Psoriasis

Psoriasis is a chronic skin condition that causes thick, scaly patches to develop on the skin. While there’s no cure, many effective treatments can help manage symptoms and improve quality of life.

Table of contents

• What is psoriasis?
• Types of psoriasis
• What does psoriasis look like?
• Where does psoriasis appear?
• What causes psoriasis?
• Common triggers
• Related health conditions
• How is psoriasis diagnosed?
• Treatment options
• Living with psoriasis

What is psoriasis?

Psoriasis is a skin disease that causes a rash with itchy, scaly patches. It is a chronic condition, which means it lasts a long time and has no cure^[1]. The condition affects millions of people worldwide—an estimated 60 million people have psoriasis globally, and about 1.52% to 3% of the population is affected in the UK and US^[5][2].

Psoriasis is an autoimmune condition that causes inflammation in your skin. This means your immune system, which normally protects your body from disease and infection, mistakenly attacks healthy skin cells^[2][4]. This overactive immune response speeds up skin cell growth dramatically.

Normally, skin cells are made and replaced every 3 to 4 weeks. In people with psoriasis, this process only takes about 3 to 7 days^[4][3]. Instead of shedding naturally, the skin cells pile up on the surface of the skin, creating the thick, scaly patches known as plaques^[3].

The condition tends to go through cycles, flaring for a few weeks or months, then subsiding for a while or going into remission^[1]. Psoriasis affects both men and women equally and can start at any age, though it most commonly develops in adults between ages 20 and 30 or between ages 50 and 60^[4][5].

Types of psoriasis

There are several types of psoriasis, each with distinct characteristics^[2][3]:

• Plaque psoriasis: This is the most common type, affecting about 80% to 90% of people with psoriasis. It causes dry, raised skin patches covered with thick scales. These patches typically appear red or pink on lighter skin and darker brown or purple on darker skin.
• Guttate psoriasis: This type appears as small, red, drop-shaped scaly spots. It’s more common in children and young adults and may appear after a sore throat caused by a streptococcal infection.
• Inverse psoriasis: This type appears in skin folds, such as under the breasts, in the armpits, or around the genitals. It causes smooth patches of inflamed skin and thin plaques without scales.
• Pustular psoriasis: This form has small, pus-filled bumps on top of plaques. The pustules are not infectious.
• Erythrodermic psoriasis: This is a severe type that affects a large area (more than 90%) of the skin. It causes widespread skin discoloration and skin shedding.
• Sebopsoriasis: This type typically appears on the face and scalp as bumps and plaques with a greasy, yellow scale. It’s a cross between psoriasis and seborrheic dermatitis.
• Nail psoriasis: This affects the fingernails and toenails, causing skin discoloration, pitting, and changes to the nails.

It is possible to have more than one type of psoriasis at a time and more than one type throughout a lifetime^[3].

What does psoriasis look like?

The main symptom of psoriasis is plaques—thick areas of discolored skin covered with scales^[2][3]. These plaques appear as:

• A rash or raised area of thick skin
• Discolored skin (the color varies depending on your natural skin tone)
• Scaly or flaky patches that shed easily

On lighter skin, plaques typically appear as raised, red patches covered with a silvery white buildup of dead skin cells or scale. On darker skin tones, the plaques may appear darker and thicker, with more of a purple, grayish, or darker brown color^[3].

An early sign of psoriasis is small bumps. The bumps grow, and scales form on top^[2]. If you scratch the rash, the scales may tear away from your skin, which can cause bleeding.

Other common symptoms include^[3]:

• Itching, irritation, burning, or stinging
• Dry skin that may crack or bleed
• Flaking of dead skin
• Changes to fingernails and toenails

Symptoms can range from mild to severe. For some people, psoriasis is just a minor irritation, but for others it can have a significant impact on their quality of life^[4].

Where does psoriasis appear?

A psoriasis rash can show up anywhere on your skin^[2]. Psoriasis is most common on^[1][3]:

• Elbows and knees
• Scalp
• Lower back
• Face and inside of the mouth
• Fingernails and toenails
• Genitals
• Palms and feet
• Skin folds

In most people, psoriasis covers a small area of their skin. In severe cases, the plaques connect and cover a large area of the body^[2]. Certain areas of the body are called high-impact sites, and psoriasis in these locations can have an increased negative impact on quality of life, regardless of the total area affected^[3].

What causes psoriasis?

