Eczema Is Not One Thing: The 7 Types of Dermatitis and Their Microbiome Connection

Most people use the word "eczema" to mean one thing. A condition with itchy, inflamed skin that flares unpredictably and is frustratingly difficult to manage. But eczema isn't one condition — it's a family of distinct skin disorders, each with different causes, different triggers, and different underlying mechanisms.

This distinction matters more than most people realize. Because treating atopic dermatitis the same way you treat seborrheic dermatitis — or reaching for a one-size-fits-all eczema cream when you actually have perioral dermatitis — can mean years of mismatched care. At Treats Lab, our Ato Biome Care philosophy is built around understanding what's actually happening in the skin rather than just treating the surface symptom. And that starts with knowing which type of dermatitis you're dealing with — and whether the skin microbiome is part of the picture.

TL;DR

• According to the National Eczema Association, there are seven distinct types of eczema — and it's possible to have more than one at the same time
• Eczema is an umbrella term covering multiple distinct skin conditions — each with different causes and different microbiome profiles
• Atopic dermatitis is the most common type and is directly driven by microbiome dysbiosis — specifically Staphylococcus aureus overgrowth and reduced microbial diversity
• Seborrheic dermatitis is driven by Malassezia yeast overgrowth — a completely different microbiome imbalance that requires a different approach
• Perioral dermatitis has a microbiome component and is frequently triggered or worsened by topical steroid use on the face
• Contact dermatitis, dyshidrotic eczema, nummular eczema, neurodermatitis, and stasis dermatitis have different primary causes — some with limited microbiome involvement
• A microbiome-supportive approach is most directly relevant to atopic dermatitis, seborrheic dermatitis, and perioral dermatitis
• The Bi-Om Complex in Treats Lab formulas addresses both S. aureus and Malassezia — making it relevant to multiple dermatitis types
• The R+R Barrier Recovery Mist can support skin comfort and barrier recovery after contact dermatitis irritant exposure
• Always work with a dermatologist to confirm which type of dermatitis you have before building a skincare routine around it

In This Article

1. What Is Eczema and How Does It Relate to Dermatitis?
2. What Are the Seven Types of Eczema and Dermatitis?
3. Which Types of Dermatitis Have a Microbiome Connection?
4. Which Types of Dermatitis Are Outside the Microbiome Picture?
5. How Does the Skin Microbiome Drive Eczema Flares?
6. What Does a Microbiome-Supportive Approach Look Like for Eczema-Prone Skin?
7. FAQs About Types of Eczema and Dermatitis

What Is Eczema and How Does It Relate to Dermatitis?

The terms eczema and dermatitis are often used interchangeably — and the confusion is understandable. Dermatitis literally means inflammation of the skin. Eczema refers to a group of conditions that cause the skin to become inflamed, itchy, and irritated. In practice, most forms of eczema are types of dermatitis, and most types of dermatitis present with eczema-like symptoms.

The most important thing to understand is that neither eczema nor dermatitis is a single diagnosis. They're categories — broad descriptors that cover multiple distinct conditions, each with its own cause, mechanism, and appropriate treatment approach.

According to the National Eczema Association, there are seven distinct types of eczema — and it's possible to have more than one at the same time. Over 31 million Americans have some form of eczema, making it one of the most prevalent skin conditions in the country. But within that number, the experiences are remarkably varied — because atopic dermatitis, seborrheic dermatitis, contact dermatitis, and perioral dermatitis are not the same condition. They share surface symptoms but diverge significantly in what's driving them underneath.

Understanding which type you have is the first step toward understanding what your skin actually needs.

What Are the Seven Types of Eczema and Dermatitis?

Here's a clear overview of all seven types recognized by the National Eczema Association:

Atopic Dermatitis
The most common form of eczema, affecting up to 20% of children and 10% of adults. Characterized by dry, itchy, inflamed skin that typically appears in the creases of elbows, knees, and on the face. Strongly associated with immune hypersensitivity, barrier dysfunction, and skin microbiome dysbiosis. Often appears alongside asthma and hay fever.

Seborrheic Dermatitis
A chronic inflammatory condition affecting oil-rich areas of the skin — the scalp, face (particularly around the nose, eyebrows, and ears), and sometimes the chest. Characterized by redness, flaking, and scaling. Driven primarily by an overgrowth of Malassezia yeast. Dandruff is a mild form of seborrheic dermatitis.

Contact Dermatitis
Caused by direct skin contact with an allergen or irritant — fragrances, metals (particularly nickel), certain preservatives, cleaning products. Comes in two forms: allergic contact dermatitis (immune-mediated reaction to a specific allergen) and irritant contact dermatitis (physical damage from repeated exposure to an irritant). The primary intervention is identifying and removing the trigger.

