Menthol (MEN-thol) occurs naturally in the peppermint
plant. In pure form it occurs as a white crystalline material
with a cooling taste and odor. Peppermint is one of
the oldest known herbal remedies. Dried peppermint
leaves have been found in Egyptian pyramids dating to
at least 1000 BCE, and its use among the Greeks and
Romans in cooking and medical preparations is well known.
Peppermint was not introduced to western Europe, however,
until the eighteenth century, when it was used to treat a
variety of ailments ranging from toothaches to morning
sickness. It was first brought to the United States about a
century later.
Peppermint oil is extracted from the leaves of the peppermint
plant, Mentha piperita, by steam distillation, by
which various oils in the plant are separated from each other.
The peppermint oil is then frozen to extract the menthol
from other components of the oil. Menthol can also be produced
synthetically by the reduction of thymol [(CH3)2CHC6H3
(CH3)OH] with hydrogen.
Menthol smells like mint and creates a soothing and
sometimes tingling sensation when it touches the skin.
Scientists theorize that menthol creates the cooling sensation
by triggering the same receptors on skin that tell the
body’s nerves to respond to cold temperatures.
The cooling sensation makes menthol a desirable additive
to aftershave lotions, skin cleansers, lotions, sore throat
lozenges, and lip balms. Menthol is also used in a variety of
cosmetics applied to the skin and medications for the relief
of itching. It is also added to foods such as chewing gums and
candies to impart a mint-like flavor.
When inhaled or ingested as a lozenge, menthol can relieve
nasal congestion and coughs, as well as cool and numb the
throat to ease the pain of sore throats. It can also be used in
ointments with camphor and eucalyptus to produce cooling and
antiseptic properties. These ointments can be applied to the
chest and/or nostrils to clear the nose and reduce coughing.
One of the most famous menthol-containing products is Vicks
VapoRub, which is used to relieve coughs and congestion.
Although menthol is soothing and cooling in small quantities,
it produces a quite different effect in larger quantities.
Gargling with a large amount ofmenthol-containing mouthwash,
for example, can create an unpleasant burning sensation.
Although menthol has been classified as a ‘‘generally
recognized as safe’’ (GRAS) product and approved for use in
foods by the U.S. Good and Drug Administration, some side
effects have been reported. On contact with the skin,
menthol may cause irritation. Ingesting large quantities can
cause abdominal pain, nausea, vomiting, dizziness, drowsiness,
and even coma. These effects are more likely to occur in
infants and children than in adults.
