The Menthol Control for "Cooling Sensation" in Foot Creams: How to Avoid Over-Irritating Sensitive Skin?

After a long day of walking, applying foot cream at home brings an instant cooling sensation that penetrates the skin—almost the most memorable experience moment of this category.

But this "cooling" is a double-edged sword. If the concentration is too low, consumers feel "no sensation, not worth the price"; if it's too high, consumers report "stinging," "burning," and "uncomfortable fiery heat on the soles"—especially for sensitive skin groups and foot care scenarios with skin cracks or wounds, this risk is further amplified.

Today, from the perspectives of neurophysiology and formulation science, we will completely deconstruct: how the cooling sensation of menthol is actually produced, how the concentration should be precisely controlled, and what safer alternative and synergistic solutions exist in the industry in 2026.

I. The Truth Behind the Cooling Sensation: It's Not "Physical Cooling," but a "Neural Trick"

Many people think the cooling sensation brought by menthol is because it actually lowers the skin temperature. This is not the case.

The "cooling" effect produced by menthol is a physiological effect, originating from menthol directly acting on the nerve endings responsible for detecting cold and heat in the human body, rather than from the latent heat effect of evaporation. As a direct stimulant of cold receptor nerve endings, menthol subsequently stimulates the central nervous system.

More precisely, the cooling sensation of menthol is produced by binding to the TRPM8 receptor (the "cold and menthol-sensitive receptor"). After menthol binds to TRPM8, it generates an inward current in the sensory nerves, and this electrical signal is ultimately interpreted by the brain as the sensation of "cold."

The TRPM8 receptor itself is responsible for detecting temperature changes between 8°C and 28°C. Once activated, it triggers the influx of calcium and sodium ions, sending a cooling signal to the brain. In other words, menthol is "tricking" the nervous system, making the brain think the skin is getting cold, while the actual temperature of the skin has not undergone any substantive physical cooling.

Understanding this underlying mechanism is crucial because it directly explains why the relationship between menthol concentration and cooling intensity is not a simple linear one—and this is precisely the most easily misunderstood part in formulation design.

II. The Concentration Trap: "The More, The Cooler" is a Common Misconception

Many brand owners newly exposed to formulation design have an intuitive assumption: the more menthol added, the stronger the cooling sensation. Real scientific data, however, refutes this assumption.

A randomized controlled study tested menthol gels at three different concentrations: 0.5%, 4.6%, and 10.0%. The results showed that, contrary to the assumption, menthol concentration had no significant correlation with the actual cooling magnitude of the skin; instead, the medium concentration (4.6%) induced a stronger cooling sensation compared to the low (0.5%) or high (10.0%) concentration gels.

This finding is highly enlightening—concentration is not the higher, the better. There is an "optimal sensory range." Exceeding this range, continuing to increase the concentration yields diminishing returns in cooling enhancement, while the risks of irritation and side effects continue to accumulate.

Meanwhile, the negative effects brought by increased concentration are clear and continuously cumulative. A double-blind controlled study on athletes compared four menthol concentration gradients: 0.1%, 0.3%, 0.5%, and 0.7%. The results showed that the irritation scores of all menthol groups were higher than the control group without menthol, and the higher the concentration, the correspondingly higher the irritation score. The 0.7% and 0.5% concentration groups provided significantly stronger cooling sensations, but the accompanying irritation was also significantly higher.

Menthol has been used as a cooling substance for decades, but it has a series of inherent defects: it is volatile, has a strong odor, and tastes bitter. At higher concentrations, it no longer brings a pleasant cooling sensation, but instead produces stinging or burning sensations. Furthermore, the formulation application of menthol also has limitations because it may interact with other chemical components.

This means: for products like foot creams that need to stay on the skin surface for a long time and are frequently applied to skin that already has cracks or is in a sensitive state, the precise control of menthol concentration is a core issue of formulation safety, not just a simple "claim checkpoint."

III. Why is Foot Skin Extra Sensitive to Menthol?

The application scenarios of foot creams make the irritation risk of menthol more significant than in other skincare categories, for three reasons:

1. Special Skin Barrier State: The typical user group for foot creams often accompanies dry cracked heels, thickened stratum corneum, or localized skin damage. When the skin barrier is compromised, permeable active ingredients like menthol can more easily penetrate into the dermis, and the sensitivity of the receptors will also increase accordingly. A concentration that is "just right" on healthy skin could become "stinging and burning" on damaged skin.

2. Synergistic Effects with Other Active Ingredients: High-concentration urea and salicylic acid commonly found in foot creams themselves have a certain degree of keratolytic and mild irritating properties. If superimposed with a higher concentration of menthol, the irritating effects of multiple active ingredients will produce a synergistic amplification, rather than a simple linear addition.

3. Long-term Occlusive Environment (Wearing Shoes and Socks): After applying the product to the feet, consumers usually put on shoes and socks immediately, forming a relatively occlusive environment. This will prolong the contact time between the active ingredients and the skin, and may also affect the permeation behavior and irritation duration of menthol.

