Psoriasis and Psoriatic Arthritis: Causes and Care
Author: Disabled World (DW)
Updated/Revised Date: 3 Aug 2026
Table of Contents:
Synopsis - Definition - About This Section - FAQs - Publications - Subtopics
Synopsis
A detailed guide to psoriasis and psoriatic arthritis, covering the causes, types, triggers, diagnosis, and treatment options including methotrexate therapy.
At a Glance
- 1 - Psoriasis is the most prevalent autoimmune disease in the United States.
- 2 - Plaque psoriasis is the most common form, affecting 85 to 90 percent of people with the condition.
- 3 - Methotrexate was first used to treat cancer before being found effective for psoriasis in the 1950s.
- 4 - Skin cell turnover normally takes about a month, but in psoriasis it can happen in only a few days, causing cells to pile up on the surface.
Topic Definition
- Psoriasis
Psoriasis is a chronic, immune-mediated skin disease marked by patches of thick, red, inflamed skin covered with silvery scales, which often itch or feel sore. It develops when the immune system mistakenly activates T cells, triggering inflammation and pushing skin cells to the surface far faster than normal - in days rather than the usual month - so the cells pile up before they can mature. These patches, often called plaques, most commonly appear on the elbows, knees, scalp, lower back, face, palms, and soles, but they can show up anywhere on the body and may also affect the fingernails and toenails. Psoriasis ranges widely in severity, from small localized spots to coverage of large areas of skin, and flare-ups can be set off by infections, stress, dry climates, and certain medications. Because it is a systemic condition rather than a purely surface problem, psoriasis is also linked to other health concerns and to a form of joint inflammation known as psoriatic arthritis.
Overview
Psoriasis is a debilitating skin condition that can affect the elbows, knees, scalp, lower back, face and indeed, any part of the body, including the genital area. It may also impact the fingernails and toenails, making them thick and discolored. Psoriasis is a chronic (long-lasting) skin disease of scaling and inflammation that affects 2 to 2.6 percent of the U.S. population, or between 5.8 and 7.5 million people.
- Psoriasis: A common, chronic, relapsing/remitting, immune-mediated systemic disease characterized by skin lesions including red, scaly patches, papules, and plaques, which usually itch. The skin lesions seen in psoriasis may vary in severity from minor localized patches to complete body coverage.
- Psoriatic arthritis: A form of arthritis that affects some people who have psoriasis, a condition that features red patches of skin topped with silvery scales. Most people develop psoriasis first and are later diagnosed with psoriatic arthritis, but the joint problems can sometimes begin before skin lesions appear.
Although the disease occurs in all age groups, it primarily impacts adults. It appears about equally in males and females. Psoriasis occurs when skin cells quickly rise from their origin below the surface of the skin and pile up on the surface before they have a chance to mature. Frequently, this movement (also called turnover) takes about a month, but in psoriasis it may occur in only a few days.
In its typical form, psoriasis results in patches of thick, red (inflamed) skin covered with silvery scales. These patches, which are sometimes referred to as plaques, typically itch or feel sore. They most often occur on the elbows, knees, other parts of the legs, scalp, lower back, face, palms, and soles of the feet, but they can occur on skin anywhere on the body.
How Does Psoriasis Affect Quality of Life?
Individuals with psoriasis may experience significant physical discomfort and some disability. Itching and pain can interfere with basic functions, such as self-care, walking, and sleep. Plaques on hands and feet can prevent individuals from working at certain occupations, playing some sports, and caring for family members or a home. The frequency of medical care is costly and can interfere with an employment or school schedule.
People with moderate to severe psoriasis may feel self-conscious about their appearance and have a poor self-image that stems from fear of public rejection and psycho-sexual concerns. Psychological distress can lead to significant depression and social isolation.
What Causes Psoriasis:
Psoriasis is a skin disorder. T cells help protect the body against infection and disease. Regarding psoriasis, T cells are put into action mistakenly and become so active that they trigger other immune responses, which lead to inflammation and to rapid turnover of skin cells. People with psoriasis may notice that there are times when their skin worsens, then improves.
Conditions that may cause flare-ups include infections, stress, and changes in climate that dry the skin. Furthermore, certain medicines, including lithium and beta-blockers, which are prescribed for high blood pressure, may trigger an outbreak or worsen the disease.
How Is Psoriasis Diagnosed?
Occasionally, doctors may find it difficult to diagnose psoriasis because it often looks like other skin diseases. It may be necessary to confirm a diagnosis by examining a small skin sample under a microscope. There are several forms of psoriasis. Some of these include:
- Plaque psoriasis: Skin lesions are red at the base and covered by silvery scales.
- Guttate psoriasis: Small, drop-shaped lesions appear on the trunk, limbs, and scalp. Guttate psoriasis is most typically triggered by upper respiratory infections (for example, a sore throat caused by streptococcal bacteria).
