Dermatology
What Causes Psoriasis?
Last reviewed: May 2026 · Haute MD Editorial Team
Psoriasis is an autoimmune condition in which the immune system — primarily T-cells — mistakenly attacks healthy skin cells, triggering an accelerated cycle of skin cell production. Normal skin cells are replaced every 28-30 days; in psoriasis, this cycle occurs in 3-4 days, causing cells to build up on the skin's surface as thick, silvery-scaled plaques.
What triggers psoriasis?
Common triggers include stress, infections (particularly streptococcal throat infections), certain medications (beta-blockers, lithium, antimalarials), skin injury (Koebner phenomenon), smoking, alcohol, and obesity. Genetics play a significant role — about one-third of people with psoriasis have a family history.
Types of psoriasis
Plaque psoriasis (most common) — red, scaly patches on elbows, knees, scalp, and lower back. Guttate psoriasis — small, drop-shaped lesions often triggered by strep throat. Inverse psoriasis — smooth, red patches in skin folds. Pustular psoriasis — pus-filled blisters. Erythrodermic psoriasis — widespread redness affecting most of the body.
How is psoriasis treated?
Mild psoriasis is treated with topical corticosteroids, vitamin D analogs, and tar preparations. Moderate-to-severe psoriasis requires phototherapy, systemic medications (methotrexate, cyclosporine, acitretin), or biologic medications (TNF inhibitors, IL-17 inhibitors, IL-23 inhibitors).
Frequently Asked Questions
Is psoriasis contagious?
No. Psoriasis is an autoimmune condition and cannot be spread through contact.
Can psoriasis affect joints?
Yes. Psoriatic arthritis develops in approximately 30% of people with psoriasis and causes joint pain, stiffness, and swelling. It requires treatment by both a dermatologist and rheumatologist.
Is psoriasis the same as eczema?
No. Both cause skin inflammation but have different immune mechanisms, appearances, and triggers. Psoriasis typically presents as thick, silvery plaques; eczema presents as itchy, weeping rashes.
What biologic medications treat psoriasis?
Biologics for psoriasis include adalimumab, secukinumab, ixekizumab, guselkumab, risankizumab, and others. They target specific inflammatory pathways and are highly effective for moderate-to-severe psoriasis.
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Dermatology · Bryn Mawr, PA
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