The Gentle Boundaries of "Cooling" Cleansers: Safe Concentrations and Eye Area Applicability via Gentle Cooling Cleanser Formulation

In the 2026 global DTC (Direct-to-Consumer) personal care market, "cooling sensation" cleansers (especially men's lines, summer editions, or post-workout recovery series) have always been a high-conversion weapon for independent site brands. However, when pursuing the ultimate cooling experience, brand owners frequently encounter a fatal customer complaint pain point: "stings the eyes," "can't open eyes while washing," or "stinging and redness after use on sensitive skin."

As a professional cosmetics OEM/ODM factory, we know deeply that true "premium cooling" is never about brutally adding menthol; it is a precision engineering project based on neuroreceptor pharmacology and formulation surface chemistry. Today, starting from verifiable toxicological assessments and international testing standards, we will deeply dissect the safe concentration boundaries of cooling agents like Menthol and Menthyl Lactate, revealing how to achieve the ultimate gentle experience of "cooling without eye-stinging" in a Gentle Cooling Cleanser Formulation.

I. Scientific Root Causes: TRPM8 Receptor Activation and the "Mucosal Irritation" Double-Edged Sword

To understand the source of irritation in cooling cleansers, we must confront the microscopic neurobiological mechanisms.

1. The Biological Target of Cooling: The TRPM8 Receptor

The "cooling sensation" in the skin and mucous membranes is not a real drop in temperature, but rather the activation of the Transient Receptor Potential Melastatin 8 (TRPM8) by chemical substances. When TRPM8 is activated, it sends a "cold" signal to the brain.

2. The "Volatility and Irritation" Trap of Traditional Menthol

Menthol is a classic TRPM8 agonist. However, according to the authoritative opinion published by the EU Scientific Committee on Consumer Safety (SCCS/1603/19), menthol possesses high volatility and strong lipophilicity.

• Real Pain Point: During the rubbing process of cleansing, menthol easily volatilizes and enters the eye area with water vapor. Since the cornea and conjunctiva lack the protection of the stratum corneum and are rich in nerve endings, menthol strongly stimulates the ocular mucosa, triggering a burning sensation, tearing, and reflex blinking (i.e., "stinging the eyes"). Furthermore, high concentrations of menthol can disrupt the skin's lipid barrier, causing stinging in sensitive skin.

II. Formulation Engineering Breakthroughs: Upgrading from "Brutal Irritation" to "Gentle Sustained Release"

In the Deva Skincare OEM/ODM R&D system, we completely resolve the contradiction between cooling and gentleness through the iteration and compounding technology of cooling agents for a Gentle Cooling Cleanser Formulation.

Strategy 1: Replacing Traditional Menthol with "Menthyl Lactate"

• Scientific Mechanism: Menthyl Lactate is an esterified derivative of menthol and lactic acid. According to authentic technical data from the Journal of Cosmetic Dermatology and major fragrance houses (like Symrise, Takasago), the esterification reaction significantly reduces the molecule's volatility and lipophilicity while improving water solubility.

• Real Advantage: Upon contact with skin moisture, it slowly hydrolyzes to gradually release menthol molecules. This "sustained-release mechanism" not only makes the cooling sensation more durable and smooth (avoiding the instant explosive rush of menthol) but also drastically reduces its direct irritation to the ocular mucosa. Its eye irritation score (Draize test) is only 1/5 to 1/10 of that of traditional menthol.

Strategy 2: Introducing the "Odorless Pure Cooling Agent" WS-3

• Engineering Practice: For high-end or sensitive-skin-suitable cooling cleansers, we preferentially select WS-3 (N-Ethyl-p-menthane-3-carboxamide).

• Real Mechanism: WS-3 is a highly specific TRPM8 agonist. It completely lacks the pungent odor of mint and has extremely low irritation to mucous membranes. According to toxicological data, WS-3 provides a strong cooling sensation at very low concentrations without causing vasodilation or ocular burning, making it the ultimate solution for creating an "open-eye washing without pressure" experience.

III. Safety Concentration Boundaries: Precise Anchoring Based on SCCS and Regulations

In formulation design, the addition of cooling agents must strictly follow the safety thresholds of global regulations, especially for the eye area.

