Menthol gel applied to skin reduces skin and intramuscular temperature like ice, but effects last longer than ice
Cryotherapy, the application of cold as therapy, has been an effective pain reliever for years. While ice packs are most commonly applied to injured areas, topical menthol gels have been used successfully as well. When compared to ice, topical menthol such as Biofreeze has been shown to reduce neck pain more effectively.
Although the specific mechanism of action for topical menthol’s analgesic effect remains unclear, the counterirritant action of menthol and evaporation have been proposed mechanisms for the pain relief and cooling sensation.
Topical menthol has also been shown to change blood flow somewhat paradoxically: menthol increases cutaneous (superficial skin) blood flow, while decreasing arterial blood flow. It’s thought that the skin blood flow increases as a result of stimulation of cold receptors in the skin vasculature (TRPM8 receptors, which cause vasodilation), while arterial blood flow decreases as a systemic response to the cooling sensation. Arterial blood flow to the contralateral limb is also reduced after applying topical menthol, supporting a systemic response to superficial cooling.
Researchers in Scotland tested the blood flow and tissue temperature effects of topically-applied menthol gel, a placebo gel, and ice. They published their results in the International Journal of Sports Physical Therapy. In this cross-over design, 20 healthy males were tested on separate days with random assignment of each condition applied to one anterior thigh. They measured skin, core, and intramuscular temperature as well as cutaneous and arterial blood flow.
The menthol gel significantly increased cutaneous blood flow and reduced intramuscular and skin temperature. Menthol produced a cooling sensation longer than ice or placebo gel, lasting 80 minutes. All 3 conditions significantly decreased arterial blood flow (both ipsilaterally and contralaterally) while core temperature remained the same. Interestingly, the placebo gel also significantly reduced intramuscular temperature but did not change cutaneous blood flow.
Because the placebo gel also reduced skin and intramuscular temperatures, the researchers suggested that the mechanism of action for intramuscular cooling was likely evaporation, “rather than from any pharmacological action of the menthol.” Furthermore, intramuscular temperature remained reduced for 80 minutes after gel application, suggesting “greater sustained cooling effect than ice,” offering a more practical cooling solution when an ice pack may be impractical.
While this study confirmed the results of previous Biofreeze studies on cutaneous and arterial blood flow, this was the first study to show that topical menthol gel can reduce intramuscular temperature, which may be desirable after a soft-tissue injury or intense exercise. The study also suggests that topical menthol may be an effective alternative for ice, although more research is needed.
Reference
Hunter AM, Grigson C, Wade A. Influence of topically applied menthol cooling gel on soft tissue thermodynamics and arterial and cutaneous blood flow at rest. Int J Sports Phys Ther. 2018 Jun;13(3):483-492.
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