1. Cooling effect
Menthol can exhibit good cooling effects at low concentrations (<2%), but as the concentration increases, the cooling effect gradually weakens and discomfort reactions gradually increase; When the concentration increases to 2% -5%, menthol exhibits stimulating and local anesthetic effects, and when the concentration reaches 5% -10%, there is a significant burning sensation.
Cooling mechanism: Irritating the cold receptors on the skin without causing actual temperature changes.
2. Promoting penetration
Studies have shown that menthol has a significant promoting effect on the transdermal absorption of both hydrophilic and lipophilic compounds, with a stronger effect on the latter, and the delay in the storage effect of both is significantly prolonged.
Menthol may act on lipids in the stratum corneum, causing changes in the structure or conformation of lipids, thereby altering the ordered and dense structure of the stratum corneum, causing the stratum corneum to detach, widening the gap between the stratum corneum, loosening the stratum corneum structure, and increasing skin permeability. This is the transdermal absorption promoting mechanism of menthol. (As shown in the figure, compared with the blank group, the menthol group showed a significant increase in epidermal folds, significant exfoliation of the stratum corneum, widening of inter epidermal cracks, and obvious loosening of the stratum corneum with pore like structures. In the longitudinal section, it was observed that the stratum corneum structure of the epidermis was significantly loose, with significant exfoliation of the outermost stratum corneum and clear gaps between the layers, resulting in separation between the epidermis and dermis.)
3. Soothing and itching relieving
Menthol can act on neurons that transmit itching sensation, inhibit the transmission of itching sensation, and induce a decrease in local temperature of itching, thus having a certain soothing and antipruritic effect.