Eczema, Atopic Dermatitis & Allergies

Written by Empire Medical Training Editorial Team

Medically reviewed by Sherry Wehner, MD Board-Certified Pathologist & Dermatopathologist; Aesthetic & Wellness Medicine

Updated June 2026 ·10 min read

Eczema — clinically, atopic dermatitis — is one of the conditions Dr. Sherry Wehner names first when she lists the everyday complaints that bring patients into an allergy practice, alongside conjunctivitis, sinusitis, rhinitis, and asthma. It is also one of the most misunderstood. Patients arrive certain that a single food is the culprit and that an allergy panel will reveal it. The honest clinical answer is that eczema is not simply “caused by an allergy,” and that broad allergy testing is one of the most overused tools in its workup. This guide, drawing on Dr. Wehner’s dermatology and dermatopathology background, explains what atopic dermatitis actually is, how it relates to allergic disease, and where testing helps and where it misleads.

This page sits within Empire’s Allergy Testing & Treatment resource center. It is clinical education for providers, not medical advice or a substitute for individualized care, and nothing here should be read as a treatment protocol.

What atopic dermatitis is

Atopic dermatitis is the medical name for the most common form of eczema: a chronic, relapsing, intensely itchy inflammatory skin condition. The cardinal symptom is itch — patients scratch, the scratching damages the skin further, and a self-perpetuating itch-scratch cycle sets in. On exam it presents as dry, red, scaly, sometimes weeping or thickened patches, classically in the flexural creases in older children and adults and on the face and extensor surfaces in infants.

It is worth being precise about terms, because eczema is a family rather than a single entity. Atopic dermatitis is the allergic-spectrum form discussed here. Contact dermatitis — the T-cell-mediated reaction to nickel, fragrances, preservatives, and similar agents — is a different mechanism that is evaluated with patch testing, not the IgE-based skin-prick test. Distinguishing the two matters, because the workup and the role of allergy testing differ entirely.

The skin-barrier and immune model

Modern understanding of atopic dermatitis rests on two intertwined defects: a skin barrier that does not hold up, and an immune system that overreacts. Think of healthy skin as a brick wall — tightly packed cells held together by lipids that keep water in and irritants out. In atopic dermatitis that wall is leaky. The most cited contributor is loss-of-function in filaggrin, a structural protein essential to forming a competent outer skin layer; when filaggrin is deficient, the barrier loses water, dries out, cracks, and lets allergens and microbes through.

That breached barrier sets off the second defect. Allergens and irritants that penetrate inflamed skin are met by an exaggerated type-2 immune response, which keeps the skin inflamed and itchy and drives further scratching and barrier damage. The clinical takeaway is that the barrier defect and the immune overactivity feed each other. It also reframes what we call “allergy” in eczema: much of the IgE sensitization seen in atopic patients is plausibly a consequence of allergens entering through broken skin, not the original cause of the rash. This is why barrier repair sits at the center of management rather than at the edges.

Eczema and the atopic march

Eczema rarely travels alone. It is typically the first stop on the atopic march — the well-described tendency for allergic conditions to appear in sequence across childhood: eczema in infancy, then food allergy, then allergic rhinitis, and ultimately asthma in a meaningful subset. Wehner’s epidemiology frames the stakes: allergic disease affects more than 56 million Americans and is the sixth leading cause of chronic disease in the U.S., with strong genetic loading — one allergic parent raises a child’s risk by 30 to 50 percent, and two parents by 60 to 80 percent.

The barrier model offers a plausible thread connecting these stages: when allergens are presented to the immune system through inflamed, broken skin rather than through a healthy gut or airway, the body is more likely to mount an allergic, IgE-driven response. That hypothesis has reframed eczema from “just a rash” into a potential gateway for later allergic disease — which is exactly why identifying and treating it early, with the barrier in mind, matters beyond the skin itself.

