Psoriasis: Types, Symptoms, Causes, Triggers and Treatment

Psoriasis is a chronic inflammatory disease that mainly affects the skin but can also affect the nails and joints.

It occurs when the immune system becomes overactive and causes skin cells to build up much faster than normal.

This can result in areas of inflamed, thickened and sometimes scaly skin.

Psoriasis is not contagious.

You cannot catch psoriasis by:

• touching someone who has it,
• hugging or kissing,
• sharing food,
• swimming together,
• or using the same household items.

Psoriasis can occur at any age and affects people around the world.

There is currently no cure, but modern treatments can control the disease effectively for many people.

What Does Psoriasis Look Like?

Psoriasis can look different from one person to another.

Common features can include:

• well-defined patches or plaques of inflamed skin,
• scaling,
• itching,
• burning,
• soreness,
• dry or cracked skin,
• and sometimes bleeding.

On lighter skin tones, psoriasis plaques often appear red or pink.

On darker skin tones, inflammation may appear:

• purple,
• violet,
• dark brown,
• grey,
• or deeper in colour than the surrounding skin.

Scale may appear white, silver or grey.

Changes in skin colour can remain after a psoriasis lesion has improved, particularly in darker skin tones.

Because psoriasis can look different across skin colours, professional diagnosis can be useful when the cause of a rash is uncertain.

Where Does Psoriasis Occur?

Psoriasis can affect almost any part of the body.

Common areas include:

• scalp,
• elbows,
• knees,
• lower back,
• trunk,
• hands,
• feet,
• skin folds,
• and nails.

It can also affect sensitive areas such as the face and genitals.

Some people have only a few small patches, while others have extensive disease.

Is Psoriasis an Autoimmune Disease?

Psoriasis involves abnormal immune-system activity and is commonly described as an immune-mediated inflammatory disease.

Scientists believe that both genetic and environmental factors contribute.

The immune system sends inflammatory signals that accelerate the normal cycle of skin-cell production.

Skin cells then accumulate at the surface instead of being shed normally.

This contributes to the characteristic plaques and scaling.

What Causes Psoriasis?

There is no single known cause.

Psoriasis appears to develop through an interaction between:

• genetics,
• the immune system,
• and environmental or internal triggers.

Having a genetic predisposition does not mean that a person will definitely develop psoriasis.

Likewise, someone can develop psoriasis without knowing of another family member who has it.

Does Psoriasis Run in Families?

Psoriasis can run in families.

Having relatives with psoriasis can increase a person's likelihood of developing the condition.

However, genetics alone do not determine who develops psoriasis.

Multiple genes and environmental factors appear to be involved.

Different Types of Psoriasis

Psoriasis is not one uniform condition.

Several clinical forms exist, and a person can experience more than one type during their lifetime.

The main types include:

• plaque psoriasis,
• guttate psoriasis,
• inverse psoriasis,
• pustular psoriasis,
• and erythrodermic psoriasis.

Nail psoriasis can also occur independently or alongside skin psoriasis.

1. Plaque Psoriasis

Plaque psoriasis is the most common form.

It causes clearly defined areas of thickened, inflamed skin called plaques.

These plaques may be covered with white, silver or grey scale.

Common locations include:

• elbows,
• knees,
• scalp,
• and trunk.

Plaques may:

• itch,
• burn,
• feel sore,
• crack,
• or bleed.

The severity can range from a few small plaques to extensive disease.

2. Guttate Psoriasis

Guttate psoriasis typically causes numerous small, drop-shaped lesions.

It often affects the:

• trunk,
• arms,
• and legs.

It occurs more commonly in children and younger adults than some other forms of psoriasis.

Guttate psoriasis can sometimes appear after an infection, particularly a streptococcal throat infection.

Some cases resolve, while others can recur or later develop into chronic plaque psoriasis.

3. Inverse Psoriasis

Inverse psoriasis affects skin folds.

