Do you think you have sensitive skin? Or have you been diagnosed with sensitive skin? Sensitive skin is a very complex subject with about 70% of the population believing to have sensitive skin. Medical science classes sensitive skin as a condition rather than a disease and some research studies go as far as distinguishing between skin reactions as subjective and objective. Subjective reactions are the ones said to be influenced by personal feelings, tastes, opinions etc whereas objective are the ones caused by actual biological incompatibility, physical reactions.
You might be surprised that “subjective skin reactions” are even a thing but there are a lot of factors that can fuel such subconscious reaction including the fear of chemicals, aka chemophobia, which I will write about soon, or other factors like stress (although this might partially count as objective, it is very difficult to separate).
In subjective cases no medical signs of irritation are detected but the sufferers can experience feelings such as itching, burning, stinging, a tight sensation and more, and usually complain of such effects when using substances that “are not known to be irritants”. This was a statement in one of the published research papers I read and I found it very interesting for two reasons: have the researchers taken into consideration that: (a) perhaps those substances are irritant for some and not others (b) perhaps there are levels of sensitivity, some being more sensitive than the sensitive (hyper sensitive?).
There is an interesting study by T. Yokota et al. that classifies sensitive skin in three types in an attempt to provide the right type of treatment for the right sensitivity type.  I would personally love to see more research into these. But while the idea of a psychosomatic response (psychological influence into a physical response) might sound strange, it is actually fairly common for psychological responses to manifest in physical symptoms for whatever reason (you don’t have to suffer from a mental disease for this to happen).
If we ignore the psychosomatic factors, skin sensitivity can arise due to a couple of reasons such as:
(a) Damaged skin barrier.  Our skin is the body’s first defence, a shield, if you like, from the outside world. Some studies have suggested that sensitive skin has a weaker barrier when compared to normal skin which is usually due to a thinner outer layer (stratum corneum). This not only irritates and disrupts normal skin function, it also allows irritant (or other) substances to penetrate deeper into the skin causing a reaction that might not have happened if the barrier was healthy.
A damaged skin barrier could be due to many factors with the most common being loss or reduction of a key compound which keeps our skin healthy, some studies suggest it could be due to lowering of keratinocytes  and ageing which in effect is the same as the above as it reduces the good molecules present in our skin. Don’t despair though as some studies have effectively shown that cosmetics, such as creams and cleansers, can truly help contain and even repair some of the damage .
(b) Neurological factors. Sensitive skin sufferers have been found to have more nerve receptors than the normal type suggesting that allergic or sensitivity responses are almost inevitable.  This could be due to a vast number of nerves present, picking up all sorts of signals and noise, but also due to damaged sensors or a higher chance of having damaged sensors.
(c) Inflammatory response. As with a lot of things in our body, some conditions can have a domino effect. If the sensitive skin sufferer has damaged skin, or thinner than normal for whatever reason (could this also be inherited I wonder), then they are more likely to have an inflammatory response as the body’s first defence barrier is compromised. The inflammation will in turn further damage the skin barrier and nerve endings  leading to sensitivity, inflammation and possible allergies. You can clearly see here that this is a viscous circle so we should really take the protection of our skin barrier seriously.
(d) Physiological factors such as hormones and gender. Ladies we won the biological lottery once again. Many studies on different skin matters show that the female skin is slightly thinner than the male one and that sensitivity, and more generally the chance for a skin reaction, is higher during menstruation. If you suffer from sensitive skin you might want to consider going a bit more natural during those days of the month. Not ideal, I know.
(e) Other exogenous factors such as: environmental conditions including pollution and weather, air conditioning, cleaning products and cosmetics, clothing, food and more.
So perhaps the best way of defence is to protect the…you guessed it…layer of defence, our skin barrier, from any or further damage. It is very difficult to fully map a complicated process such as the skin barrier function, and relate it to specific molecules, because there are so many that take part. There are a few though which are commonly accepted, well researched and shown to be strongly related.
