Menthol
Properties
At room temperature menthol is a clear or white, waxy, crystalline solid, and it melts slightly above room temperature. Its molecule exists in several mirror-image forms, and the main form found in nature is (−)-menthol.[2] Both (−)- and (+)-menthol smell of peppermint, but (−)-menthol cools much more strongly.[3]
How it is obtained
Natural menthol comes from mint oils, which are first obtained from the plants by steam distillation. Menthol makes up about 70 to 80% of the oil of cornmint, Mentha arvensis.[1] In peppermint oil it is usually 30 to 55%.[4]
To separate the menthol, the mint oil is cooled: at low temperatures menthol settles out of the oil as a crystalline powder. The remaining "dementholised" oil is sold as a cheaper substitute for mint oil.[1]
Menthol can also be made synthetically, for example from thymol by hydrogenation (adding hydrogen). Synthetic (−)-menthol is sold with a purity of 99.9%.[2]
The cooling effect
Menthol makes the skin feel cool when it is applied, inhaled or swallowed, without actually lowering the skin temperature. It does this mainly by activating the cold-sensitive receptors in the skin known as TRPM8.[2]
Uses
Menthol is used as a flavour or fragrance in liqueurs, sweets, perfumes, cigarettes, cough drops and nasal inhalers, and also in chewing gum and chest rubs. Medicines containing it, such as cough drops, are intended to relieve minor throat irritation.[2]
Safety
- On the skin menthol is a mild irritant, but it can damage the mucous membranes, the moist linings of the body, more severely.[2]
- Menthol should not be inhaled by an infant or small child or put on their face, because it may affect their breathing.[5]
- Mentholated nose drops used in infants have caused isolated cases of a spasm of the larynx (voice box).[2]
Menthol is classed as a fragrance allergen.[2] In one 2010 study, 1 of 1,147 patients patch-tested with 1% menthol had a weak positive reaction. Case reports describe rhinitis and asthma caused by menthol-containing products such as toothpaste and sweets.[6]
EU cosmetics rules require menthol to appear in a cosmetic's ingredient list above a set level. The level is 0.001% for products left on the skin and 0.01% for products that are rinsed off.[7]
Products containing it
- Body Cream With Eucalyptus Madeira (I 143)
- Deodorant Cream, Eucalyptus Nun's Valley Madeira (I 145)
- Mama Mia Aromatic Spray, Viva Plus (E 118)
- Massage Oil, Eucalyptus Nun's Valley Madeira (I 141)
- Shower Gel, Eucalyptus Nun's Valley Madeira (I 142)
Sources
- ↑ 1.0 1.1 1.2 1.3 Ayesha Mushtaq et al., Development of Methodology for molecular crystallization of Menthol. Heliyon 10 (2024), e38394, doi 10.1016/j.heliyon.2024.e38394.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 National Library of Medicine, PubChem: (−)-Menthol, CID 16666. Retrieved 17 October 2026.
- ↑ Jugreet B. Sharmeen et al., Essential Oils as Natural Sources of Fragrance Compounds for Cosmetics and Cosmeceuticals. Molecules 26 (2021), 666.
- ↑ European Medicines Agency, Committee on Herbal Medicinal Products, Assessment report on Mentha x piperita L., folium and aetheroleum, EMA/HMPC/522409/2013, Revision 1, 15 January 2020.
- ↑ National Center for Complementary and Integrative Health, Peppermint Oil. Retrieved 8 November 2026.
- ↑ Scientific Committee on Consumer Safety (SCCS), Opinion on fragrance allergens in cosmetic products, SCCS/1459/11, adopted 26–27 June 2012.
- ↑ European Commission, CosIng, Annex III: list of substances which cosmetic products must not contain except subject to the restrictions laid down. Retrieved 9 November 2026.