Common locations include:

• armpits,
• groin,
• under the breasts,
• between the buttocks,
• and other areas where skin touches skin.

Unlike typical plaque psoriasis, inverse psoriasis often looks:

• smooth,
• shiny,
• and inflamed,

with relatively little scaling.

Heat, moisture and friction can make symptoms worse.

Because fungal infections and other skin conditions can look similar, professional diagnosis may be necessary.

4. Pustular Psoriasis

Pustular psoriasis causes pus-filled bumps or pustules surrounded by inflamed skin.

The pus is not usually caused by a bacterial infection and is not contagious.

Pustular psoriasis may be limited to areas such as:

• palms,
• soles,
• or fingertips.

Alternatively, it can occur widely across the body.

Generalized pustular psoriasis can be a serious medical condition and may require urgent hospital treatment.

A person who develops widespread pustules accompanied by fever or severe illness should seek urgent medical care.

5. Erythrodermic Psoriasis

Erythrodermic psoriasis is rare but potentially life-threatening.

It causes widespread inflammation and redness or significant colour change affecting most of the body's skin.

Symptoms may include:

• extensive peeling,
• severe itching,
• pain,
• changes in body temperature,
• rapid heartbeat,
• swelling,
• and feeling seriously unwell.

Suspected erythrodermic psoriasis requires urgent medical assessment.

Severe widespread inflammation can interfere with the body's ability to regulate temperature and fluid balance.

Nail Psoriasis

Psoriasis can affect fingernails and toenails.

Changes may include:

• tiny pits in the nail surface,
• discolouration,
• thickening,
• crumbling,
• changes in nail shape,
• and separation of the nail from the nail bed.

Nail psoriasis can sometimes resemble a fungal nail infection.

A healthcare professional may need to distinguish between the two because treatments are different.

Nail psoriasis can also be associated with psoriatic arthritis.

Scalp Psoriasis

Scalp psoriasis can range from mild scaling to thick plaques covering large areas of the scalp.

It may extend beyond the hairline.

Symptoms can include:

• itching,
• scaling,
• dryness,
• soreness,
• and temporary hair shedding related to scratching or inflammation.

Scalp psoriasis is not simply dandruff, although the two conditions can sometimes look similar.

Special shampoos, solutions, foams or other treatments may be recommended depending on severity.

What Is a Psoriasis Flare?

Psoriasis symptoms often come and go.

A period when symptoms become more active or severe is commonly called a flare or flare-up.

Some people experience periods when their psoriasis is barely noticeable followed by periods when it becomes much more active.

Triggers differ significantly between individuals.

Something that triggers one person's psoriasis may have no effect on another person.

Common Psoriasis Triggers

Potential triggers or factors that can worsen psoriasis include:

• skin injuries,
• infections,
• stress,
• smoking,
• heavy alcohol consumption,
• certain medicines,
• and changes in weather or climate.

Not everyone has identifiable triggers.

Keeping track of when flares occur can sometimes help identify individual patterns.

Skin Injury and the Koebner Phenomenon

Psoriasis can sometimes develop at the site of skin injury.

This is known as the Koebner phenomenon.

Possible triggers include:

• cuts,
• scratches,
• burns,
• severe sunburn,
• tattoos,
• and other skin trauma.

This does not mean that every minor injury causes psoriasis.

It occurs primarily in susceptible individuals.

Infections

Certain infections can trigger or worsen psoriasis.

A well-known example is streptococcal throat infection, which can precede guttate psoriasis.

Other infections can also influence psoriasis in some people.

Treating an infection does not necessarily cure psoriasis, but suspected infections should receive appropriate medical assessment.

Stress

Psychological stress can contribute to psoriasis flares in some people.

Psoriasis itself can also cause stress because visible skin disease can affect:

• confidence,
• relationships,
• work,
• sleep,
• and social activities.

This can create a difficult cycle in which psoriasis increases stress and stress contributes to further symptoms.

Stress-management approaches such as:

• adequate sleep,
• physical activity,
• relaxation techniques,
• counselling,
• and psychological support

may help some people manage the emotional burden.