- Hyaluronic acid. This miracle worker molecule has been labelled “the fountain of youth” justly, for its incredibly moisturising abilities (holds 1000 times its weight in water) and cell growth factors. This molecule is found naturally in our skin and so lack of it has been linked to reduction of skin volume, which can compromise the skin’s defence and also lead to wrinkles, reduction of collagen synthesis which also has healthy function and cosmetic effects, and even lack of growth and division of cells. If you want my opinion, this is a must have molecule in your skin care routine. For more in-depth information have a look at my “Hyaluronic acid – The fountain of youth?” post.
- Free radicals. Free radicals cause skin damage and are found not only due to environmental pollution but are also produced naturally in our bodies during cell processes. Free radicals can attack, disrupt and even destroy all sorts of molecules and processes such as cell membranes, proteins and even DNA leading to cell ageing and death. As a result, minimising the activity or availability of such species is very important for healthy skin function. To counter these highly reactive species look for anti-oxidant molecules such as vitamins C and E. For more info on how they work in relation to skin, what they do and how much your cosmetic product should contain see my “Vitamins C & E – Do they work in skin care?” and“Vitamin A in skin care – Is it worth it?” posts.
- The fatty acid ceramide (N-fatty acyl sphingosine) is also an important component of the skin barrier. This fatty acid plays a role in many processes, similar to hyaluronic acid, such as maintenance of the structural stability, moisture retention and damage repair of the skin. 
- Balance of other nutrients, lipids and proteins in our skin. This is a no brainer. The moment the balance of our skin chemistry is interrupted then you can almost be sure that it will have some effect which could manifest in many ways such as dryness, sensitivity, irritation, wrinkles, a skin disease, you name it. There are many simple things you can do to keep this huge and complex organ healthy such as eating healthy, getting enough sleep, drinking enough water, cleaning and moisturising your skin daily etc.
If you are curious if your cosmetics contain any anti-allergic and anti-irritant ingredients here’s a list of some of the most commonly used ones: hydroxytyrosol, procyanidin, echium oil, echinacoside, brown algal polysaccharides, piscidic acid, total glucosides of peony, tea polyphenol, trans-4-tertiary butyl cyclohexanol, peony phenolic glycosides, baicalin, nightshade alkali, stachyose, acyl anthranillic acid, quercetin, β-boswellic acid, farfara ketone and more. 
It is important to note, that although skin sensitivity, irritation and allergies might have similar symptoms or even appear the same to some, they are three different mechanisms of action and reaction. If you seriously suffer from sensitive skin reactions, whatever those might be, it might be a good idea to keep a diary with as much detail as possible to help you and your dermatologist pinpoint the triggers. The most common sensitive areas reported are, in first place: the smile lines, second place: the cheeks and last but not least: the reproductive organ skin. No shocking revelations here.
There are various tests which can truly evaluate your skin’s sensitivity such as: a stinging test,  exposure to lactic acid, [9, 10] exposure to capsaicin,  exposure to nicotinate and sodium lauryl sulphate,  evaluation of the itching response, washing and exaggerated immersion tests,  behind the knee exposure tests  and more. Referral to such tests will vary in different countries and cases so consult your medical doctor, do no try them at home!
As sensitive skin is not a disease but rather a condition, there is no real treatment for it. Suggested “treatments” are processes that tend to limit, control or even eliminate the symptoms and triggers. When it comes to sensitive skin, it is all about damage control and prevention. Depending on how serious the inflammation is, anti-flammatory drugs can help minimise the response but they will not eliminate the problem. Treat your skin properly and with care, it is the largest organ in your body after all.
- http://doi.org/10.1111/j .1468-2494.2012.00754.x
- Yokota T., Matsumoto M., Sakamaki T. et al., Classification of sensitive skin and development of a treatment system appropriate for each group, IFSCC Mag., 2003, 6, 303-307.
- Qingchun L., Sensitive skin research progress, Skin Dis. Sex. Transm. Dis., 2013, 35, 264-265.
- http://doi.org/10.1111/ics.1 2283
- Grove G. L., Age-associated changes in intertegumental reactivity, In: Aging skin, Properties and Functional Changes, Léveque J. L. and Agache P. G. eds, New York, Basel, Hong Kong, 1993, 227-237.