Psoriasis
An overactive immune system tells skin cells to grow many times faster than normal
Eczema
A leaky skin barrier and an overreactive immune system cause dry, intensely itchy patches that flare and calm down
Thick, silvery plaques on the outside of elbows and knees point to psoriasis. Very itchy, ill-defined patches in the inside creases — especially starting in childhood — point to eczema. Both are chronic, neither is contagious, and a dermatologist can usually tell them apart by looking.
Medical review pending
Review date to come
At a Glance
| Psoriasis | Eczema | |
|---|---|---|
| Looks like | Thick, raised plaques with sharp edges and silvery scale | Dry, rough patches with blurry edges; can ooze |
| Root cause | Immune signals (IL-17, IL-23) speed up skin growth | Weak barrier plus allergic-type (IL-4, IL-13) inflammation |
| Itch | Often itchy or sore | Intense, often worst at night |
| Typical spots | Outer elbows and knees, scalp, lower back | Inner elbows, behind knees, hands, neck, face |
| Usual start | Late teens to 30s, or 50–60 | Early childhood |
| Contagious? Same | No | No |
| Long-term? Same | Chronic, with flares | Chronic, with flares |
| Steroid creams help? Same | Yes | Yes |
Psoriasis
Thick patches with sharp edges, often on both sides of the body.
Flakes that lift off, sometimes leaving tiny bleeding points.
Most people itch, and plaques can sting or feel tight.
Plaques over joints may split and bleed.
Pitting, yellow-brown “oil drop” spots, lifting.
Morning stiffness or swollen fingers — tell your doctor.
Eczema
Often worst at night; the main symptom.
Skin feels tight and scaly.
Pink on light skin; brown, purple or gray on darker skin.
During bad flares or infection.
From long-term scratching (lichenification).
Itch wakes many people at night.
New skin cells form at the base of the epidermis and take about 28 days to rise, flatten and shed.
Normal cycle: about 4 weeks
In people with an inherited tendency, strep throat, stress or a skin injury wakes up immune “alarm” cells in the dermis.
Avoiding your triggers lowers flare risk
Alarm cells release IL-23, which drives T cells to pour out IL-17 and TNF. These signals tell skin cells to multiply.
Biologics block IL-17, IL-23 or TNF here
Skin cells divide so fast they reach the surface in 3–5 days instead of about 28. The epidermis thickens.
Vitamin D creams slow this turnover
Immature cells pile up as silvery scale, and widened blood vessels make the patch red and raised.
Steroids calm it; salicylic acid lifts scale
Ceramides and other fats seal the gaps between skin cells.
Moisturizers keep this layer intact
Water escapes and irritants slip in through the gaps.
Daily emollients refill the gaps
Immune cells release IL-4, IL-13 and IL-31 — the itch signals.
Dupilumab and other biologics block these signals
Scratching damages skin further and keeps the flare going.
Steroid and steroid-free creams calm the flare
Pink to red plaques with silvery-white scale.
Salmon to red-brown with silvery-white scale.
Violet to purple-brown with gray scale.
Dark brown or purple; marks may linger for months.
Pink to red, dry patches.
Red-brown patches with fine scale.
Purple-brown or gray; bumps around follicles.
Dark brown or ashy; light or dark marks after flares.
Either can start at any age.
| Psoriasis | Eczema | |
|---|---|---|
| Nails | Often pitted or lifting | Usually normal |
| Joints | Psoriatic arthritis in up to 30% | Not affected |
| Allergies & asthma | No special link | Often hay fever, asthma or food allergy |
Psoriasis
Help both; core for eczema.
BothShort courses for mild flares.
BothLifts thick scale.
Slows skin growth.
Eczema
Help both; core for eczema.
BothShort courses for mild flares.
BothSoothes itch.
Psoriasis
First-line for both.
BothSteroid-free; approved for both.
BothCalcipotriene.
Eczema
First-line for both.
BothSteroid-free; approved for both.
BothFace and eyelids.
Topical JAK.
Psoriasis
Short-term for severe flares.
BothPsoriasis pills.
Eczema
Short-term for severe flares.
BothJAK pills.
Psoriasis
Secukinumab, risankizumab…
Eczema
Dupilumab, tralokinumab, lebrikizumab.
Psoriasis
Helps both.
BothEczema
Helps both.
BothFinds contact allergies.
Thickness, edges, scale and exactly where patches sit.
Nails, scalp, joints, allergies, age of onset.
A skin scraping or small biopsy.
Yes, though it’s uncommon.
Usually eczema.
Photos help but can’t confirm a diagnosis.
Yes, for both.
Dermapedia is for education only and is not medical advice. It does not create a doctor–patient relationship. Always consult a qualified clinician about your own skin.