Sensitive Skin has a Weakened Barrier
The stratum corneum, the outermost layer of the epidermis (the epidermis is the outermost layer of the skin), is made up of skin cells and oils that sit together like bricks and mortar. There are, on average, 20 layers of cells in this outermost, outermost layer of skin (depending on the part of the body). This brick wall acts as a permeable layer that defines the boundary of our body, keeping microscopic foreign substances out while also allowing the transfer of moisture and heat between the body and the outside world. This is often referred to as skin’s “barrier function.” Those with sensitive skin have a more permeable epidermis, making the skin more vulnerable to pathogens and allergens and making it harder for the skin to attract and retain moisture. Some people naturally produce less oil and are predisposed to more permeability, but anyone’s skin can become sensitive when it is dry from environmental factors like exposure to dry air or hot water.
Skin Barrier and the Itch-Scratch Cycle
When the barrier isn’t performing optimally: when the oils are depleted, or the cells aren’t lying flat and tightly together, the skin isn’t able to regulate moisture properly and it gets very dry. Dry skin is a leading cause of itch for anyone,1 but those with sensitive skin conditions like eczema or atopic dermatitis may also have increased proteins and nerve endings that make them physically more sensitive to sensations and itch.2 We feel a compulsive desire to relieve itching through the automatic and natural response of scratching the skin. While this provides temporary relief, the act of scratching irritates the skin and further disrupts the skin’s barrier function. As the barrier suffers, the skin becomes more susceptible to pathogens and irritants that trigger the immune response. The result is skin that is even more itchy, irritated and ultimately inflamed. This is the genesis of the itch-scratch cycle.
Break the Cycle – Defend the Barrier
Moisturizers formulated specifically for sensitive skin can be very effective in reducing the severity of the itch-scratch cycle by supporting and reinforcing the skin’s natural barrier function. Moisturizers serve 3 purposes: attracting moisture to the stratum corneum, reducing trans-epidermal water loss (evaporation of the water from your skin) and replenishing with oils that mimic the lipids in our natural barrier. Moisturizers come in many forms and are classified by the amount of oil and water they contain. Products high in oil will often be more effective in sealing in moisture, while creams tend to have added benefits like re-hydrating skin with humectant ingredients. Creams are often less greasy and preferred for their “skin feel” but an oil-based balm or ointment is least likely to sting extremely dry, cracked skin and is superior in reducing trans epidermal water loss.
What to know about Moisturizers
The best moisturizers are mild to the skin, pH neutral (the emulsion of water and fat on the surface of the skin is slightly acidic with a pH of 5-5.5 and the best moisturizers to curb itch will be close to this value), and contain no fragrances, dyes or harsh preservatives. Moisturizers formulated specifically for sensitive skin may also contain key functional ingredients proven to help alleviate itch. Colloidal Oatmeal (oatmeal in colloid form: ground up and suspended in water or other liquids, it forms a creamy film) is a well-established ingredient that, in certain concentrations, even carries OTC (over the counter) drug status as an effective ingredient to temporarily relieve the itch associated with rashes or eczema.
Soak and Seal
Moisturizers are most effective when the skin is a little damp, when the cells are plump with water. It can be time consuming, but the absolute best way to minimize the impact of itchy, dry, sensitive skin is to properly moisturize every time your skin gets wet. After bathing, gently pat dry, leaving skin a little damp and cover completely in a cream, oil-based balm or a body oil. Carry a moisturizing cream with you so you can reapply each time you wash your hand and throughout the day when your skin feels dry.
1) Journal of Clinical & Aesthetic Dermatology, July 2009, pages 1-35
2) Seminars in Cutaneous Medicine and Surgery, June 2011, pages 1-30