Skin Sensitivity - How do we correct it

Those with sensitive skin experience more intense and more frequent responses to both the use of personal care products and the environment, a phenomenon known as sensitive skin.  Consumer reports of sensitive skin are often self-diagnosed and can often not be verified by objective signs of irritation.  The incidence of sensitivity being reported is increasing in the population, particularly with the regular use of facial masks to prevent the spread of Covid 19, however is it true sensitivity or environmental sensitivity.

Sensitive skin is characterized by subjective complaints of discomfort without predictable classical visible signs of irritation and without an immunologic response. Although transient redness, itching, stinging dryness or tenderness may accompany adverse sensations, and sensitive skin may be less supple or hydrated, subjects often experience sensory effects only. Sensitivity can be exacerbated by physical factors, chemical factors, psychological stress and hormones. 

Physical Factors such as sunlight, heat, cold and wind, low humidity and the use of facial masks.  When the skin is exposed to the elements and the skin barrier becomes disrupted, an inflammatory cytokine called interleukin 1a is released.  Normally this cytokine is released in response to barrier disruption and triggers the repair of the skin, however when it is continually released then it causes the breakdown of the barrier.  Skin that is exposed to low humidity releases interleukin 1a at a significantly higher level, which is why skin in arid climates struggles to maintain hydration. 

Chemical Factors including cosmetics, can all play a role in the sensitivity of the skin.  Products that have a high pH such as soap can lead to barrier disruption.  Exposure to hard water exposes the skin to abnormally high calcium levels which changes the calcium gradient in the skin, leading to barrier disruption.   

Psychological Stress has been shown to affect the barrier function of the skin and its ability to repair itself.  Psychological stress increases endogenous glucocorticoids by activating the automatic nervous system.  Stress has been shown to delay wound healing and impair the permeability barrier of the skin.  It reduces both the innate and adaptive immunity of the epidermis.    

Hormonal surges and changes occur during the menstrual cycle and also during menopause.  During menopause the oestrogen levels start to decline.  Oestrogen loss is associated with dryness, impaired wound healing and epidermal thinning.  Thinning skin is also a contributing factor leading to increased skin sensitivity. 

Skin sensitivity also changes during the menstrual cycle, with the skin being the most sensitive just before menstruation begins.  Our hormones are linked with our nervous system, and often as we get older skin can become more sensitive due to this. 

Sensitive Skin Type Classifications
Very sensitive skin is reactive to a wide variety of both endogenous and exogenous factors with both acute and chronic symptoms and a strong psychological component. 

Environmentally sensitive is comprised of clear, dry, thin skin with a tendency to blush or flush and reactive to primarily environmental factors 

Cosmetically sensitive skin, transiently reactive to specific and definable cosmetic products. 

Delicate skin, which is characterized by easily disrupted barrier function, not accompanied by a rapid or intense inflammatory response. 

Reactive skin characterised by a strong inflammatory response without a significant increase in permeability. 

Stingers, which are characterised by a heightened neurosensory perception to minor cutaneous stimulation.  Asian skin is renowned for their sensitivity with stinging. 

 One of the largest contributors to sensitivity is barrier impairment.  The permeability barrier of the stratum corneum requires the presence of intracellular lipids that are well packed together.  It is also highly depending on the lipid composition, with certain skin conditions such as rosacea showing altered lipid profiles.  Increased neutral lipids and decreased sphingolipids are associated with barrier impairment and loss of water from the skin. 

The most reliable method of assessing barrier function is to measure transepidermal water loss.  Transepidermal water loss is considered an indicator of the functional state of the stratum corneum, and has proven to be a better indicator of irritant susceptibility than clinical visual scoring.  Clients who have a high baseline measurement of transepidermal water loss have one of the highest levels of reactivity.  Which means if your skin is dehydrated, then you are going to feel cosmetics more and you are more likely to experience stinging and irritation.  Once the barrier is fixed, the irritation disappears in many instances. 

So what causes stinging and pain in the skin? 

The cause of pain and irritation is a receptor present on the surface of cells called Transient Receptor Potential Vanilloid (TRPV1).  It is more commonly known as the pain receptor.  The TRPV1 receptor is responsible for transmitting the sensation of pain upon contact with heat, chemicals and acids.  It is present in our skin, as the skin is first line of defence to the environment. 

