Psoriasis is a chronic immune-mediated disease that affects roughly 7.5 million American adults — about 3 percent of the population — according to the National Psoriasis Foundation. While most people picture the silvery-scaled plaques on elbows and knees, psoriasis is a systemic disease driven by overactive T-cell immunity that affects skin, joints, cardiovascular health, and mental health. The treatment landscape has been transformed in the past two decades by biologic therapies that achieve clear or near-clear skin in the majority of patients.
What Causes Psoriasis
Psoriasis results from an interplay of genetic susceptibility and environmental triggers. The disease involves T helper 17 (Th17) cells producing pro-inflammatory cytokines — IL-17, IL-23, and TNF-alpha — that drive rapid keratinocyte turnover. Skin cells normally take 28 to 30 days to mature and shed; in psoriatic skin, the process takes only 3 to 4 days, producing the characteristic thick scaly plaques.
Roughly 40 percent of patients have a family history. Strong genetic associations exist with HLA-Cw6 and other immune-related genes. Common triggers include streptococcal infection (especially in guttate psoriasis), skin trauma (Koebner phenomenon), stress, alcohol, smoking, certain medications (lithium, beta-blockers, antimalarials, abrupt steroid withdrawal), and obesity.
The Major Types
Plaque psoriasis (psoriasis vulgaris) accounts for about 80 to 90 percent of cases. It produces well-demarcated raised red plaques with silvery scale, usually on elbows, knees, scalp, and lower back, often symmetrically.
Guttate psoriasis appears as small drop-shaped lesions, often after streptococcal infection, especially in children and young adults. Inverse psoriasis affects skin folds — armpits, groin, under breasts — and is smooth rather than scaly. Pustular psoriasis features sterile pustules and can be localized (palms and soles) or generalized. Erythrodermic psoriasis, the rarest type, produces widespread red inflammation covering more than 75 percent of body surface and is a medical emergency.
About 50 percent of patients also have nail involvement — pitting, oil drop discoloration, onycholysis, or thickening. Per the Mayo Clinic, scalp involvement is also extremely common and can be the only manifestation in some patients.
Beyond the Skin: Comorbidities Matter
Psoriasis is associated with significantly elevated risk of multiple comorbidities. About 30 percent of patients develop psoriatic arthritis — typically 7 to 10 years after skin disease begins, though sometimes earlier. Our psoriatic arthritis guide covers that condition in detail. Other linked conditions include cardiovascular disease, metabolic syndrome, type 2 diabetes, inflammatory bowel disease, depression, and uveitis.
Patients with severe psoriasis have a roughly 50 percent higher risk of major cardiovascular events than the general population per epidemiological studies summarized in PMC. This is part of why psoriasis is now considered a systemic inflammatory disease rather than just a skin condition.
Topical Treatments
Mild to moderate disease is often controlled with topical therapy. Topical corticosteroids of varying potency remain the most-prescribed option. Calcipotriene (a vitamin D analog), tazarotene, calcineurin inhibitors (tacrolimus, pimecrolimus, used off-label), and the newer non-steroidal options roflumilast cream and tapinarof cream all play a role.
Salicylic acid keratolytics help with scale. Coal tar preparations, while less popular than they once were, remain effective and inexpensive. Combination products — fixed-dose calcipotriene plus betamethasone — improve adherence in scalp and body psoriasis.
Phototherapy and Systemic Therapy
Narrowband UVB phototherapy delivered 2 to 3 times weekly at a clinic or home unit is highly effective for moderate psoriasis. Excimer laser targets individual stubborn plaques. PUVA therapy (psoralen plus UVA) is used less often now due to long-term skin cancer risk.
Traditional systemic agents — methotrexate, cyclosporine, acitretin, and apremilast — remain options for moderate to severe disease. Methotrexate weekly at 7.5 to 25 mg with folate supplementation is widely used, costing roughly $30 to $80 per month. Apremilast (Otezla) is an oral PDE4 inhibitor priced around $3,000 monthly retail.
Biologics Have Transformed Outcomes
Biologic therapies target specific cytokines and have produced unprecedented response rates. TNF inhibitors (etanercept, adalimumab, infliximab, certolizumab) were the first wave. IL-12/23 inhibitors (ustekinumab) followed. The current generation — IL-17 inhibitors (secukinumab, ixekizumab, brodalumab, bimekizumab) and IL-23 inhibitors (guselkumab, risankizumab, tildrakizumab) — achieve PASI 90 (90 percent clearance) in 60 to 80 percent of patients in clinical trials.
