Eczema disrupts the skin’s protective barrier, allowing moisture to escape and irritants to get in. This creates a cycle of dryness, inflammation, and itching that changes how the skin looks, feels, and functions. Around 204 million people worldwide live with atopic dermatitis, the most common form of eczema, and the effects on the skin range from mild dryness to deep structural changes that persist long after a flare clears.
A Weakened Skin Barrier
Healthy skin works like a brick wall. Tough, flattened cells (the bricks) are held together by a layer of natural oils (the mortar). In eczema, this wall has gaps. Many people with eczema carry mutations in the gene responsible for producing filaggrin, a protein that helps skin cells pack tightly together and retain water. Without enough filaggrin, the structural fibers inside skin cells become disorganized, and the oily layers between cells form incorrectly. The result is a barrier full of tiny cracks.
Those cracks have a measurable consequence: water escapes through the skin far faster than it should. Researchers quantify this as transepidermal water loss, or TEWL. On the forearm, healthy skin loses roughly 4.7 grams of water per square meter per hour. In someone with eczema, that number nearly triples to about 13.3 g/m²/h in dry skin areas. Even skin that looks clinically normal on a person with eczema loses more water than average, sitting around 7.5 g/m²/h on the forearm. This is why eczema-prone skin often feels tight and dry everywhere, not just where rashes appear.
Inflammation From the Inside Out
Eczema isn’t just dry skin. It’s an inflammatory condition driven by an overactive immune response. When the weakened barrier lets allergens, bacteria, and irritants slip through, the immune system overreacts. A specific branch of immunity, dominated by two signaling molecules called IL-4 and IL-13, ramps up and pushes the outer layer of skin into a state of constant inflammation and rapid, disorganized cell turnover. This is what produces the red (or dark brown, depending on skin tone), swollen, warm patches characteristic of a flare.
The inflammation also makes tiny blood vessels in the skin leak fluid, which is why eczema patches sometimes weep or ooze a clear liquid. As that fluid dries, it forms a thin crust on the surface. Beneath the crust, the skin is raw and tender because the rapid immune activity is essentially damaging the tissue it’s trying to protect.
The Itch-Scratch Cycle
Itching is the hallmark symptom, and it does far more damage than most people realize. Inflammation in the skin triggers nerve fibers to grow more densely and become hypersensitive. These sensitized nerves release signaling chemicals that amplify the itch sensation, sometimes to the point where it disrupts sleep and concentration.
Scratching provides brief relief but physically tears the already compromised barrier. That damage triggers a fresh wave of inflammation, which sensitizes the nerves further, which increases the itch. This feedback loop, called the itch-scratch cycle, is one of the main reasons eczema persists. Each round of scratching sustains the inflammatory response through direct barrier disruption, making it progressively harder to break the cycle without intervention.
How Skin Changes Over Time
Acute eczema and chronic eczema look quite different. In an acute flare, the skin is red, swollen, and may blister or weep. The texture is rough and scaly. If flares keep recurring in the same area, the skin gradually undergoes deeper structural changes.
Chronic scratching and inflammation cause the outer skin layer to thicken dramatically, a process called lichenification. Under a microscope, the changes are striking: the ridges that anchor the outer skin to the layers below become elongated and blunted, the collagen fibers in the deeper skin reorganize into vertical bundles (rather than their normal random pattern), and the overall skin becomes noticeably dense and stiff. On the surface, this looks and feels like a patch of leathery, exaggerated skin lines. It most commonly develops on the hands, wrists, ankles, and the creases of elbows and knees, the areas people scratch most.
Skin Color Changes After Flares
Once a flare finally calms down, the skin often doesn’t return to its original color right away. Inflammation disrupts melanin production in the affected area. Some spots heal darker than the surrounding skin (post-inflammatory hyperpigmentation), while others heal lighter (post-inflammatory hypopigmentation). Both types are more noticeable in people with deeper skin tones.
These color changes are not scars, and they do eventually fade, but the timeline is slow. Most pigment changes resolve on their own over several months. In some cases, it can take a year or longer for the skin to match the surrounding tone again. Sun exposure can make dark spots more stubborn, so protecting healing skin from UV light helps speed the process.
Increased Risk of Skin Infections
A compromised barrier doesn’t just let water out. It lets microorganisms in. People with eczema are significantly more prone to bacterial skin infections, particularly from Staphylococcus aureus, which colonizes eczematous skin at much higher rates than healthy skin. Signs of a bacterial infection include increased redness, warmth, swelling, yellow or green crusting, and sometimes pus.
Viral infections are a more serious concern. Eczema herpeticum occurs when the herpes simplex virus (the same virus behind cold sores) spreads across damaged skin. It appears as clusters of small, painful blisters that look punched out, often starting on the face and neck. These blisters weep, bleed, and crust over, and they’re typically accompanied by fever and feeling generally unwell. Eczema herpeticum requires prompt medical treatment because it can spread rapidly across large areas of broken skin.
How External Factors Compound the Damage
Several everyday exposures make eczema’s effects on the skin worse. Alkaline soaps and cleansers raise the skin’s surface pH, which normally sits slightly acidic (around 4.5 to 5.5). That acidity is part of the barrier’s defense system, helping control bacteria and maintain the oily layers between skin cells. Frequent washing with harsh soaps strips those oils and shifts the pH upward, compounding the barrier defects eczema already creates.
Other common triggers include wool and synthetic fabrics rubbing against the skin, rapid temperature changes that cause sweating, low humidity that accelerates moisture loss, and contact with household chemicals like detergents and cleaning sprays. None of these cause eczema on their own, but each one puts additional stress on a barrier that’s already struggling to hold itself together. Identifying and reducing your specific triggers is one of the most effective ways to limit the visible and structural damage eczema does to your skin over time.