Atopic dermatitis, commonly referred to as eczema, is a chronic inflammatory skin condition characterized by dry, intensely itchy skin and a compromised skin barrier function. The intense discomfort leads to scratching, which can make the rash appear to spread or worsen. Eczema itself is not infectious and cannot be transmitted from person to person. The condition is rooted in a combination of genetic predisposition, immune system dysfunction, and environmental triggers.
Eczema is Not Contagious
Eczema is fundamentally an internal disorder involving a hyperactive immune response and a genetic defect in the skin barrier. This means the condition cannot be “caught” from another person through physical contact, sharing towels, or being near someone experiencing a flare-up. Even during a severe flare, the underlying inflammation is not caused by a virus or bacterium that can be passed to others. The confusion often arises because the visible symptoms—red, scaly, and sometimes weeping patches—can resemble infectious skin diseases.
The rash may seem to expand across a person’s body during a flare-up, but this is a sign of the inflammatory disease process becoming more active internally. This expansion is related to the body’s internal state and immune system, not a contagious agent migrating from one spot to another.
The Itch-Scratch Cycle and Skin Damage
The intense itching is the most burdensome symptom of eczema and the primary driver of its apparent “spread.” Scratching provides temporary relief by activating pain receptors that override the itch signals, but this action is destructive to the skin. This creates a self-perpetuating loop called the itch-scratch cycle, which is a major factor in worsening the condition.
Mechanically, scratching damages the already fragile skin barrier. This physical trauma causes increased transepidermal water loss, exacerbating dryness and making the skin more susceptible to irritants and allergens. The damage triggers the release of inflammatory mediators, which intensify the nerve signals responsible for the sensation of itch. This reaction causes the rash to become more red, inflamed, and widespread, giving the illusion that the eczema is actively spreading.
Secondary Risks Caused by Scratching
Beyond increasing inflammation, chronic scratching introduces serious secondary risks. The repeated trauma breaks the skin’s integrity, creating open wounds and fissures. These breaks allow bacteria, most commonly Staphylococcus aureus, to colonize and invade the compromised tissue.
Staphylococcus aureus colonization is more prevalent in individuals with atopic dermatitis, and scratching can turn this into a full-blown skin infection like impetigo or cellulitis. These bacterial infections are transmissible and may present with symptoms such as yellow crusting, excessive weeping, or hot, tender, swollen skin. Furthermore, long-term friction from scratching can cause the skin to permanently thicken and become leathery, a condition known as lichenification. This structural change can also lead to post-inflammatory hyperpigmentation or hypopigmentation.
Strategies for Managing the Urge to Scratch
Breaking the itch-scratch cycle is one of the most important steps in managing eczema flares and preventing complications. One immediate, practical step is to ensure fingernails are kept short and smooth to minimize skin damage from unconscious scratching, especially during sleep. Applying a cold compress or a refrigerated emollient to an intensely itchy spot can help numb the nerve endings and override the urge to scratch.
Frequent and liberal application of thick moisturizers, such as ointments or creams, helps to restore the compromised skin barrier and reduce dryness. When the urge to scratch is overwhelming, try applying firm pressure or gently pinching the itchy area instead of raking the skin. Using protective garments, like cotton gloves or mittens at night, can also prevent inadvertent scratching.