Dyshidrotic Eczema
Small, intensely itchy blisters that appear on the palms, fingers, and soles of the feet. Often triggered by stress, sweating, seasonal allergies, or metal sensitivity. More common in warm months. Not directly driven by microbiome dysbiosis.

Nummular Eczema
Coin-shaped patches of irritated skin, most commonly appearing on the arms and legs. Often associated with very dry skin and can be triggered by insect bites, skin injuries, or environmental dryness. Cause is not fully understood; limited microbiome research specific to this type.

Neurodermatitis (Lichen Simplex Chronicus)
Characterized by intense, localized itching that leads to repeated scratching, creating thick, scaly, leathery patches of skin. The itch-scratch cycle is the defining feature — scratching provides temporary relief but worsens the skin condition over time. Triggered primarily by stress, anxiety, and nervous system hypersensitivity. Not primarily microbiome-driven.

Stasis Dermatitis
Occurs in the lower legs as a result of poor circulation and fluid buildup — typically in older adults or those with chronic venous insufficiency. The primary cause is vascular rather than immunological or microbial. Outside the scope of microbiome-supportive skincare.

Perioral Dermatitis
A specific inflammatory rash that appears around the mouth, nose, and sometimes eyes. More common in women. Frequently triggered or worsened by topical steroid use on the face. Has a microbiome component involving disruption of the facial skin flora. While not one of the NEA's official seven, perioral dermatitis is closely related and commonly discussed alongside the eczema family of conditions.

Which Types of Dermatitis Have a Microbiome Connection?

This is the question that matters most for understanding what kind of skincare approach can actually help.

The skin microbiome — the community of bacteria, fungi, and microorganisms living on the skin's surface — plays a direct and well-documented role in some types of dermatitis. In others, the primary driver is elsewhere. Being honest about this distinction is important: a microbiome-supportive approach isn't the answer for every type of dermatitis. But for several of the most common types, it's one of the most important interventions available.

Atopic Dermatitis — strong microbiome connection
Atopic dermatitis is now understood as a chronic inflammatory disease driven by a self-reinforcing cycle involving skin barrier dysfunction, immune dysregulation, and microbiome dysbiosis.¹ The hallmark of this dysbiosis is the overgrowth of Staphylococcus aureus — a bacteria that at normal levels is a harmless skin resident, but in atopic skin proliferates and directly triggers the immune overreaction that drives flares. Approximately 90% of people with atopic dermatitis show S. aureus colonization in lesional skin, compared to around 5% of healthy skin.¹ Supporting microbial balance — reducing S. aureus dominance and restoring diversity — is one of the most direct ways to address the atopic cycle.

Seborrheic Dermatitis — strong microbiome connection
Seborrheic dermatitis is driven by a different microbiome imbalance — an overgrowth of Malassezia yeast, which is part of the normal skin flora but becomes problematic when it proliferates beyond its typical range. Malassezia feeds on the fatty acids in sebum, and its metabolic byproducts trigger an inflammatory response that produces the redness, flaking, and scaling characteristic of seborrheic dermatitis.² Antifungal approaches are the conventional treatment; microbiome-supportive botanicals with documented antifungal activity against Malassezia are an important complementary approach.

Learn more about: Atopic Dermatitis vs Seborrheic Dermatitis

Perioral Dermatitis — moderate microbiome connection
The exact cause of perioral dermatitis isn't fully established, but disruption of the facial skin microbiome is increasingly recognized as a factor. Topical steroid use on the face — one of the most common triggers — alters the microbial environment in ways that can precipitate or worsen the condition. Supporting the skin's microbial balance while avoiding further disruption is an important part of managing perioral dermatitis.

Learn more about: Perioral Dermatitis

Which Types of Dermatitis Are Outside the Microbiome Picture?

Honesty matters here. Not every type of dermatitis is primarily driven by microbiome dysbiosis — and claiming otherwise would be inaccurate and unhelpful.

Contact Dermatitis is primarily driven by allergen or irritant exposure. The most important intervention is identifying and removing the trigger. While a microbiome-supportive approach isn't the primary treatment for contact dermatitis, barrier support plays an important role in recovery — particularly after irritant exposure, when skin is compromised and reactive. The R+R Barrier Recovery Mist can help support skin comfort during this recovery period, providing lightweight hydration and calming relief from redness and itch without adding further irritation.

Dyshidrotic Eczema is associated with sweating, stress, and seasonal allergies — triggers that don't primarily involve the skin microbiome. Barrier support and trigger management are the most relevant approaches.

Nummular Eczema has unclear causes and limited microbiome-specific research. General barrier repair and moisturization are appropriate supportive measures.

