Sensitive skin refers to skin hyperreactivity that occurs under certain physiological or pathological conditions and primarily affects facial skin. When stimulated by chemical and mental factors, sensitive skin will manifest as a burning sensation, stinging pain, itching, and tightness, which are accompanied or unaccompanied by objective signs, such as erythema, skin scaliness, and capillary dilation.
The causes of sensitive skin are multifactorial, encompassing intrinsic factors and external environmental influences. Intrinsic factors include differences in genetic background, age, and gender. Sensitive skin is a common skin condition that is highly prevalent worldwide. Women are more prone to experiencing sensitive skin conditions than men.
The decrease in the prevalence of sensitive skin with aging may be attributed to an overall reduction in susceptibility to skin irritation, as well as a diminished capacity for displaying visible signs of dermatological irritation. Irregular lifestyles, frequent consumption of spicy food, and stress in life and work are common features of young individuals with sensitive skin. In addition, a lack of skincare habits and misuse of household chemicals will further aggravate stress in the skin and trigger young people’s sensitive skin responses.
External environmental factors include seasonal changes, climatic fluctuations (e.g., temperature fluctuations), and other natural conditions. Chemical substances, such as cosmetics, fragrances, and hair dyes used in everyday life; disinfectants; and air pollutants in the environment, are also key influencing factors of skin sensitivity. Sensitive skin may be secondary to certain skin diseases, such as atopic eczema, acne, contact dermatitis, and eczema
The skin barrier is a natural protective membrane. Normal skin-barrier function is critical for maintaining physiological skin functions. Besides blocking the invasion of harmful chemical, physical, or biological factors from the external environment, the skin barrier can also prevent the loss of nutrients, water, and electrolytes. In sensitive skin, reduced ceramide content is common because of impaired stratum corneum integrity and imbalanced lipid content in epidermal cells. A reduction in ceramide content damages the skin barrier, increasing water loss and weakening the defence capacity of the skin against bacteria.
In sensitive skin, the weakened protective capacity of nerve endings, decreased density of nerve fibres and heightened reactivity of sensory nerves result in the dysfunction of sensory nerves. Weakening the protective capacity of nerve endings renders sensitive skin more susceptible to influences by external stimuli. The dysfunction of sensory nerves in the skin is usually closely associated with the transient receptor potential vanilloid (TRPV) family. TRPV is a multimodally activated, calcium-permeable, non-selective cationic channel that transmits sensitivity-related sensory symptoms.
Immune cells (e.g., mast cells, macrophages, and lymphocytes) are abundant in the epidermal and dermal skin layers and primary participants in skin inflammatory responses [13]. These cells, closely associated with the pathogenesis of sensitive skin, play an important role in the skin’s defences against external stimuli and maintain skin homeostasis.
Oils have long been used in the care and medical treatment of the skin because of their ability to protect the skin barrier through blocking effects, which enable the preservation of the skin’s water content. Hyaluronic acid (HA) is a non-species-specific acidic mucopolysaccharide that is prevalent in the skin and the intercellular matrices of muscles, bones, and tissues. Aloe vera is a widely recognised medicinal plant with vast applications in treating various skin diseases. Aloe vera leaf gel has been investigated in many in vitro, in vivo, and clinical studies. Indian chrysanthemum (Chrysanthemum indicum) also possesses skin-barrier-protecting and repair-promoting functions. Centella asiatica extract (CAE) significantly reduces the levels of human claudin 1 and human tight junction protein 1. Furthermore, through network pharmacology predictions, CAE is suggested to potentially improve skin-barrier damage.
In recent years, peptides have become a focal topic of research in developing active substances with skin-soothing as well various citrus fruit extracts.
Medications to treat skin inflammation include steroidal and non-steroidal anti-inflammatory drugs. Although both types provide extremely strong anti-inflammatory and pain alleviation effects, they produce significant side effects and may damage human organs. In recent years, natural plants have been widely applied to treat skin inflammation, as they slow skin disease development, control inflammation, and have a good safety profile and milder side effects. Developing safe and effective anti-inflammatory medications from natural plants is a focal research topic.
Additionally, numerous active substances have been verified for their anti-inflammatory properties through human trials looking at the number of non-inflammatory and inflammatory acne lesions, red/melanin pigmentation levels, and collagen density. Examples include madecassoside, Aescus chinensis extract, Castanea sativa shell extract, Aloe barbadensis extract, Ginkgo biloba leaf extract, Sphaeranthus indicus polyphenols, Punica granatum seed oil extract, and Actinidia arguta leaf extract.
Sensitive skin is a syndrome that can be classified into primary and secondary types. Its formation mechanisms are complex and multifactorial, and the treatment of the condition is usually difficult. Numerous active substances have been developed to target different mechanisms, such as promoting skin-barrier repair, reducing neurovascular hyperreactivity, and controlling inflammatory responses to alleviate corresponding symptoms.
Although studies around the world on sensitive skin and soothing cosmetics have demonstrated remarkable achievements, there are certain challenges that remain: (1) Exploration of novel active ingredients: the continuous search for and validation of new active ingredients with skin-soothing, anti-inflammatory, and skin-barrier-repairing effects, especially ingredients derived from non-traditional sources (e.g., marine organisms and microorganisms); (2) Enhancement of bioavailability: the utilization of nanotechnology to improve the penetrability and stability of active ingredients to enhance their transfer and absorption rates in the skin; (3) Research and development of multi-functional products: the development of compound skincare products with skin-soothing, anti-inflammatory, and moisturizing effects to meet the needs of different skin issues; (4) Investigation of relationships between environmental factors and sensitive skin: the elucidation of the influences of external factors, such as environmental pollution and climate change, on sensitive skin and the exploration of relevant prevention and protection measures; (5) Psychological skin interactions: the determination of the influences of psychological stresses and mood swings on skin sensitivity and the development of corresponding intervention measures.
With the deepening of our understanding of the mechanisms of sensitive skin and progress in research on active substances with skin-soothing effects, we will be able to identify and deal with sensitive skin more effectively and provide a better scientific basis to prevent and treat sensitive skin. This will contribute to further innovations in the cosmetic industry, aid consumers in managing sensitive skin better, and enhance the quality of life of sensitive-skin sufferers.
NOT MY OWN WORK. The above article is taken from:
Chen, B.; Tang, H.; Liu, Z.; Qiao, K.; Chen, X.; Liu, S.; Pan, N.; Chen, T.; Liu, Z. Mechanisms of Sensitive Skin and the Soothing Effects of Active Compounds: A Review. Cosmetics 2024, 11, 190. https://doi.org/10.3390/cosmetics11060190
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