Looking after your skin – and especially sensitive skin – is a serious business, and what we put on our skin can make a huge difference to the way it looks and feels.

But how does a product work when it’s applied to our skin?

Just as our skin can absorb and use vitamins and minerals throughout the body, it can also absorb chemicals with the ability to penetrate down into the deepest layers of the skin.

That’s why it’s so important to be informed about the nature of the ingredients we use on our skin; sometimes, though they might be advertised to do a specific job, and initially appear as if they have added some value, they may in fact do more harm than good.

To understand what happens to our skin when we slather on skin care and other body products, we first need to understand the skin’s components.

As the human body’s largest organ, the skin is composed of three main layers, the epidermis, the dermis and the hypodermis.

• The epidermis is the outer (“Epi” in Greek meaning “upon” or “over”) layer of the skin. It provides a barrier from pathogens and environmental damage and regulates the loss of water. The stratum corneum is the outermost sublayer of the epidermis consisting of dead cells. It is thinnest on the eyelids and thickest on the soles of the feet and palms of the hands. New skin cells are made at the lower levels of the epidermis.
• The dermis is the layer beneath the epidermis that contains the hair follicles, sweat, sebaceous and apocrine glands, the lymphatic and blood vessels and the nerve endings that give us the sense of touch and heat.
• The hypodermis is the bottom layer and lies below the dermis. Its purpose is to attach the skin to the bone and muscle. Up to 50% of body fat is contained in the hypodermis which serves as padding and insulation from temperature variations and physical shock.

The ingredients in our skin care products have a fair way to travel to properly penetrate the skin.

Their ability to penetrate and be absorbed by the skin is dependent on a number of factors:

• The physical and chemical properties of the ingredients, such as the size and weight of the ingredient’s molecules. The smaller the molecules are, the easier they will penetrate between the layers of the skin.
• The concentration of the ingredients on the skin surface.
• The length of time the ingredients have been exposed to the skin.
• The amount of skin that has been exposed to the ingredients.
• The skin’s physical condition, with damaged and heavily exfoliated skin being more likely to allow deeper penetration of ingredients.
• The location of exposure. Thin skin on the eyelids for example is more prone to penetration than thick skin on the soles of the feet.
• The solubility of the ingredients. Oil soluble ingredients penetrate the skin better than water-soluble ingredients because of the waterproof nature of our skin. Additionally some products use ingredients called “penetration enhancers” or “active ingredients” that are surfactants that boost penetration and increase the ability of other ingredients to slip through the skin layers.

Research shows that glycerol-based moisturisers, paraffin (mineral) and vegetable oils increase water penetration when compared to petrolatum.

Even applying a wet towel on the skin increases its water concentration (in the stratum corneum) of almost 60%.

Interestingly in one study vegetable oils reduced swelling of the skin’s stratum corneum.

The ability of ingredients to penetrate the skin does appear to depend on the surfactant used in the skin care formulation, so taking the time to read the ingredients label on your skincare is really pretty critical if you are serious about your skincare, or managing skin conditions like dry skin, rosacea, psoriasis, eczema and dermatitis.

To find out more, keep an eye on our blog, or get in touch via our Facebook or Telegram accounts to ask a question about skincare or skin problems, we’ll be only to happy to help.

Want to know more?

Check out further reading from our references below that were used to help create this article.
Chrit L, Bastien P, Sockalingum GD, Batisse D, Leroy F, Manfait M, Hadjur C.An in vivo randomized study of human skin moisturization by a new confocal Raman fiber-optic microprobe: assessment of a glycerol-based hydration cream. Skin Pharmacol Physiol. 2006;19(4):207-15. PMID:16679823.
Crowther JM, Sieg A, Blenkiron P, Marcott C, Matts PJ, Kaczvinsky JR, Rawlings AV. Measuring the effects of topical moisturizers on changes in stratum corneum thickness, water gradients and hydration in vivo. Br J Dermatol. 2008 Sep;159(3):567-77. PMID:1861678.
Darlenski R, Fluhr JW. In vivo Raman Confocal Spectroscopy in the Investigation of the Skin Barrier.. Curr Probl Dermatol. 2016;49:71-9. PMID:26844899.
Förster M, Bolzinger MA, Ach D, Montagnac G, Briançon S. Ingredients tracking of cosmetic formulations in the skin: a confocal Raman microscopy investigation.Pharm Res. 2011 Apr;28(4):858-72. PMID:21213026.
James W, Berger T,  Elston D (2005) Andrews’ Diseases of the Skin: Clinical Dermatology (10th ed.). Saunders. Page 2-3. ISBN 0-7216-2921-0.
NIOSH (The National Institute for Occupational Safety and Health. 1,4 butanediol. Cas#110-63-4. Centers for Disease Control and Prevention. (http://www.cdc.gov/niosh/ipcsneng/neng1104.html)
Proksch, E.; Brandner, J.; Jensen, J.M. (2008). “The skin: an indispensable barrier”. Experimental Dermatology 17 (12): 1063–1072. PMID 19043850.
Saladin. Human Anatomy. 2007 Ed.2007 ISBN 0071259716.
Stamatas GN, de Sterke J, Hauser M, von Stetten O, van der Pol A. Lipid uptake and skin occlusion following topical application of oils on adult and infant skin. J Dermatol Sci. 2008 May;50(2):135-42. PMID:18164596.
Wilkinson, P.F. Millington, R. (2009). Skin (Digitally printed version ed.). Cambridge: Cambridge University Press. p. 49. ISBN 978-0-521-10681-8.

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