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

1. British National Formulary (BNF), LEVOMENTHOL, https://bnf.nice.org.uk/medicinal-forms/levomenthol.html, (last accessed 9th May 2022)
2. National Institute for Health and Care Excellence, Topical local antipruritics, http://bnf.nice.org.uk/treatment-summary/topical-local-antipruritics.html (last
accessed 9th May 2022)
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 9th May 2022)
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.