They should complement rather than replace appropriate psoriasis treatment.

Smoking

Smoking is associated with psoriasis and can worsen disease in some people.

Stopping smoking has broad health benefits extending far beyond psoriasis.

Anyone who smokes and wants to quit can ask a healthcare professional about evidence-based smoking-cessation support.

Alcohol

Heavy alcohol consumption can be associated with more difficult-to-control psoriasis and may interact with some psoriasis medicines.

People taking systemic psoriasis medication should ask their healthcare professional whether alcohol is safe with their particular treatment.

Medicines That Can Trigger Psoriasis

Certain medicines can trigger or worsen psoriasis in susceptible people.

Examples reported in medical literature include some:

• beta blockers,
• lithium,
• antimalarial medicines,
• and other medications.

However:

Do not stop a prescribed medicine because you think it is worsening your psoriasis.

Suddenly stopping some medicines can be dangerous.

Speak with the healthcare professional who prescribed the medicine so that the risks and alternatives can be considered safely.

Does Sunlight Help Psoriasis?

Ultraviolet light can improve psoriasis in some people, which is why controlled medical phototherapy is an established treatment.

However, this does not mean that unlimited sun exposure is safe.

Sunburn can:

• damage the skin,
• increase skin-cancer risk,
• and sometimes trigger psoriasis through skin injury.

Medical phototherapy uses controlled ultraviolet exposure under professional supervision and is different from simply spending long periods in strong sunlight.

Is Dry Skin a Cause of Psoriasis?

Dry skin does not cause psoriasis.

However, dryness can make existing psoriasis:

• itchier,
• more uncomfortable,
• and more likely to crack.

Regular use of an appropriate moisturizer or emollient can help maintain the skin barrier and reduce dryness.

Can Psoriasis Be Prevented?

There is currently no proven way to guarantee that psoriasis will never develop.

Although psoriasis cannot always be prevented, people who already have the condition may be able to reduce some triggers and manage flare-ups with appropriate treatment and self-care.

A useful goal is:

• controlling existing disease,
• reducing known triggers,
• protecting the skin,
• and treating flares appropriately.

Some people can significantly reduce the frequency or severity of their flares through treatment and trigger management.

How Is Psoriasis Diagnosed?

Psoriasis is usually diagnosed by examining:

• the skin,
• scalp,
• and nails.

A healthcare professional may also ask about:

• symptoms,
• family history,
• previous skin problems,
• medicines,
• recent infections,
• and joint symptoms.

There is no single blood test that confirms ordinary psoriasis.

Occasionally, a small skin sample called a biopsy may be taken if the diagnosis is uncertain or another condition needs to be excluded.

Conditions That Can Resemble Psoriasis

Several skin conditions can resemble psoriasis.

These include:

• eczema,
• fungal infections,
• seborrhoeic dermatitis,
• pityriasis rosea,
• and other inflammatory skin disorders.

Self-diagnosis from photographs alone can therefore be unreliable.

A persistent or unexplained rash should be professionally assessed.

How Is Psoriasis Treated?

Treatment depends on:

• the type of psoriasis,
• severity,
• areas of the body affected,
• age,
• other health conditions,
• previous treatments,
• and how much psoriasis affects everyday life.

There is no single treatment that works best for everyone.

Treatment generally falls into three broad categories:

• topical treatments,
• phototherapy,
• and systemic treatments.

Topical Treatments

Topical treatments are applied directly to the skin.

They are commonly used for mild or localized psoriasis and can also be combined with other treatments.

Depending on the location and severity, treatment may include:

• topical corticosteroids,
• vitamin D analogues,
• topical retinoids,
• calcineurin inhibitors for selected areas,
• salicylic acid,
• coal tar preparations,
• and moisturizers or emollients.

Some of these treatments require a prescription.

Strong topical steroids should be used according to professional instructions because inappropriate long-term use can cause side effects.

