypersensitivity reactions including contact dermatitis. Ingestion of significant quantities of menthol is reported to cause symptoms similar to those seen afther ingestino of champhor […], including severe abdominal pain, nausea, vomiting, vertigo, ataxia, drowsiness, and coma; they may be managed similarly. There have been reports […] of apnoea and instant collapse in infants after the local application of menthol to their nostrils.