Annual costs for biologics typically run $40,000 to $90,000 retail, though manufacturer copay assistance brings out-of-pocket costs to $5 to $50 per month for many commercially insured patients. Medicare patients face higher out-of-pocket costs in the absence of assistance programs. Our healthcare costs overview covers strategies for managing high-cost specialty medications.
Screening before biologic initiation typically includes TB testing (interferon-gamma release assay), hepatitis B and C, and assessment for infection risk and certain comorbidities. Live vaccines are generally avoided during biologic therapy.
Lifestyle Factors That Help
Weight loss meaningfully reduces psoriasis severity in patients who are overweight — even modest weight loss of 5 to 10 percent improves PASI scores in randomized trials. Smoking cessation reduces severity and improves response to treatment. Limiting alcohol, managing stress, and treating depression all improve outcomes.
Diet patterns matter. The Mediterranean diet has the most consistent evidence for inflammatory benefit; ketogenic, gluten-free, and other restrictive diets have weaker support outside of specific subgroups. Vitamin D supplementation may help patients with deficiency.
Regular skin care reduces flares. Daily moisturizing, avoiding harsh soaps, lukewarm rather than hot showers, and prompt treatment of minor cuts help prevent the Koebner phenomenon where new lesions appear at sites of skin trauma.
When to seek emergency care: Most psoriasis is not a medical emergency, but seek immediate care for sudden generalized redness covering most of the body (possible erythrodermic psoriasis), high fever with new pustular eruption (generalized pustular psoriasis), severe chest pain or stroke-like symptoms (psoriasis raises cardiovascular risk), or signs of serious skin infection — increasing redness, warmth, pus, fever, especially while on immunosuppressants. Erythrodermic and generalized pustular psoriasis can disrupt temperature regulation and fluid balance and require hospitalization.
When to See a Doctor
New persistent rashes, scalp scaling that does not resolve with antifungals, or thick plaques that do not respond to over-the-counter creams should be evaluated. Patients with established psoriasis should see dermatology when current therapy is no longer controlling disease, when joint pain develops (possible psoriatic arthritis), or when comorbidities like depression or cardiovascular symptoms emerge.
Many doctors recommend annual cardiovascular risk assessment for patients with moderate-to-severe psoriasis given the elevated risk. Mental health screening at every dermatology visit is increasingly standard. Our medical conditions overview covers the importance of integrated chronic disease management.
Frequently Asked Questions
Is psoriasis contagious?
No. Psoriasis is an immune-mediated disease, not an infection. It cannot be spread by touch, sharing towels, swimming pools, or any other means. The misconception causes considerable social stigma that is not supported by science.
Can psoriasis be cured?
There is no cure, but treatment has advanced dramatically. Modern biologics achieve clear or nearly clear skin in the majority of patients, and many people experience long periods of remission. Psoriasis can return at any time, particularly after triggers, but most people achieve good long-term control.
Does diet affect psoriasis?
Diet has a modest but real impact for some patients. Mediterranean-style eating has the best evidence. Weight loss in overweight patients consistently reduces severity. Specific foods that trigger flares vary by individual. Gluten-free diets help only patients with concomitant celiac disease, which occurs more often in psoriasis than chance.
Will my children get psoriasis?
Risk is elevated but not certain. If one parent has psoriasis, the lifetime risk for a child is about 10 to 15 percent. If both parents have psoriasis, the risk rises to 40 to 50 percent. Most children of psoriasis patients do not develop the disease.
The Bottom Line
Psoriasis is a systemic immune disease, not just a skin problem, and treating it well means managing both the visible plaques and the invisible cardiovascular, metabolic, and psychiatric risks that come with it. For mild disease, topicals and lifestyle measures suffice. For moderate-to-severe disease, modern biologics have produced response rates that would have seemed impossible 20 years ago. Connecting with a dermatologist comfortable with the full toolkit — including biologics — is the single most important step for anyone whose disease has not responded to over-the-counter approaches. Watching for joint symptoms and cardiovascular risk factors helps prevent the comorbidities that drive much of psoriasis’s long-term burden.