Moisturizers and Emollients

Moisturizers do not cure psoriasis, but they can help:

• reduce dryness,
• soften scale,
• reduce cracking,
• and make the skin more comfortable.

Thicker creams or ointments are often more effective for very dry skin than thin lotions.

Fragrance-free products may be preferable for sensitive skin.

Phototherapy

Phototherapy exposes affected skin to carefully controlled ultraviolet light.

One commonly used treatment is narrowband UVB phototherapy.

Phototherapy may be considered when:

• topical treatments have not provided sufficient control,
• psoriasis covers larger areas,
• or the disease is more severe.

Phototherapy should be delivered according to professional guidance because excessive ultraviolet exposure can damage the skin.

Commercial tanning beds are not a safe substitute for medical phototherapy.

Systemic Medicines

Moderate-to-severe psoriasis may require medicines that work throughout the body.

Depending on the individual and what is available in their country, these may include:

• methotrexate,
• ciclosporin,
• retinoids,
• oral targeted medicines,
• and biologic medicines.

These treatments can be highly effective but may require:

• blood tests,
• infection screening,
• monitoring,
• and assessment for possible side effects.

Treatment should be prescribed and monitored by an appropriately qualified healthcare professional.

Biologic Medicines

Biologics are targeted medicines that affect specific parts of the immune system involved in psoriasis.

They have transformed treatment for many people with moderate-to-severe psoriasis and psoriatic arthritis.

Different biologics target inflammatory pathways such as:

• tumour necrosis factor (TNF),
• interleukin-17,
• interleukin-23,
• and related pathways.

The most appropriate medicine depends on:

• psoriasis severity,
• joint involvement,
• other health conditions,
• previous treatments,
• pregnancy considerations,
• infection risk,
• and local availability.

What Is Psoriatic Arthritis?

Psoriasis is not always limited to the skin.

Some people develop psoriatic arthritis, an inflammatory condition affecting joints and areas where tendons and ligaments attach to bone.

Symptoms can include:

• painful joints,
• swollen joints,
• morning stiffness,
• swollen fingers or toes,
• heel pain,
• back or neck stiffness,
• and fatigue.

Sometimes arthritis develops before obvious psoriasis appears.

Why Psoriatic Arthritis Matters

Untreated psoriatic arthritis can cause permanent joint damage.

People with psoriasis should tell their healthcare professional if they develop new:

• joint pain,
• swelling,
• stiffness,
• heel pain,
• or swollen fingers or toes.

Early diagnosis and appropriate treatment can help protect the joints.

Psoriasis and Overall Health

Psoriasis is increasingly understood as more than a skin condition.

People with psoriasis—particularly more severe disease—can have increased rates of certain other health problems.

These may include:

• psoriatic arthritis,
• cardiovascular disease,
• obesity,
• diabetes,
• anxiety,
• and depression.

This does not mean everyone with psoriasis will develop these conditions.

It does mean that overall health should be considered as part of psoriasis care.

Psoriasis and Mental Health

Visible psoriasis can significantly affect emotional wellbeing.

People may experience:

• embarrassment,
• low confidence,
• social isolation,
• anxiety,
• depression,
• or difficulties with relationships.

These effects are genuine health concerns and should not be dismissed as cosmetic problems.

Anyone struggling emotionally because of psoriasis should discuss this with a healthcare professional.

Living With Psoriasis

Alongside prescribed treatment, several everyday measures may help.

Moisturize regularly

Keeping skin moisturized can reduce dryness, scaling and cracking.

Avoid scratching

Scratching can damage skin and sometimes worsen plaques.

Keep nails appropriately trimmed and discuss persistent itching with a healthcare professional.

Bathe gently

Use comfortably warm rather than excessively hot water.

Avoid aggressively scrubbing psoriasis plaques.

Pat the skin dry rather than rubbing vigorously, and moisturize afterward.

Identify personal triggers

Keeping a record of:

• infections,
• stressful periods,
• medicines,
• skin injuries,
• alcohol consumption,
• weather changes,
• and psoriasis flares

may help reveal patterns.