IV. The Formulator's Precise Control Strategies: Four Key Dimensions

After understanding the sources of risk, professional formulation design should precisely control the application of menthol from the following four dimensions:

Dimension 1: Lock in the "Optimal Sensory Range," Not Pursue the Highest Concentration

Based on existing scientific data, the medium concentration range (around 4%~5%) can often achieve a relatively ideal balance between cooling sensation and irritation. Blindly pursuing 10% or even higher concentrations yields significantly diminishing marginal benefits in terms of sensation, while the irritation risk continues to climb. This finding provides an important reference for menthol formulations in foot creams—formulators should lock their targets on the "optimal sensory range" rather than simply piling the concentration up to the upper limit allowed by regulations.

Dimension 2: Establish Tiered Product Lines for Sensitive Skin Populations

Considering the huge differences in menthol tolerance among different consumers, it is recommended that brand owners consider establishing a cooling sensation grading system during the product line planning phase—for example, launching a "Standard Cooling Version" (moderate menthol concentration, suitable for ordinary consumers) and a "Mild Non-Irritating Version" (lower menthol concentration or using alternative cooling agents, specifically targeting sensitive skin, compromised skin barriers, or usage scenarios with wound risks). This tiering strategy can satisfy consumers pursuing a strong cooling experience while also catering to those sensitive to menthol, expanding the product's reachable user base.

Dimension 3: Introduce Milder TRPM8 Activation Alternative Ingredients

Besides menthol, various synthetic cooling agents can also activate the TRPM8 receptor, including Cool-act P, Cooling Agent 10, Frescolat MGA, Frescolat ML, as well as WS-3 and WS-23. Among these synthetic cooling agents, some varieties have significantly lower irritation than natural menthol.

Taking WS-23 as an example, WS-23 activates TRPM8 in a way that favors rapid but controllable receptor stimulation. Unlike menthol, which embeds into the cell membrane and prolongs the effect, WS-23 has a lower tendency for bioaccumulation in lipid-rich tissues. WS-23 can enhance the cooling sensation without producing stinging or burning, bringing a smoother, more evenly distributed cooling experience. Menthol directly binds to TRPM8 and prolongs the activation state, while the action mode of WS-23 brings a cooling effect that takes effect quickly, reaches its peak rapidly, and dissipates more evenly. Unlike menthol, which produces intense stimulation concentrated at specific contact points, it generates a more diffuse cooling experience.

This means that for product lines hoping to retain the cooling sensation while reducing the risk of irritation, compounding menthol with synthetic cooling agents like WS-23 is a formulation direction worth exploring. It can maintain the "cooling sensory signal" expected by consumers while reducing the cumulative irritation risk brought by high concentrations of a single ingredient by adjusting the ratio of different cooling agents.

Dimension 4: Pair with Soothing Ingredients for Risk Hedging

Drawing on the synergistic logic of "urea + soothing ingredients" in foot cream formulations, cooling foot creams containing menthol should also be configured with soothing ingredients for risk hedging. Ingredients like panthenol (provitamin B5), prebiotics, and probiotic lysates have been clinically verified to effectively improve sensitive skin symptoms and exert soothing effects by supporting skin barrier function. Adding classic soothing ingredients like panthenol, Centella Asiatica extract, and chamomile to menthol-containing foot cream formulations can buffer the potential irritation reaction while menthol exerts its cooling efficacy.

V. Pre-launch Verification: How to Scientifically Test "Cooling but Not Irritating"?

Verbally claiming "mild cooling" is not enough; a professional OEM should possess the corresponding testing and verification capabilities:

1. Human Sensory Evaluation Test: Referencing mature clinical research methods, use a standardized 100-point Labeled Magnitude Scale to quantitatively score the intensity of cooling sensation, intensity of irritation, aroma experience, and overall experience, ensuring the formulation reaches the target balance point between cooling and irritation, rather than relying solely on the subjective judgment of R&D personnel.

2. Skin Tolerance Test: Conduct closed patch testing before the product launches, specifically targeting test scenarios simulating slight skin damage on the heels, to verify the safety boundary of menthol concentration in the special usage environment of the feet.

3. Thermal Imaging Verification: Use digital infrared thermal imaging equipment to record changes in skin surface temperature, which can objectively quantify the actual cooling effect of the product and cross-validate it with subjective cooling sensation scores, avoiding the two deviations of "claiming cooling but actually ineffective" or "actually effective but claiming exaggeratedly."

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By collaborating with Deva Skincare, you gain access to industry-leading expertise and innovative formulations that set your brand apart in the competitive global market. Contact us today to discover how we can help you succeed.

Final Thoughts: Cooling Sensation is a Science of "Just Right"

"Cooling sensation" sounds like a simple and direct product experience demand, but behind it lies the neurophysiological mechanism of TRPM8 receptors, the non-linear scientific relationship between concentration and sensation, and the essential differences in the modes of action between synthetic cooling agents and natural menthol.

Truly responsible formulation design is never about "adding to the highest concentration allowed by regulations," but understanding the mechanism of action of every cooling agent, and finding that precise balance point between "letting consumers feel a pleasant cooling sensation" and "not making any consumer feel stinging or discomfort because of it."

If you are developing a foot care product headlined by the cooling experience, we welcome you to communicate with our R&D team. We possess mature compounding experience with cooling agents and skin tolerance testing capabilities, able to help you create a product that is truly "refreshingly cooling without irritating sensitive skin."