Eczema: Why It Happens, What Triggers It, and What Actually Controls It

Eczema, also called atopic dermatitis, is one of the most common chronic skin conditions in the world, affecting approximately 230 million people of all ages. Despite its prevalence, it is frequently mismanaged, either undertreated with basic moisturizers that cannot control significant inflammation, or overtreated with prolonged steroids that cause their own problems. As a dermatologist, I see the consequences of both approaches regularly. The key to managing eczema is understanding what it actually is, because that understanding changes the treatment logic entirely.

Eczema is not primarily a dry skin condition that happens to itch. It is a chronic inflammatory disease driven by a defective skin barrier and an immune system that over-responds to environmental triggers. The barrier defect allows irritants, allergens, and microorganisms to penetrate the skin more easily than in people without eczema, triggering immune activation that produces inflammation, itching, and further barrier damage in a self-perpetuating cycle. Treatment that only addresses the surface, without addressing the immune component, will only partially control the condition.

Who Gets Eczema and Why

Atopic dermatitis is strongly genetic. Mutations in the gene encoding filaggrin, a protein critical to the skin barrier, are present in approximately 30 percent of people with atopic dermatitis and are the strongest known genetic risk factor. Filaggrin deficiency causes structural barrier weakness, reduced skin hydration, and increased susceptibility to sensitization to environmental allergens. However, genetics alone does not explain eczema; the condition requires environmental triggers and immune dysregulation acting on a genetically predisposed background.

Eczema is part of the atopic march, a developmental sequence in which eczema in infancy and early childhood often precedes allergic rhinitis and asthma later in childhood and adolescence. This progression reflects a systemic pattern of immune dysregulation rather than separate isolated conditions. Having eczema significantly increases the risk of food allergies, hay fever, and asthma. Children with moderate to severe eczema in early life have a 50 to 70 percent chance of developing asthma or allergic rhinitis by school age.

What Eczema Looks Like

The appearance of eczema varies significantly by age and by how acute or chronic the phase is. In infants, eczema classically presents on the cheeks, forehead, and scalp. In children, the flexures (inner elbows, behind the knees) are the most common location. In adolescents and adults, the hands, face, neck, flexures, and in some cases generalized involvement are typical. Eczema can also affect the eyelids, causing them to appear chronically swollen or thickened.

Acute eczema appears as red, weeping, blistered, or crusted skin that is intensely itchy. Subacute eczema has less intense redness with scaling. Chronic eczema shows thickening and hardening of the skin (lichenification) from repeated scratching, as well as darkening of affected areas. In darker skin tones, eczema may appear more purple than red, follicular eczema (accentuated hair follicles) is more common, and post-inflammatory hypopigmentation or hyperpigmentation after flares can be as distressing as the flares themselves.

Common Triggers

Irritants

Soaps, detergents, shampoos, and cleansers are among the most common eczema triggers. They disrupt the barrier by dissolving the lipid-rich outer layer of skin. Rough fabrics, particularly wool and synthetic materials, cause physical irritation. Sweat is a significant trigger, which is why eczema often flares during exercise, in hot weather, and in people who work physically demanding jobs. Chlorine in swimming pools can be problematic for some patients.

Allergens

In patients with significant allergic sensitization, exposure to house dust mite allergen, pet dander, pollen, and mold can trigger or worsen eczema through systemic immune activation. Food triggers, most commonly egg, milk, peanut, wheat, soy, and fish, are relevant particularly in infants and young children with severe eczema who do not respond adequately to topical treatment. Food allergy testing in adult eczema patients is often overordered; the relationship is more specific to pediatric severe eczema and is not typically the driver of adult eczema.

Skin Infections

Staphylococcus aureus colonizes the skin of the majority of patients with atopic dermatitis and is a major driver of flares. S. aureus produces toxins that act as superantigens, directly activating the immune system and worsening inflammation. When eczema flares appear infected (weeping, crusting, golden crust formation, increased heat and pain), bacterial infection should be suspected and treated. Herpes simplex virus can cause a severe, rapidly spreading form of eczema called eczema herpeticum, which presents as widespread painful blistered lesions and requires urgent antiviral treatment.

Stress

Psychological stress is a well-documented eczema trigger. The mechanism involves the HPA axis and sympathetic nervous system affecting skin immune function and barrier integrity. Many patients can identify periods of significant stress reliably preceding eczema flares. This relationship is bidirectional: eczema itself causes significant psychological distress through sleep disruption, visible appearance, and social impact, creating a cycle that requires attention to both skin and wellbeing.

