Menthol and similar compounds feel cold because they switch on TRPM8, a nerve receptor that normally responds to falling temperature. Nothing in the mouth or on the skin actually cools down. The brain receives the same signal a cold drink would send and labels it as cold, while the tissue stays at body temperature.
What Does “Cold” Mean When Nothing Is Actually Cold?
Put a strong mint on your tongue, and the inside of your mouth feels several degrees cooler. Measure it with a thermometer and nothing has changed. The cold is a report from your nerves, and those nerves can be made to send that report without any drop in temperature.
The same chemistry runs through a long list of everyday products. Toothpaste, chewing gum, cough drops, lip balm, aftershave, muscle rubs, and flavored nicotine products such as flavored disposable vapes all use cooling compounds, and in every case the sensation comes from a molecule acting on a receptor rather than from anything physically cold.
Temperature sensing works through proteins sitting in the membranes of sensory nerve endings. Each one opens within a certain temperature range, letting charged particles into the nerve and starting a signal toward the brain. Some of those proteins also open when a particular molecule binds to them. That second route is the whole story behind chemical cooling, and its mirror image explains why chili peppers feel hot.
Which Receptor Makes Menthol Feel Cold?
The receptor is called TRPM8. Two research groups identified it independently in 2002: David Julius’s lab at the University of California, San Francisco, and Ardem Patapoutian’s lab at Scripps Research. Both showed that the same protein responds to cool temperatures and to menthol. Julius and Patapoutian shared the 2021 Nobel Prize in Physiology or Medicine for their work on temperature and touch receptors, and Julius had earlier identified TRPV1, the heat receptor that capsaicin from chili peppers switches on.
On its own, TRPM8 starts responding when tissue drops below roughly 26°C (about 79°F). Menthol changes that threshold. The process runs in four steps:
- A menthol molecule reaches a nerve ending in the mouth, nose, or skin.
- It binds to TRPM8 and shifts the temperature at which the channel opens, so the channel opens at normal body temperature.
- Calcium and sodium ions flow into the nerve, which fires the same signal it would send for a real drop in temperature.
- The brain reads that signal as cold, with no way of telling whether the cause was ice water or a molecule.
That last step accounts for most of what people describe as a fresh or clean sensation. The brain has long associated cool signals from the mouth and nose with cold water and moving air, so it files the chemical version under the same label.
Two details round out the picture. Repeated exposure dulls the receptor, which is why a strong mint fades after a few minutes even while some of it is still in the mouth. And at high concentrations, menthol also acts on irritant receptors, which is why very strong mint can sting or burn instead of cooling.
Why Do Menthol and Mint Not Feel the Same?
People use “mint” and “menthol” as if they meant the same thing, but they describe two separate parts of the experience. Menthol is a single compound that produces cooling. Mint is a flavor made of dozens of aroma compounds, and only some mint plants contain much menthol at all.
Peppermint oil is rich in menthol, which is why peppermint feels cold. Spearmint gets its scent mainly from a compound called carvone and contains very little menthol, so it smells unmistakably of mint while cooling far less. Cornmint (Mentha arvensis) is the richest natural source and supplies much of the world’s natural menthol.
A group of synthetic cooling agents cools without smelling of mint at all. The best-known came out of research at the razor maker Wilkinson Sword in the 1970s, which produced compounds still sold under the names WS-3 and WS-23. They let manufacturers add cold to fruit, cola, or berry flavors without turning them into mint. Eucalyptol, the main compound in eucalyptus oil, also acts on TRPM8, though more weakly than menthol.
The table below compares the most common sources of cooling and aroma.
| Compound | Where it comes from | Cooling strength | Mint aroma |
| Menthol | Peppermint and cornmint oil, or synthesized | Strong | Strong |
| Carvone | Spearmint and caraway | Mild at most | Strong (spearmint) |
| WS-3 | Synthetic, from Wilkinson Sword research | Strong | Faint |
| WS-23 | Synthetic, from Wilkinson Sword research | Moderate | Almost none |
| Eucalyptol | Eucalyptus oil, also bay leaf and rosemary | Mild | Camphor-like rather than mint |
Separating cooling from aroma is the reason a watermelon or blue raspberry product can feel icy without tasting like toothpaste.
Where Does the Cooling Effect Show Up in Consumer Products?
Oral care is the oldest and largest use. Toothpaste and mouthwash rely on menthol so heavily that many people treat the cold tingle as proof that their teeth are clean, even though the sensation has nothing to do with how much plaque was removed. Chewing gum and breath mints work the same way, and cough drops such as Halls pair menthol with eucalyptus oil.
Topical products use cooling on the skin. Muscle rubs such as Biofreeze and Bengay contain menthol, as do many lip balms, aftershaves, and foot creams. Vicks VapoRub combines menthol, camphor and eucalyptus oil, and its sharp cold feeling in the nose is one of the most familiar examples of chemical cooling.
Food and drink use it more quietly. Fresh mint leaves in a mojito or mint tea deliver both aroma and cooling, while ice cream, candy and some soft drinks lean on synthetic coolants to add a cold edge without a mint taste. Inhaled products, including nasal sticks and flavored e-liquids, use menthol or WS-23 to give the airway that same cool signal.
What Don’t Cooling Compounds Actually Do?
The most useful thing to know about chemical cooling is where it stops. Menthol does not lower the temperature of skin, mouth, or airway in any measurable way. Research led by Ron Eccles at Cardiff University’s Common Cold Centre found that menthol does not increase nasal airflow, even though people who inhale it consistently report that breathing feels easier. The cold receptors in the nose fire as if air were moving, and the brain reads that as an open airway.
Sensitivity also varies from person to person. Some people find a menthol product mildly cool while others find the same product harsh, and individual differences in receptor response are part of that gap.
The short version is that cooling is a signal rather than a temperature. TRPM8 cannot tell a cold drink from a menthol molecule, and the brain trusts the receptor.