The relationship between eczema and allergies

Here is the nuance that trips up patients and clinicians alike. People with atopic dermatitis are far more likely than the general population to be IgE-sensitized to foods and environmental allergens — and allergic triggers can genuinely flare the skin. But sensitization is not the same as a clinically relevant allergy, and eczema is not simply “caused by” an allergy. A patient can have a strongly positive test to a food they eat every day with no skin reaction whatsoever.

The mechanism running underneath all of this is the same allergic cascade Wehner reviews in the course: when an antigen binds IgE on a mast cell, the cell degranulates and releases histamine and other mediators, producing itch, redness, and swelling. In eczema, that cascade can contribute to flares, but it operates on top of an already-broken barrier and a primed immune system. So the right framing for patients is layered: the barrier and immune dysregulation are the foundation; specific allergic triggers are aggravators that vary from person to person.

The role — and limits — of allergy testing in eczema

Allergy testing in eczema has a legitimate but narrow place, and it is genuinely overused. The core problem is the high rate of clinically irrelevant positives. Atopic patients are sensitized to many things; a broad food panel will light up, and acting on every positive can push a patient into needless, sometimes harmful, dietary restriction without improving the rash.

Wehner’s practical framing is that testing should follow a clinical history, not replace it. Targeted testing makes sense when the history points to a specific immediate reaction — hives, swelling, or worse, within minutes of a particular food. Fishing with large panels in a patient whose only complaint is chronic eczema does not.

The eczema patient also illustrates the limits of the testing methods themselves:

• Skin-prick testing is the everyday first-line tool, but severe eczematous dermatitis on the test site is a recognized contraindication — inflamed skin makes the wheal-and-flare impossible to read reliably.
• Dermatographism, common in atopic patients, produces a wheal from mere friction, generating false positives that can render a whole prick panel uninterpretable.
• When skin testing is unsuitable, blood (specific-IgE) testing is the practical alternative — it can screen many antigens and is useful precisely in patients with extensive eczema, dermatographism, or ichthyosis — though it carries its own false positives and still requires clinical correlation.

A particular caution: IgG food “sensitivity” panels are not validated to diagnose food allergy and are not recommended by major allergy bodies. For suspected non-allergic food intolerances, a careful elimination-and-reintroduction approach is the practical tool — covered in our companion guides on food allergies versus food sensitivities and on elimination diets. The specific contraindication lists, how to document them, and when to choose blood over skin testing are taught in depth in Empire’s course.

Management at a high level

Because eczema is a barrier-and-inflammation disease, management targets exactly those two fronts — not the allergy panel. The components, kept deliberately high-level here, are:

• Barrier repair and moisturization. Frequent emollient use, gentle non-stripping skin care, and lukewarm bathing are the foundation. Restoring the barrier reduces water loss, allergen entry, and flares.
• Topical anti-inflammatories. Topical corticosteroids and steroid-sparing options control the immune-driven inflammation during flares. Specific agents, potencies, and regimens belong to current guidelines and individualized judgment.
• Trigger identification and avoidance. Where a genuine, history-supported allergic or irritant trigger exists, avoidance helps — but it supplements barrier and anti-inflammatory care rather than replacing it.

Crucially, allergy testing does not cure eczema, and providers should never imply otherwise to a patient. For clinicians interested in the root-cause and immune context behind atopic disease — barrier integrity, the type-2 immune axis, and the gut-skin relationship — our functional medicine resource center provides additional framing.

When to refer

Eczema sits on a spectrum, and not every patient belongs in a general allergy-testing practice. Mild, barrier-responsive disease is well within scope. Severe or uncontrolled atopic dermatitis — widespread, debilitating, infected, or unresponsive to first-line care — warrants referral for specialist management, which may include systemic or biologic therapy beyond the scope of an in-office allergy program.

Two of Wehner’s broader safety rules apply directly here. A patient with a history of anaphylaxis or systemic allergic reactions is a more complex case to refer to a board-certified allergist/immunologist rather than test routinely — and any skin testing must be performed with emergency preparedness on hand, because anaphylaxis is a medical emergency whose first-line treatment is intramuscular epinephrine. The honest posture throughout is that allergy testing and treatment require proper training, the right setting, and emergency readiness — which is exactly what structured education delivers.