Individuals who have hypersensitive and hyper-reactive skin have been shown to have more nerve ending per square centimeter of skin, making them actually feel more.  They have been shown to also have massively elevated levels of TRPV1.   This manifest itself as skin that feels tight, itching and even burning; even though there is nothing harming the skin.  In hypersensitive skin, the free nerve endings are abnormally sensitive and the stimulation of them leads to the release of neuropeptides, including substance P and also histamine. 

The solution for sensitive skin is to reduce the reactivity of the skin by reducing TRPV1.  One such ingredient is Mirabalis Jalapa Extract, which has been proven to improve the comfort of sensitive and reactive skin.  It targets the root causes of sensitive skin by considering the epidermis as both a sensory organ and a physical barrier. 

Mirabilis Jalapa Extract has been shown to stimulate the synthesis of key components of the epidermis including ceramides and hyaluronic acid.  It reinforces the stratum corneum and reduces redness by 54% in 21 days.  Mirabilis reduces TRPV1, which reduces sensitivity at the root of the issue.   

It also reinforces the cell cohesion by 107%, making the skin barrier function stronger.  It prevents irritants from penetrating the skin easily and subsequently increases ceramide and hyaluronic acid production in the skin.  It restores the barrier back to normal.

Other ingredients that been shown to have benefit in reducing sensitivity are Hexapeptide-49.  It has been shown to reduce neurogenic inflammation by reducing the sensation of pain and also itching.  It has been shown to also restore the skin barrier integrity.  It reduces TRPV1 and substance p in the skin. 

The area of the face that is the most sensitive is the nasolabial fold, followed by the malar eminence, chin, forehead and upper lip.  This area in particular is affected by the use of facial masks, with a steep rise in the amount of perioral dermatitis occurring since Covid 19.  During mask wearing the skin is exposed to heat as well as moisture, which is trapped under the mask.  This alters the microbiome, as many organisms over populate in hot and moist environments.  Prebiotics are a good solution for maskne.  Probiotics helps to establish biodiversity, with many prebiotics encouraging the growth of beneficial bacteria only.   

Researchers at Shiseido also discovered that there is a link to biodiversity of the microbiome and hydration levels of the skin, as well as redness.  They analysed and extracted the flora of Japanese women in their 20’s and 30’s.  The diversity of the skin flora was evaluated using the Shannon Diversity index, which evaluates the deviation from both the variety of bacteria and the abundance ratio, and the diversity of bacterial flora on each skin.  The study showed that the abundance of bacteria on the skin correlated to the level of water in the skin.  The number of bacteria was also directly correlated to the level of redness in the skin.  Skin with less diversity was shown to be more sensitive and red.  

 Silicones are also a superior choice for maskne, due to their ability to act as a barrier and prevent friction.  Silicones have been shown to prevent transepidermal water loss, without interfering in the repair of the barrier after acute barrier disruption.  They form a vapour permeable barrier on the skin, preventing pollution particles from adhering and entering pores.  Pollution is another cause of sensitive skins.   

Ingredients that soothe 

The oligosaccharides derived from the brown algae Laminaria digitata, have been shown extensively to decrease skin reactivity and inflammation.  They have also been shown to protect the Langerhans cells and optimise epidermal regeneration. 

Colloidal oatmeal has a long history of soothing the skin and reducing redness.  It also aids moisturisation of the skin. 

Prickly Pear Extract offers extremely high performance with soothing the skin.  Rich in piscidic acid and mucilages.  

Phytosphingosine is a skin-identical ingredient naturally present in the stratum corneum. It is said to improve the appearance of red, inflamed and blemished skin by soothing skin and balancing its microflora.  

Ingredients to avoid for sensitive skins 

Artificial fragrance should be in general avoided for sensitive skins.  Fragrances can contain thousands of compounds with many of them being allergens.  Essential oils known to be an issue for sensitive skins include ylang ylang, lemongrass, narcissus absolute, jasmine absolute and sandalwood oil. 

Strongly anionic surfactants such as Sodium Lauryl Sulfate should be avoided, due to the ability of these surfactants to integrate into the skin barrier, displacing the ceramides and protective natural moisturising factors. 

Sensitive skins can be quickly restored to normal skin sensation with the correct actives and avoidance of ingredients that are known to be barrier disruptive. No single active is a miracle cure, with a combination of actives always being necessary to repair the barrier and soothe the skin.