Page 3 - Menthoderm 4pp MEN241-0224

The Benefits of Menthol 3

Menthol is natural cyclic terpene alcohol from plant
origin and has been used since antiquity for medicinal
purposes. Today Menthol can be found in both prescription
and OTC medications for a range of different conditions. It
is also used in Dermatology where it is frequently
prescribed for its antipruritic properties.
MENTHOL - THE MECHANISM OF ACTION
Despite its widespread use the mechanism by which
Menthol is able to impart a cooling sensation when applied
topically to the skin remained a mystery until early 2002.
Two independent studies by McKemy et al and Peier et al
identified a 1104 amino acid cation channel receptor - Furthermore, the authors
TRPM8. This receptor, cloned and characterized, could be suggested that this effect provided a molecular basis for
activated by both Menthol and a thermal stimuli in the cool the antinociceptive and local anaesthetic properties of
to cold range 8 - 28C. This proves that Menthol acts as an this compound.
agonist for a thermally sensitive receptor. Psychophysical CONCLUSION
studies have also shown that menthol evokes a cool
sensation to the skin or mucous membrane. Menthol is widely used in the UK, especially dermatology,
where it is frequently part of topical antipruritic, analgesic,
ANTIPRURITIC BENEFITS OF antiseptic, and cooling preparations, such as Menthol in a
TOPICAL MENTHOL topical cream base. It has an excellent safety and toxicity
The precise mechanism by which menthol alleviates profile. As highlighted by Patel et al the recent discovery
pruritus is unknown and the optimal concentration of of the TRPM8 receptor finally provides the answer to how
menthol for the relief of pruritus has yet to be fully menthol can elicit the same cool sensation as low
established. Different opioid receptors have contrasting temperatures.
effects upon pruritus. Menthol has been shown to
selectively activate k-opioid receptors, and Patel et al UNDECYLENIC ACID
postulated that this mechanism may also possibly explain Is an organic compound often derived from Castor Oil
the antipruritic properties of this compound. He also noted (ricinoleic acid). It is produced by “cracking” Castor oil
that patients who suffer from chronic pruritic conditions, under pressure and, in higher strengths can be used as a
such as atopic dermatitis, uremic pruritus and psoriasis powerful antifungal agent for a variety of pathogenic fungi.
report an apparent itch reduction by taking a cold shower. Primarily undecylenic acid is the active ingredient in many
Therefore, it is possible that the cooling sensation menthol medications for skin infections, which relieves itching,
imparts to the skin serves as a possible mechanism to burning, and irritation. For example, it is used against
reduce itch perception in certain patients. fungal skin infections, such as athlete’s foot, ringworm.
LOCAL ANAESTHETIC ACTIVITY OF SAFETY/TOXICITY
TOPICAL MENTHOL Relatively small doses of undecylenic acid and its salts
In a recent study, Haeseler et al concluded that menthol have been shown to have powerful antifungal properties,
blocks voltage-gated neuronal and skeletal muscle and the dosages necessary to achieve therapeutic benefit
sodium channels in a concentration-dependent manner in appear to be safe.
resting and inactivated states.

1. British National Formulary (BNF), LEVOMENTHOL, https://bnf.nice.org.uk/medicinal-forms/levomenthol.html, (last accessed 15th January 2024)
2. National Institute for Health and Care Excellence, Topical local antipruritics, http://bnf.nice.org.uk/treatment-summary/topical-local-antipruritics.html (last accessed 15th January
2024)
3. National Health Service (NHS), Itching and intrahepatic cholestasis of pregnancy, https://www.nhs.uk/pregnancy/related-conditions/complications/itching-and-intrahepatic-
cholestasis/ (last accessed 15th January 2024)
4. Patel et al., ‘Menthol: A refreshing look at this ancient compound’ Journal of the American Academy of Dermatology, vol. 57, no 5, 2007, pp. 873-878.
.