The exact cause of psoriasis is not fully understood, but researchers believe it involves a combination of factors^[3][7]:

Immune system problems: In people with psoriasis, the immune system attacks healthy skin cells by mistake. A type of white blood cell called a T-cell normally travels through the body to detect and fight invading germs, such as bacteria. But in people with psoriasis, T-cells start to attack healthy skin cells^[7]. This causes the deepest layer of skin to produce new skin cells more quickly than usual.

Genetics: Psoriasis has a major genetic component, with heritability estimated to be 60% to 90%^[5]. If one twin has psoriasis, the other twin is three times more likely to be affected if the twins are identical than if they are nonidentical^[6]. If you have a close relative with psoriasis, you may be more likely to develop the condition^[7]. However, having these genes does not necessarily mean you’ll develop psoriasis—it appears that environmental factors also play a role.

Environmental factors: Usually, something triggers psoriasis in people who have a genetic predisposition to the condition, causing symptoms to appear or worsen^[3].

Psoriasis is not contagious. It cannot be spread from person to person through touch or close contact^[3][4].

Common triggers

Many people’s psoriasis symptoms start or become worse because of a certain event, known as a trigger. Triggers vary from person to person^[3][7]. Common psoriasis triggers include:

• Injury to the skin: Cuts, scrapes, insect bites, or sunburn can trigger psoriatic skin changes at that spot. This is known as the Koebner phenomenon^[6][7].
• Infections: Throat infections, particularly streptococcal throat infections, can trigger guttate psoriasis, especially in children and young adults^[7].
• Stress: High stress levels can trigger flare-ups or make existing psoriasis worse.
• Certain medications: Some medicines can trigger or worsen psoriasis, including lithium (used to treat bipolar disorder), some antimalarial medicines, anti-inflammatory medicines like ibuprofen, and ACE inhibitors (used to treat high blood pressure)^[7].
• Smoking and alcohol: Smoking and drinking excessive amounts of alcohol can trigger psoriasis or make it worse^[7].
• Hormonal changes: Particularly in women, hormonal changes during puberty and menopause can trigger psoriasis^[7].
• Other immune disorders: Conditions such as HIV can cause psoriasis to flare up or appear for the first time^[7].
• Weather: Cold, dry weather can worsen symptoms.

Knowing your triggers may help you avoid flare-ups^[7].

Related health conditions

Psoriasis is associated with several related health conditions, known as comorbidities^[3][5]. Recognition and management of these conditions is an essential part of holistic care for people with psoriasis.

Psoriatic arthritis: This is a type of arthritis that causes joint pain and swelling. About 1 in 3 people diagnosed with psoriasis will also develop psoriatic arthritis due to inflammation^[2]. It causes tenderness, pain, and swelling in the joints and connective tissue, as well as stiffness. It can affect any joint in the body but often affects the hands, feet, knees, neck, spine, and elbows^[4]. Early treatment of psoriatic arthritis can reduce damage to your joints.

Cardiovascular disease: People with psoriasis have a slightly higher risk of developing heart disease and related conditions than the general population^[5]. As a disease of systemic inflammation, psoriasis is associated with increased rates of cardiovascular complications.

Metabolic diseases: There is an increased risk of conditions like type 2 diabetes and obesity. Obese patients with psoriasis are more likely to have more severe psoriasis^[5].

Liver disease: Hepatic (liver-related) disease is more common in people with psoriasis^[5].

Mental health conditions: The effect that psoriasis can have on physical appearance means low self-esteem and anxiety are common among people with the condition. This can lead to depression, especially if the psoriasis gets worse^[4]. People with psoriasis are more likely to become depressed^[15].

How is psoriasis diagnosed?

A healthcare provider can often diagnose psoriasis based on the appearance of your skin^[4][8]. Your provider will ask questions about your health and examine your skin, scalp, and nails.

A healthcare provider will take several factors into consideration when making a diagnosis^[3]:

• The appearance of the skin (psoriasis patches may be thick, raised plaques or fine scaling)
• The location of psoriasis (there are areas on the body that are more common for psoriasis to appear)
• Whether the skin is itchy

In rare cases, a small sample of skin called a biopsy will be sent to the laboratory for examination under a microscope^[4][8]. This helps determine the type of psoriasis and rule out other skin disorders. A biopsy is seldom required for diagnosis^[12].

You may be referred to a specialist in diagnosing and treating skin conditions (a dermatologist) if your doctor is uncertain about your diagnosis or if your condition is severe^[4].

If your doctor suspects you have psoriatic arthritis, you may be referred to a doctor who specializes in arthritis (a rheumatologist). You may have blood tests to rule out other conditions, such as rheumatoid arthritis, and X-rays of the affected joints may be taken^[4].

