Half of skincare problems trace back to a leaky barrier. Here's what that means and what the evidence says about repairing it.
Your outermost skin is often described as "bricks and mortar": flattened cells (the bricks) held together by a lipid matrix (the mortar). That mortar is made largely of ceramides, cholesterol, and fatty acids. When it's intact, water stays in and irritants stay out. When it's depleted — by over-exfoliating, harsh cleansers, cold weather, or conditions like eczema — skin loses water (measured as transepidermal water loss, TEWL), and gets dry, tight, and reactive.
This is why "barrier repair" moisturizers lean on ceramides. In a randomized trial, adults with moderate eczema used a ceramide-dominant cream and cleanser for 28 days versus a placebo regimen. TEWL and skin hydration significantly improved in the ceramide group while staying flat or worsening on placebo (a statistically significant difference), and people reported less itch and dryness. [1]
Ceramides aren't a magic bullet on their own. The skin's mortar is a mixture — ceramides work alongside cholesterol and fatty acids in roughly physiological ratios, which is why "ceramide + cholesterol + fatty acid" formulas are a common, sensible design rather than ceramide alone.
What this means in practice. If your skin is stinging, flaking, or suddenly reacting to products that used to be fine, the move is usually less, not more: pause actives, switch to a bland gentle cleanser, and use a barrier-supporting moisturizer (ceramides, plus humectants like glycerin or hyaluronic acid to pull in water). Most barriers recover in days to a couple of weeks. Chasing the irritation with more actives is the most common way people make it worse.
This trial was in eczema-prone skin, where the barrier is measurably impaired; the same principles apply to a temporarily over-exfoliated barrier, even if your starting point is healthier.