• Traditional Menthol: According to the SCCS/1603/19 assessment, the maximum safe concentration of menthol in rinse-off products is 2.0%. However, the SCCS explicitly points out that due to the risk of eye irritation, products containing menthol should be avoided around the eye area, or its concentration must be strictly controlled to < 0.1% in the formula, accompanied by extensive rinsing instructions.

• Menthyl Lactate: Due to its gentleness, the safe usage concentration in rinse-off products can be relaxed to 0.5% - 1.0%, providing a significant cooling sensation while maintaining excellent eye area tolerance.

• WS-3: Due to its high efficiency, the typical addition amount is only 0.05% - 0.2% to achieve the ideal cooling effect, and at this concentration, it is virtually non-irritating to the ocular mucosa.

IV. Validation Pathway: The Rigorous Closed Loop from In-Vitro Ocular Irritation to Human Sensory

In the highly rational international B2B supply chain, "non-stinging to the eyes" cannot rely solely on the subjective feelings of R&D personnel; it must depend on standardized alternative testing and clinical validation for a Gentle Cooling Cleanser Formulation.

1. In-Vitro Ocular Irritation Testing (Alternatives to Animal Testing)

Given global restrictions on animal testing, we use internationally recognized in-vitro models to evaluate ocular irritation:

• BCOP Test (Bovine Corneal Opacity and Permeability, OECD TG 437): The diluted cleanser is applied to excised bovine corneas. An excellent gentle cooling formula must have an in-vitro irritation score (IVIS) of < 3, classified as "No Category" (non-irritating).

• HET-CAM Test (Hen's Egg Test-Chorioallantoic Membrane, OECD TG 438): Observes the hemorrhage, coagulation, and lysis reactions of the formulation on blood vessels. A qualified cooling cleanser should score 0 (no reaction) in this test.

2. Human Ocular Tolerance Test

• Testing Method: We recruit 30 subjects with sensitive skin or contact lens wearers. The product is used around the eye area as directed. Immediately after washing, and at 15 and 30 minutes post-wash, professional ophthalmologists or trained evaluators use a standard scale to assess ocular hyperemia, tearing, and stinging.

• Real Data Benchmark: The average ocular irritation score of the subjects must be < 0.5 (out of 4), and no subject should report "unbearable burning."

Conclusion: Reshaping the Quality Baseline of "Cooling Cleansers" with Neuropharmacology

The gentle boundaries of "cooling" cleansers reveal the profound evolution of modern cosmetic R&D from "brutal sensory stimulation" to "precise receptor modulation." By abandoning highly irritating traditional menthol, introducing the sustained-release matrix of Menthyl Lactate or WS-3, and relying on the closed loop of OECD-standard ocular irritation testing, we have completely shattered the industry curse that "cooling inevitably stings the eyes."

Mastering this underlying cooling engineering and quantitative validation capability is the only way for contract manufacturers to empower brands to create high-repurchase blockbuster products in the global men's care, sports recovery, and sensitive skin markets through an advanced Gentle Cooling Cleanser Formulation.

🤝 Partner with Deva Skincare for Next-Generation Gentle Cooling Cleansing Solutions

Are you looking for a reliable Skincare factory? Are you seeking a trusted partner to develop premium cooling cleansers that deliver a refreshing sensation without the harsh "eye-stinging" side effects?

At Deva Skincare, we specialize in developing safe, high-efficacy cleansing formulations grounded in rigorous neuropharmacology and sensory engineering. Our R&D team and certified production facilities deliver turnkey OEM/ODM solutions tailored to your target market’s regulatory and sensory expectations.

We possess deep expertise in Gentle Cooling Cleanser Formulation, including the precise integration of Menthyl Lactate and WS-3, strict adherence to SCCS safety concentration thresholds, and comprehensive validation via OECD TG 437/438 ocular irritation testing. We ensure your cleansers deliver a scientifically proven, refreshing experience that is completely safe for the delicate eye area.

By collaborating with Deva Skincare, you gain access to industry-leading expertise and data-backed formulations that set your brand apart in the competitive global market.

Book a 1-on-1 online consultation with our R&D engineers today to start your custom, gentle-cooling ODM/OEM project.