Everyone has heard of the skin barrier by now, but what exactly is it?
As with many skincare terms, “skin barrier” pops up a lot in social media posts by influencers and in skincare ads, so much so that it starts losing its meaning. This isn’t anybody’s fault, and most likely the term first entered the cultural zeitgeist when it was used by experts who either explained it at the time, or assumed everyone knew what they were talking about. Many subsequent uses didn’t explain it very much at all, because it sounds so basic: it is a barrier that protects the skin. We at Not Just Skincare know that details are important and think you should know the facts. So let’s break it down.
The skin is made up of three distinct layers, namely the hypodermis, the dermis and the epidermis (from the inside out). The hypodermis contains fat deposits, nerves, blood vessels and other structures like hair follicles. The dermis consists of multiple layers, starting with the reticular layer, which is made up of dense fibrous connective tissues like collagen fibres. On top of the reticular layer is the papillary layer, which is more loosely composed of connective tissues that bind the epidermis.
The epidermis is the outermost layer and is arguably the most complex and active layer of the skin. The deepest layer of the epidermis (the stratum basale) houses the cells that produce melanin, nerves, immune cells, and keratin producing cells. The second layer of the epidermis, the stratum spinosum, contains irregular, spiny cells that reach out and connect to each other, as well as specialised immune cells. The next layer, the stratum granulosum, contains diamond shaped cells with specialised inner components that produce keratin precursors and the fatty substances that will coat the skin cells to help them stick to each other. The stratum lucidum is present in the thicker skin of the hands and feet, which also contains keratin derived products. The outermost layer, the stratum corneum is composed of dead keratin-producing cells and keratin that form scale-like structures.
The skin is often described as being the body’s first line of defence against infections and injuries. It is full of immune cells that quickly signal the immune system to neutralise microorganisms so that they can’t wreak havoc inside our bodies. This is why the skin itself is referred to as a barrier. However, when most people refer to the ‘skin barrier’ they are talking about the epidermis, and specifically the stratum corneum and its ability to select what is allowed to pass through from the inside and the outside. The epidermal barrier has several functions, including permeability-, antimicrobial-, antioxidant-, immune response- and photoprotection barriers.
The most important part of this function is to maintain healthy water levels within the epidermis, because water is necessary for the epidermis and its enzymes to work properly in order to maintain elasticity and optimal skin shedding. Optimal epidermal functioning can be disrupted by harsh skin treatments like physical exfoliants, skincare products with bad formulations, irritants, allergens, certain medications and routines where active ingredients interact negatively with each other. Increased and continual water loss out of the stratum corneum can cause serious problems like redness, dry skin, cracking, advanced chronic dryness, eczema and dermatitis. If any of these occur, one should contact a dermatologist.
At Not Just Skincare, we believe in prevention. While the extreme products that promise quick results for acne, ageing, etc. seem promising in our fast paced, results-driven society, they often do more harm than good. Our ranges of gentle formulations cleanse mildly, soothes the skin, and hydrate deeply, all to protect the skin barrier.
(Del Rosso & Kircik, 2025; Yousef, 2024)
Sources:
Del Rosso, J. Q., & Kircik, L. (2025). Skin 101: Understanding the Fundamentals of Skin Barrier Physiology-Why is This Important for Clinicians? J Clin Aesthet Dermatol, 18(2), 7-15. https://pmc.ncbi.nlm.nih.gov/articles/PMC11896616/
Yousef, H. A., M; Fakoya, A. O.;Sharma, S. (2024). Anatomy, Skin (Integument), Epidermis. StatPearls [Internet]. https://www.ncbi.nlm.nih.gov/books/NBK470464/
