Psoriasis: Causes, Symptoms & Treatment

Psoriasis is a chronic autoimmune skin condition that causes the rapid buildup of skin cells, resulting in thick, red, scaly patches on the skin surface. Normally, skin cells grow and shed over about a month, but in psoriasis, this process is accelerated to just a few days, causing cells to pile up on the surface. Psoriasis is not contagious.

Psoriasis affects approximately 2-3% of the global population -- about 125 million people. It can develop at any age but most commonly appears between ages 15-35 and again around ages 50-60.

• Plaque psoriasis (~80%): Red, raised patches covered with silvery-white scales, commonly on elbows, knees, scalp, and lower back
• Guttate psoriasis: Small, drop-shaped spots, often triggered by streptococcal throat infection; more common in children
• Inverse psoriasis: Smooth, red patches in skin folds (armpits, groin, under breasts)
• Pustular psoriasis: White pustules surrounded by red skin
• Erythrodermic psoriasis: Widespread redness and shedding covering most of the body -- a medical emergency

Psoriasis results from an overactive immune system (T cells attacking healthy skin cells). Known triggers include:

• Stress (most common trigger)
• Skin injuries (cuts, scrapes, sunburn) -- the Koebner phenomenon
• Infections (especially streptococcal throat infections)
• Cold, dry weather
• Certain medications (beta-blockers, lithium, antimalarials, rapid steroid withdrawal)
• Smoking and heavy alcohol use
• Obesity

Treatment depends on severity (mild, moderate, or severe):

Mild disease -- topical therapies:

• Corticosteroid creams and ointments (first-line)
• Vitamin D analogues (calcipotriene)
• Topical calcineurin inhibitors (tacrolimus, pimecrolimus) for sensitive areas
• Coal tar preparations
• Salicylic acid (for scale removal)
• Moisturizers and emollients

Moderate to severe disease -- phototherapy:

• Narrowband UVB therapy (most common)
• PUVA (psoralen + UVA)

Moderate to severe disease -- systemic therapies:

• Traditional: Methotrexate, cyclosporine, acitretin, apremilast
• Biologic therapies (have revolutionized treatment):
  • TNF inhibitors (adalimumab, etanercept, infliximab)
  • IL-17 inhibitors (secukinumab, ixekizumab, brodalumab)
  • IL-23 inhibitors (guselkumab, risankizumab, tildrakizumab)
  • IL-12/23 inhibitor (ustekinumab)

See a dermatologist if you develop persistent red, scaly patches on your skin, if your symptoms worsen or spread, if you develop joint pain or stiffness, or if psoriasis significantly affects your quality of life or emotional well-being.