Menthol
Evidence: limited
Menthol activates cold receptors in the mouth and skin, so it reliably makes hot running feel cooler without changing core temperature, sweat rate or heart rate. A genuine performance benefit is smaller and less certain: non-significant when pooled across trials, and clearest in dry heat, still air and sustained efforts.
Not medical advice
This is a general knowledge base, not medical or dietary advice. If you are injured, unwell or weighing up a supplement or a change to your diet, speak to a doctor, physiotherapist or registered dietitian who knows your situation.
Menthol is the cooling compound in mint. It works on the thermoregulatory system by trickery, not physics: it binds the TRPM8 cold receptor, the same channel that fires in genuine cold, so the brain reads a coolness signal that the skin temperature has not actually changed. Runners use it three ways — as a dilute mouth rinse, ingested in a drink, or applied to the skin or clothing — mostly to make hot conditions more bearable.
What it reliably does: feel cooler
The perceptual effect is the well-established part. Pooling 17 randomised trials in 177 athletes, menthol lowered rated thermal sensation by a weighted mean of −1.65 on the scale (95% CI −2.96 to −0.33), and the effect was larger in still air than with a breeze (Keringer et al. 2020). That fits the mechanism: menthol adds a cooling sensation where moving air would otherwise supply real evaporative cooling.
What it does not do is cool the body. Across the same trials there was no meaningful change in core temperature (+0.02 °C), sweat production or heart rate (Keringer et al. 2020). Menthol changes the reading on the dial, not the heat load behind it.
The performance evidence is thinner
Whether feeling cooler makes you run faster is the weaker claim. A meta-analysis of menthol mouth rinsing across 10 studies found no significant overall effect on capacity or performance (SMD 0.12; 95% CI −0.08 to 0.31), with the endurance-specific estimate slightly larger but still not significant, and a high risk of bias from trials that skipped familiarisation and proper blinding (Gavel et al. 2024). A 2026 network meta-analysis comparing delivery routes reached the same place: ingestion ranked highest and mouth rinse lowest for endurance, but every route’s effect was modest and non-significant, and the authors graded the evidence low-to-very-low certainty (Zhu et al. 2026).
The cleanest positive result in running is a single trial. Eleven trained men ran 5-km treadmill time-trials at 33 °C: a 0.01% menthol mouth rinse improved their times (P = 0.01), whereas ice-slurry ingestion lowered core temperature but did not improve performance (Stevens et al. 2016). That contrast — a perceptual cue helping while a real internal cooling method did not — is the strongest hint that in the heat, how hot a runner feels can matter as much as their actual core temperature.
Where a signal does appear
The subgroup pattern is consistent enough to act on. A performance benefit is likeliest in:
- Dry heat. Below about 50% relative humidity menthol showed a robust ergogenic signal; at higher humidity it was markedly attenuated (Zhu et al. 2026). This mirrors why humidity dominates heat stress: in humid air evaporation is already choked, and a coolness illusion does little to help.
- Still air and warmer conditions. Time-to-exhaustion benefits concentrated in warmer environments (>31 °C) and where airflow was low (Keringer et al. 2020).
- Sustained, fixed-intensity efforts more than short time-trials (Keringer et al. 2020).
The catch: it decouples feeling from strain
A cooling sensation is not cooling
Because menthol blunts perceived heat strain without reducing the real thing, it can flatter a dangerous situation — a runner feels more comfortable while core temperature climbs exactly as it would have (Zhu et al. 2026). Treat it as a comfort aid, never a substitute for genuine cooling, hydration or heeding the warning signs of heat illness.
For this reason menthol is best seen as a perceptual tool that makes hot running more tolerable, with a possible small performance bonus in dry, still heat, rather than a cooling strategy. The proven ways to run better in the heat are physiological, not perceptual: heat acclimation, sensible pacing and real cooling before and during the effort.
Practical use
Studies typically use a dilute mouth rinse — around 0.01% menthol solution, swilled and spat, not swallowed (Stevens et al. 2016) — or a menthol spray or gel on the skin and clothing. It is cheap and low-risk, and the pooled trials found no compromise of the body’s protective heat responses (Keringer et al. 2020). If you try it, rehearse it in training rather than debuting it on race day, and keep it as an addition to a real heat plan, not a replacement for one.