Eczema (atopic dermatitis) and psoriasis are both chronic inflammatory skin conditions — but they arise from distinct immunological mechanisms, and treating them effectively requires understanding what is specifically happening beneath the surface of the skin in each case.
In functional medicine, the skin is never an isolated organ. It is a window into the immune system, the gut, the nervous system, and the overall inflammatory terrain of the body. Topical steroids and biologics can suppress what’s visible — but they don’t ask why the skin is in a state of chronic immune activation.
What Is Happening: Two Distinct Mechanisms
Eczema (Atopic Dermatitis) is driven primarily by a Th2-skewed immune response and a defective skin barrier. Mutations in the filaggrin gene (FLG) impair the production of proteins that maintain the skin’s structural integrity, allowing allergens, microbes, and irritants to penetrate. This triggers an exaggerated IgE-mediated and Th2 inflammatory response — producing the itching, weeping, and lichenification characteristic of chronic eczema. The skin microbiome is also significantly disrupted, with Staphylococcus aureus overgrowth amplifying inflammation and itch-scratch cycles.
Psoriasis involves a different immune axis — predominantly Th1 and Th17. Activated dendritic cells and T-cells drive keratinocytes (skin cells) to proliferate at 10 times their normal rate, producing the thick, silver-scaled plaques characteristic of psoriatic lesions. Psoriasis is now recognized as a systemic inflammatory disease, with significant associations with cardiovascular disease, psoriatic arthritis, metabolic syndrome, and inflammatory bowel disease. The skin manifestation is the visible tip of a much larger inflammatory iceberg.
Why Does This Immune Dysregulation Develop?
The gut-skin axis. This is perhaps the most clinically important frontier in both conditions. Intestinal dysbiosis and increased gut permeability create a chronic source of immune stimulation — microbial antigens and lipopolysaccharides crossing the gut barrier drive systemic Th2 skewing in eczema and Th17 activation in psoriasis. Patients with psoriasis have measurable gut dysbiosis, and psoriatic arthritis overlaps significantly with IBD in ways that point to a shared gut-immune pathway.
Food sensitivities and the IgG/IgE landscape. In eczema especially, delayed food reactions (IgG-mediated) to dairy, gluten, eggs, and soy frequently perpetuate skin inflammation below the threshold of classical allergy testing. Identifying and eliminating reactive foods produces dramatic improvement in many patients.
Psychological stress and the HPA-skin axis. Stress hormones directly modulate both skin barrier function and immune polarization. Corticotropin-releasing hormone (CRH) released at the skin level activates mast cells and promotes neurogenic inflammation — a key driver of the itch-scratch cycle in eczema and flares in psoriasis.
How We Approach These Conditions in Functional Medicine
For eczema, our focus is on restoring skin barrier function from within: omega-3 fatty acid optimization, vitamin D correction (strongly associated with barrier integrity), targeted elimination protocols based on food sensitivity testing, and gut microbiome restoration with specific strains — Lactobacillus rhamnosus GG has some of the strongest evidence for atopic disease.
For psoriasis, we work on suppressing the Th17/IL-23 axis through dietary intervention (a low-inflammatory, Mediterranean-style pattern has measurable effects on psoriatic severity), addressing the gut microbiome and intestinal permeability, optimizing vitamin D and zinc, and evaluating the cardiovascular and metabolic comorbidities that accompany systemic psoriatic inflammation.
Both conditions benefit from a thorough evaluation of toxic burden, stress physiology, and sleep quality — all of which modulate immune activation in ways that directly affect skin.
Your Skin Deserves a Root-Cause Investigation
If you’ve been managing flares with topical treatments and wondering why they keep returning, it’s time to look deeper.
Book your new patient appointment with Dr. Jamie Ahn today.
