What Is Psoriasis?

Causes, Triggers, Symptoms, Types, and Treatment

A person with psoriasis on their arm.

Tanja Ivanova / Getty Images

Psoriasis is an autoimmune skin disease. The underlying cause is a malfunctioning immune system that attacks healthy tissue. This reaction causes inflammation that encourages skin cells to reproduce too quickly. The skin cells then pile up, forming patches of skin called plaques. Psoriasis often comes with flare-ups, times when symptoms intensify, which may be linked to triggers.

There are different types of psoriasis, but the most common is plaque psoriasis. It affects 80% to 90% of people with the condition.  Psoriasis plaques can appear anywhere on the body, but they most commonly appear on the knees, elbows, scalp, and trunk.

Psoriasis sometimes occurs with another autoimmune disease called psoriatic arthritis (PsA), which mainly affects the joints and the areas where ligaments and tendons meet bone.

This article covers the causes of psoriasis, its symptoms, diagnosis, treatment, and more. 

Psoriasis Symptoms

Psoriasis plaques (thick skin areas) can develop on different body parts. The plaques are sometimes covered with scales, a thick white or grayish coating of dead skin cells.

Color: On lighter skin tones, plaques appear red and are covered in silvery scales. On darker skin, they may appear salmon-colored, dark brown, purple, or violet with grayish scales. People with darker skin might also have more scaling, more affected skin areas, and skin lesions misdiagnosed as hyperpigmentation (patches of darker skin).

Lesion size and location: Psoriasis plaques can appear on both small and large areas. Small psoriatic lesions sometimes join to form larger patches. Plaques typically appear in the same areas on both sides of the body. For example, if one knee or elbow is covered, the other is also affected.  

How it feels: Plaques will be itchy, painful, and tender. Scratching can cause abrasions and allow fluids to leak from the skin. This can lead to secondary infections.

Additional symptoms of psoriasis are:

  • Small, scaly, teardrop-shaped spots, which are more common in children
  • Dry, cracked skin that may also bleed
  • Itching or burning 
  • Sore, painful skin around patches 
  • Thick, pitted nails
  • Swollen, painful joints
dry skin on scalp

anand purohit / Getty Images

Types of Psoriasis

Psoriasis types include:

  • Plaque psoriasis: The most common type of psoriasis, this causes thick, red lesions with silvery scales that pile upon the skin.
  • Guttate psoriasis: This type causes small, red scaly spots on the arms, legs, and torso. It typically starts after a bacterial infection. "Guttate" means "colored spots or drops." This type of psoriasis is more common in younger people.
  • Inverse psoriasis: This psoriasis type causes red, inflamed skin areas in body fold areas—the underarms, under the breasts, and around the genitals.
  • Pustular psoriasis: This is a rare type of psoriasis that causes pus-filled bumps on the skin. Bumps often appear on the hands and feet. 
  • Erythrodermic psoriasis: This rare type causes a red rash resembling a burn over most of the body. It might also cause fever, chills, and dehydration. Erythrodermic psoriasis is a medical emergency and should be treated in a hospital.
  • Nail psoriasis: This type causes nails to become damaged, pitted, split, and lifted. It often occurs with plaque psoriasis and psoriatic arthritis.
  • Psoriatic arthritis: PsA affects some people with psoriasis. Symptoms include joint pain, severe swelling of the fingers and toes, inflammation in the areas where ligaments and tendons meet bone, and eye inflammation. 
Guttate psoriasis on a back
guttate psoriasis.

Reproduced with permission from © DermNet New Zealand www.dermnetnz.org 2023.

Left hand thumb with fingernail psoriasis. Psoriasis is an autoimmune disease.
Fingernail psoriasis.

Rupert Weidemann / Getty Images

What Causes Psoriasis?

The cause of psoriasis is an immune system attack on the body's tissues. White blood cells, called T cells, mistakenly attack skin cells, which causes skin cell production to increase. The new skin cells are pushed to the skin’s surface, where they pile up.

Many people inherit genes that make it more likely for them to develop psoriasis. If you have a family member with the condition, you are at increased risk for psoriasis.

The symptoms of psoriasis can develop because of specific disease triggers. These, in combination with genetic predisposition, increase your risk for psoriasis. Factors that may lead to the development of psoriasis include:

Psoriasis Is Not Contagious

Psoriasis is not a contagious condition. It occurs because of a problem with the immune system and is linked to genetics and environmental risk factors. You cannot catch psoriasis from someone else, whether by touching lesions or sharing personal care items.

Psoriasis Flare Triggers

Psoriasis is known for causing periods of flare-ups, when symptoms of the condition worsen. Triggers like stress, diet, smoking, alcohol consumption, skin trauma, illness, medications, and weather changes often cause flare-ups. 