Treatment options

There’s no cure for psoriasis, but a range of treatments can improve symptoms and the appearance of skin patches^[4][3]. The goal of treatment is to stop skin cells from growing so quickly and to remove scales^[8]. Treating psoriasis can help improve symptoms as well as lower the risk of developing related conditions such as psoriatic arthritis, heart disease, obesity, diabetes, and depression^[3].

Which treatments you use depends on how severe the psoriasis is and how responsive it has been to previous treatment. You might need to try different treatments or a combination of treatments before you find an approach that works^[8]. Your doctor will ask you about how much the condition is affecting your everyday life^[4].

Treatments fall into three main categories^[10][11]:

Topical treatments: These are creams and ointments applied to the skin. They are usually the first treatment used for mild to moderate psoriasis^[4][10]. Some people find that topical treatments are all they need to control their condition, although it may take up to 6 weeks before there’s a noticeable effect^[10].

• Corticosteroids (steroid creams): These are the most frequently prescribed medications for treating mild to moderate psoriasis. They reduce inflammation and slow the production of skin cells. They range in strength from mild to very strong and are available as oils, ointments, creams, lotions, gels, foams, sprays, and shampoos^[8][10].
• Vitamin D analogues: These creams slow the production of skin cells and have an anti-inflammatory effect. Examples include calcipotriol, calcitriol, and tacalcitol^[10].
• Emollients: These are moisturizing treatments that reduce water loss and help reduce itching and scaling^[10].
• Coal tar: A thick, heavy oil that can reduce scales, inflammation, and itchiness^[10].
• Other topical treatments: Including calcineurin inhibitors and dithranol^[10].

Phototherapy: This involves exposing your skin to certain types of ultraviolet light^[4][10]. The two main types are narrowband ultraviolet B radiation (NB-UVB) and psoralen and ultraviolet A radiation (PUVA)^[5].

Systemic treatments: These are oral or injected medicines that work throughout the whole body^[10]. They are used for more severe cases or when other treatments are not effective. Systemic treatments include:

• Standard systemic agents: Including methotrexate, ciclosporin, and acitretin^[5].
• Biologic therapies: These are targeted treatments that work by blocking specific parts of the immune system. They include tumor necrosis factor (TNF) inhibitors, interleukin (IL)-17 inhibitors, and IL-23 inhibitors^[5][8].
• Small molecule inhibitors: Including dimethyl fumarate and apremilast^[5].

Many patients seek initial evaluation and treatment from their primary care providers, and primary care physicians are well positioned to provide diagnosis and initiate treatment of psoriasis, particularly with topical therapies^[12]. More severe and refractory cases may warrant referral to a dermatologist for further evaluation and possible systemic therapy^[12].

Living with psoriasis

Beyond the physical symptoms, psoriasis has an extensive emotional and psychosocial effect on patients, affecting social functioning and interpersonal relationships^[5][12]. Many people with psoriasis experience low self-esteem because of the effect the condition has on their appearance.

Self-care strategies: Self-care is an essential part of daily life with psoriasis^[16]. Important self-care strategies include:

• Keep your skin moist: Use thick creams or lotions to seal in water after bathing. This can help with scaling and reduce itchiness^[17].
• Stay with your treatment plan: Make prescribed creams or ointments part of your daily routine, even when symptoms improve^[17].
• Avoid triggers: Once you know your triggers, you can find ways to prevent flare-ups^[17].
• Manage stress: Stress is a common trigger for psoriasis flares. Consider meditation, exercise, or seeking help from a mental health professional^[15][19].
• Bathe with care: Use lukewarm water, avoid hot showers, and add non-fragrance salts or finely ground oatmeal to bathwater^[17].

Healthy lifestyle: Regular exercise and a healthy diet are recommended for everyone with psoriasis^[16]. If you have psoriasis, your doctor may suggest changes to your lifestyle to help reduce symptoms, including stopping smoking, cutting down on alcohol, and losing weight if you are overweight or obese^[16]. Some people with psoriasis have found that an anti-inflammatory diet may help reduce symptoms^[20].

Mental health support: If you have psoriasis and concerns about your physical and mental wellbeing, speak to your healthcare provider. They can offer advice and further treatment if necessary^[4]. It’s important to look for symptoms of depression and seek treatment if you need it. There are also support groups for people with psoriasis where you can speak to other people with the condition^[4].

Although psoriasis is a lifelong condition, symptoms may resolve and recur throughout the lifetime^[3]. While there is no cure, treatments today are more effective than ever before, and research into new treatments continues^[3].