Avoid smoking

Not smoking benefits cardiovascular, respiratory and overall health and may also help reduce factors associated with psoriasis severity.

Maintain overall health

Regular physical activity, adequate sleep and a balanced diet support general health.

People with overweight or obesity who are advised to lose weight may find that achieving a healthier weight also improves treatment response or psoriasis severity.

Is There a Special Psoriasis Diet?

There is no single diet proven to cure psoriasis.

Be cautious about websites or products claiming that particular:

• foods,
• supplements,
• detoxes,
• juices,
• herbal preparations,
• or restrictive diets

can eliminate psoriasis.

A balanced eating pattern supporting overall cardiovascular and metabolic health is sensible.

People considering supplements should discuss them with a healthcare professional, particularly if they take prescription medicines.

When Should You See a Healthcare Professional?

Arrange medical assessment if:

• you develop a persistent unexplained rash,
• psoriasis is widespread,
• symptoms interfere with sleep or everyday activities,
• treatments are not controlling the disease,
• psoriasis affects sensitive areas,
• your nails develop significant changes,
• or you develop joint symptoms.

Professional assessment can confirm whether the problem is psoriasis and determine the most appropriate treatment.

When Can Psoriasis Be an Emergency?

Most psoriasis does not require emergency treatment.

However, seek urgent medical care if you develop:

• widespread intense skin inflammation,
• extensive peeling,
• widespread pustules,
• fever or chills with rapidly worsening psoriasis,
• severe weakness,
• rapid heartbeat,
• dehydration,
• or other signs of serious illness.

These symptoms can occur with severe forms such as erythrodermic or generalized pustular psoriasis, which may require hospital treatment.

The Bottom Line

Psoriasis is a chronic immune-mediated inflammatory disease, not an infection and not a result of poor hygiene.

It is not contagious.

The most common form is plaque psoriasis, but other forms include:

• guttate psoriasis,
• inverse psoriasis,
• pustular psoriasis,
• erythrodermic psoriasis,
• scalp psoriasis,
• and nail psoriasis.

Psoriasis cannot currently be cured or reliably prevented, but it can often be effectively controlled.

Treatment may include:

• moisturizers,
• topical medicines,
• phototherapy,
• systemic medicines,
• and biologic therapies.

People with psoriasis should also be aware of symptoms of psoriatic arthritis, because early treatment can help prevent permanent joint damage.

Severe widespread redness, extensive skin peeling, widespread pustules or serious illness requires urgent medical assessment.

Medical Disclaimer

This article provides general health information for an international audience and is not a substitute for diagnosis or treatment by a qualified healthcare professional or dermatologist. Psoriasis can resemble other skin conditions, and treatment varies according to the type, severity, location and individual medical history. Do not stop prescribed medication or begin prescription psoriasis treatment without appropriate medical advice. Seek urgent medical care for widespread severe inflammation, extensive peeling, widespread pustules, fever or other signs of serious illness.

Sources and Further Reading

World Health Organization — Psoriasis Information Sheet

https://www.who.int/docs/default-source/ncds/psoriasis-info-sheet-3.pdf

World Health Organization — Global Report on Psoriasis

https://iris.who.int/handle/10665/204417

National Institute of Arthritis and Musculoskeletal and Skin Diseases — Psoriasis

https://www.niams.nih.gov/health-topics/psoriasis

National Institute of Arthritis and Musculoskeletal and Skin Diseases — Psoriasis Diagnosis and Treatment

https://www.niams.nih.gov/health-topics/psoriasis/diagnosis-treatment-and-steps-to-take

National Institute of Arthritis and Musculoskeletal and Skin Diseases — Psoriatic Arthritis

https://www.niams.nih.gov/health-topics/psoriatic-arthritis

American Academy of Dermatology — Psoriasis Treatment

https://www.aad.org/public/diseases/psoriasis/treatment/treatment