- Pustular psoriasis: Blisters of noninfectious pus appear on the skin. Attacks of pustular psoriasis may be triggered by medications, infections, stress, or exposure to certain chemicals.
- Inverse psoriasis: Smooth, red patches occur in the folds of the skin near the genitals, under the breasts, or in the armpits. The symptoms may be worsened by friction and sweating.
- Erythrodermic psoriasis: Widespread reddening and scaling of the skin may be a reaction to severe sunburn or to taking corticosteroids (cortisone) or other medications. It can also be caused by a prolonged period of increased activity of psoriasis that is poorly controlled.
- Psoriatic arthritis: Joint inflammation that produces symptoms of arthritis in patients who have or will develop Psoriasis.
Blood tests conducted for this condition may rule out other conditions such as gout or rheumatoid arthritis. There is a particular antibody normally present in rheumatoid arthritis that is not present in psoriatic arthritis. These tests will often also show elevated erythrocyte sedimentation rate or ESR which measures inflammation. They frequently show mild anemia and elevated levels of uric acid.
Methotrexate
This medication has been used very successfully in the treatment of psoriasis and psoriatic arthritis. Methotrexate works by binding to and inhibiting an enzyme involved in the rapid growth of cells, thus slowing down the rate of skin cell growth. It was originally used in the treatment of cancer but was discovered in the 1950s to be effective in the treatment of psoriasis and was eventually approved for use in this condition in the 1970s.
Methotrexate is generally well tolerated in small doses, but it does potentially have several side effects. For this reason, it is imperative that a patient on this drug follows the instructions of their physician prudently. People taking this medication need to have regular blood tests to be sure that the body is processing the drug safely and not creating other problems, particularly in the liver.
Psoriasis Facts and Statistics
- People with advanced HIV/AIDS often exhibit psoriasis.
- Plaque - Psoriasis vulgaris (also known as chronic stationary psoriasis or plaque-like psoriasis) is the most common form and affects 85% to 90% of people with psoriasis.
- The causes of psoriasis are not fully understood. It is not purely a skin disorder and can have a negative impact on many organ systems. Psoriasis has been associated with an increased risk of certain cancers, cardiovascular disease, and other immune-mediated disorders such as Crohn's disease and ulcerative colitis.
- Additional types of psoriasis impacting the skin include inverse psoriasis, guttate psoriasis, oral psoriasis, and seborrheic-like psoriasis.
- While no cure is available for psoriasis, many treatment options exist. Topical agents are typically used for mild disease, phototherapy for moderate disease, and systemic agents for severe disease.
- Psoriatic arthritis is a form of chronic inflammatory arthritis that has a highly variable clinical presentation and frequently occurs in association with skin and nail psoriasis.
- Anyone can get psoriasis. It occurs mostly in adults, but children can also get it. Men and women seem to have equal risk.
- Psoriasis is the most prevalent autoimmune disease in the U.S.
- Psoriasis often appears between the ages of 15 and 25, but can develop at any age.
- Psoriatic arthritis usually develops between the ages of 30 and 50, but can develop at any age.
- Psoriasis prevalence in African Americans is 1.3 percent, compared to 2.5 percent of Caucasians.
- Studies show that between 10 and 30 percent of people with psoriasis also develop psoriatic arthritis.
- According to current studies, as many as 7.5 million Americans, approximately 2.2 percent of the population, have psoriasis.
- According to the World Psoriasis Day consortium, 125 million people worldwide, 2 to 3 percent of the total population, have psoriasis.
Frequently Asked Questions
Is psoriasis contagious?
No, psoriasis is not contagious and cannot be spread through touch, shared items, or close contact, because it is an immune-mediated condition rather than an infection.
Can psoriasis be cured?
There is no known cure for psoriasis, but many treatments can control symptoms, including topical agents for mild cases, phototherapy for moderate cases, and systemic medicines for severe disease.
What foods can trigger psoriasis flare-ups?
Triggers vary by person, but some people find that alcohol, red meat, processed foods, and other inflammatory foods worsen symptoms, while a balanced diet may help some individuals manage flare-ups.
Is psoriasis hereditary?
Psoriasis can run in families, and having a close relative with the condition increases the risk, though genetics combine with immune and environmental factors to determine who develops it.
Can children get psoriasis?
Yes, children can develop psoriasis, although it occurs mostly in adults and often first appears between the ages of 15 and 25, with men and women sharing roughly equal risk.
Does stress make psoriasis worse?
Stress is a well recognized trigger that can cause psoriasis to flare or worsen, so managing stress through healthy habits and support can be an important part of overall care.
What is the difference between psoriasis and eczema?
Psoriasis produces thick, well defined red patches topped with silvery scales, while eczema tends to cause intensely itchy, inflamed, and sometimes weeping skin, and the two conditions have different underlying causes.
Curated and edited by Ian C. Langtree, Founder & Editor-in-Chief, Disabled World. This section is maintained by the Disabled World editorial team.
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