Treatment

Emollients: The Foundation

Emollient therapy is the cornerstone of all eczema management. Regular, generous application of an unperfumed emollient maintains skin hydration, supports barrier function, and reduces the frequency and severity of flares. This is not optional supplementary care; it is the foundation on which all other treatment rests. The amount required is larger than most patients apply: a typical adult with moderate eczema may use 500 grams of emollient per week. Application immediately after bathing while skin is still slightly damp improves penetration. Ointments are more occlusive and effective than creams but less cosmetically acceptable; lotions are too thin to provide adequate barrier support in most cases. The best emollient is the one the patient will actually use consistently.

Topical Corticosteroids

Topical corticosteroids (TCS) are the most widely used treatment for eczema flares and have strong evidence for efficacy. They are classified by potency from mild (hydrocortisone 1%) to very potent (clobetasol). Appropriate selection depends on the body site and the severity of the flare: mild potency for the face and genitals, moderate to potent for the body and limbs, potent only briefly for thick lichenified skin. The most common clinical problem is undertreatment due to fear of side effects; patients often use very small amounts of mild steroids on significant inflammation for insufficient duration, producing partial response and chronic flares. When used appropriately for the correct duration, topical steroids are effective and safe.

Proactive therapy, applying a TCS twice weekly to previously affected areas even when the skin appears normal, reduces the frequency of flares significantly in patients with moderate to severe atopic dermatitis and is now recommended in guidelines.

Topical Calcineurin Inhibitors

Tacrolimus and pimecrolimus are steroid-sparing topical treatments that inhibit T-cell activation without the atrophy risk of steroids. They are particularly useful on the face, eyelids, and skin folds where long-term steroid use carries higher atrophy risk. They can cause initial burning on application, which tends to resolve after the first few days of use. A historical concern about lymphoma risk has not been borne out in long-term pharmacovigilance data.

Dupilumab and Advanced Biologics

Dupilumab (Dupixent) is an injectable biologic antibody that targets the IL-4 and IL-13 signaling pathway, which drives the type 2 immune inflammation at the core of atopic dermatitis. It has transformed the management of moderate to severe atopic dermatitis that has not responded to topical treatment. Approximately 60 percent of patients achieve a 75 percent or greater improvement in disease severity. It does not cause immunosuppression in the broad sense and has an excellent safety profile. The main side effects are injection site reactions and conjunctivitis in a minority of patients. Newer biologics targeting different aspects of the eczema inflammatory pathway continue to enter the market, expanding options for patients who do not respond to dupilumab.

JAK Inhibitors

Oral JAK inhibitors (upadacitinib, abrocitinib) and topical ruxolitinib are now approved for atopic dermatitis. The oral agents produce rapid, often dramatic improvement in severe eczema and have the advantage of oral administration over injection. They are associated with increased risk of infections and require laboratory monitoring. They are typically used in patients who have not responded adequately to dupilumab or who have specific clinical characteristics making them more appropriate.

When to See a Doctor

If eczema is affecting your sleep, work, or quality of life despite OTC emollients and mild steroids, prescription treatment is warranted. If you suspect infection during a flare, urgent evaluation is appropriate. JourneyDoctors dermatologists can assess severity, prescribe appropriate treatment, and guide management of recurrent flares. Consultations start at $19.

Disclaimer: This article is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional for diagnosis and treatment of any medical condition.

Frequently Asked Questions

Is eczema contagious?

No. Eczema is not infectious and cannot be spread from person to person. It is a genetic and immune condition, not an infectious disease. Misunderstanding of this causes significant social stigma for people with visible eczema, particularly children, and is worth addressing directly when speaking to schools, workplaces, or social contacts of affected individuals.

Can eczema be cured?

There is no cure for atopic dermatitis, but it can be controlled very well in the majority of patients with appropriate treatment. Eczema in children often improves significantly or resolves by adolescence, though a subset have persistent adult eczema. Adults with eczema that begins or persists into adulthood are more likely to have a chronic condition requiring ongoing management.

Does diet affect eczema?

In infants and young children with severe eczema, food allergy, particularly to egg, milk, and peanut, can be a relevant trigger. Allergy testing in this context is worthwhile. In adult eczema, diet rarely plays a significant role, and elimination diets without evidence of specific food allergy are not recommended as they can cause nutritional deficiency and rarely improve eczema in the absence of identified allergy.

Should I avoid bathing if I have eczema?

No. Bathing with lukewarm water (not hot) for 10 to 15 minutes and applying emollient immediately afterward while skin is still slightly damp is actually beneficial. Hot water strips the skin barrier. Soap should be avoided or replaced with a soap-free cleanser. The "soak and seal" approach, bath or shower followed by emollient, is a standard recommendation in eczema management.

Is stress causing my eczema to flare?

Psychological stress can trigger and worsen eczema through effects on skin immune function and barrier integrity. If you notice a clear correlation between stress periods and eczema flares, this is worth acknowledging and addressing as part of your management plan. Mindfulness-based stress reduction and CBT have shown benefit as adjuncts in eczema management in randomized trials.