Neurodermatitis is neurological in origin — driven by the itch-scratch cycle triggered by stress and anxiety. Breaking the cycle through stress management and avoiding scratching is the primary intervention. Barrier support can help with skin comfort but doesn't address the root cause.

Stasis Dermatitis is vascular in origin and requires circulatory intervention — compression therapy, elevation, and treatment of underlying venous insufficiency. Skincare plays a secondary supportive role at best.

This transparency matters because it shapes how you approach your routine. If you have contact dermatitis, the most important thing you can do is identify your triggers. If you have atopic or seborrheic dermatitis, the microbiome is a central piece of the puzzle.

How Does the Skin Microbiome Drive Eczema Flares?

For the types of dermatitis where the microbiome is directly involved — atopic dermatitis, seborrheic dermatitis, and perioral dermatitis — understanding the mechanism helps explain why conventional approaches often fall short.

In healthy skin, the microbiome is diverse. Different species of bacteria and fungi coexist in a balanced ecosystem, keeping each other in check and collectively helping to regulate the skin's immune response, maintain barrier integrity, and protect against pathogens.

In atopic dermatitis, that diversity collapses. S. aureus dominates, producing toxins that directly trigger immune overreaction, damage barrier proteins, and create the conditions for chronic inflammation. The barrier becomes more permeable — which allows more S. aureus to colonize — which drives more inflammation — which further weakens the barrier. A self-reinforcing loop that's difficult to break with barrier repair alone.¹

In seborrheic dermatitis, Malassezia overgrowth creates a different version of the same problem. The yeast produces inflammatory metabolites that trigger redness and scaling. Conventional antifungal treatment reduces the yeast population temporarily, but the underlying conditions that allowed overgrowth — altered sebum composition, reduced microbial diversity — often persist.²

Supporting the microbiome — rather than just suppressing its dysbiosis — addresses the ecosystem rather than the symptom.

What Does a Microbiome-Supportive Approach Look Like for Eczema-Prone Skin?

For atopic dermatitis, seborrheic dermatitis, and perioral dermatitis — the three types where the microbiome is most directly involved — a microbiome-supportive approach works alongside barrier repair rather than replacing it.

Barrier repair remains foundational. A compromised barrier is both a cause and consequence of microbiome dysbiosis — addressing it creates better conditions for microbial balance to be restored. Ceramides, beta glucan, and madecassoside are the core barrier repair ingredients in the ABC Microbiome Calming Lotion.

Botanical antimicrobials that work with the skin's ecosystem rather than against it are the next layer. The Bi-Om Complex — Coptis Japonica, Scutellaria Baicalensis, Houttuynia Cordata (Heartleaf), and Dictamnus Dasycarpus Root Extract — has documented antimicrobial activity against both S. aureus and Malassezia.³  This makes it relevant to both atopic and seborrheic dermatitis — addressing the two different microbiome imbalances driving the two most common types of inflammatory skin conditions.

Postbiotic support through Lactobacillus Ferment in the R+R Barrier Recovery Mist directly supports microbial balance on the skin's surface — creating conditions where beneficial bacteria can thrive and pathogenic species have less room to dominate.

Avoiding disruption is equally important. Fragrances, sulfates, high-percentage exfoliating acids, and — particularly for perioral dermatitis — topical steroids on the face can all disrupt the microbial environment in ways that worsen the conditions you're trying to improve.

For a complete guide to building a microbiome-supportive routine for eczema-prone skin:
Building a Steroid-Free Skincare Routine for Eczema-Prone Skin

FAQs About Types of Eczema and Dermatitis

Understanding Your Skin's Signals

Eczema is not one thing — and the more precisely you understand what type of dermatitis your skin is dealing with, the more effectively you can care for it. At Treats Lab, the Ato Biome Care philosophy is built around this kind of specificity. Not a blanket approach to sensitive skin, but a framework that starts with understanding what's actually happening in the skin — which microbial imbalance is present, what the barrier needs, and how to support both consistently over time. The Calm & Restore Duo was formulated with exactly this in mind: ingredients chosen for their specific relevance to the microbiome conditions driving the most common types of inflammatory skin conditions.

Footnotes:

1. Skin Microbiome Dynamics in Atopic Dermatitis: Understanding Host-Microbiome Interactions. Allergy Asthma Immunol Res. 2025. https://pmc.ncbi.nlm.nih.gov/articles/PMC11982640/
2. Composition of cutaneous bacterial microbiome in seborrheic dermatitis patients. PLOS ONE. 2021. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8143393/
3. Houttuynia cordata polysaccharides alleviate atopic dermatitis. International Journal of Biological Macromolecules. 2025. https://pubmed.ncbi.nlm.nih.gov/40393586/