  • Stress: Your immune system creates an inflammatory response to stress, which can lead to psoriasis symptoms. Try to reduce stressors through regular stress management activities, like exercising regularly. 
  • Diet: Research shows diet may play a part in the severity of psoriasis and the number of flares a person experiences. Eating a healthy diet with plenty of anti-inflammatory foods (such as the Mediterranean diet) might help keep psoriasis symptoms at bay.
  • Smoking: Smoking, including secondhand smoke, is a known trigger for psoriasis. Aim to quit smoking and avoid the being in the presence of secondhand smoke.
  • Alcohol consumption: Alcohol can trigger inflammation and worsen symptoms in some people with psoriasis. Alcohol might also reduce the effectiveness of medications and even lead to more severe drug side effects.
  • Skin trauma: An injury to the skin, such as a bug bite, scrape, bruise, or sunburn, can cause your psoriasis to flare up, especially in the skin trauma area. To reduce your risk of an outbreak, attend to skin injuries quickly by treating them, managing itching, and avoiding scratching. 
  • An illness: A psoriasis flare can occur from two to six weeks after an infection, such as strep throat or an ear infection. Reduce your risk of a flare by treating the infection quickly and taking time to rest and get better.
  • Medications: Some medications can trigger a psoriasis flare. If a medication is a trigger, you may have a flare two to three weeks later after starting it. Lithium, antimalarial drugs, beta-blockers, ACE inhibitors (angiotensin converting enzyme inhibitors), and NSAIDs (nonsteroidal anti-inflammatory drugs) such as Advil or Motrin (ibuprofen) are some of the known triggers.
  • Weather changes: Cold, dry weather and spending too much time in air-conditioned rooms can trigger a psoriasis flare.
  • Obesity: Fat tissue releases inflammatory proteins called adipokines, and research shows that weight loss can improve psoriasis symptoms. Weight loss might also improve response to psoriasis treatments. 

Diagnosis of Psoriasis

If you have skin irritation, a rash, or flaky, dry skin that lasts longer than a few weeks, see a healthcare provider. Your provider will examine your skin and determine the cause of skin lesions. For an accurate diagnosis, you will want to see a dermatologist—a specialist in diagnosing and treating nail, skin, and hair conditions. 

To diagnose psoriasis, your healthcare provider will ask questions about your health and examine your skin, nails, and scalp. They might also take a small sample of the affected skin (biopsy) to examine under a microscope. A skin biopsy can distinguish psoriasis from other skin diseases. 

Psoriasis Severity

Psoriasis severity varies from person to person. The condition is measured on a scale from mild to severe. According to the National Psoriasis Foundation:

  • Mild: Psoriasis covers up to 3% of the body (1% of the body is about the size of an adult hand)
  • Moderate: Psoriasis covers 3% to 10% of the body.
  • Severe: Psoriasis covers more than 10% of the body. It typically appears in many body areas, requires systemic (whole-body) treatment, and significantly affects a person’s quality of life.

Psoriasis Treatment 

The goal of psoriasis treatment is to stop skin cells from growing and to remove scales. Your options for treating psoriasis are topical medicines (creams, ointments, etc.), oral and injected medicines, and phototherapy (light therapy).

The treatment your healthcare provider recommends will depend on the severity of your psoriasis symptoms and how responsive you have been to previous treatments. You might need to try different medicines or a combination of treatments before you find something that best works for you. 

Topical medicines: Topical medicines for psoriasis include calcineurin inhibitors, corticosteroids, coal tar, retinoids, salicylic acid, vitamin D creams, and anthralin (a tar cream). Many of these are prescribed alone or in combination with oral or injected medicines. Topical medicines are available over the counter (OTC) or by prescription.

Oral/injected medicines: If you have moderate to severe psoriasis or topical treatments have not helped you, your healthcare provider might prescribe systemic oral and injected medicines. These medicines are systemic because they affect the entire body and work to calm down your overactive immune system.

These include:

Phototherapy: Also called light therapy, phototherapy is prescribed to people with moderate to severe psoriasis alone or with other therapies. It involves exposing the skin to consistent and controlled amounts of light.

Your options for light therapy might include ultraviolet (UV) B broadband, UVB narrowband, psoralen plus ultraviolet A (PUVA), and excimer laser.

Is Psoriasis Curable?

Psoriasis is a lifelong condition that never goes away. There is no cure for it, and you will need to manage the condition for the rest of your life. The goals of psoriasis treatment are to reduce disease severity and improve quality of life. Healthcare providers focus on the goals that matter to the person living with psoriasis.

It typically goes through periods of flare-ups and remission (improved symptoms). The average time for remission is one to 12 months, but some people experience remission for a year or longer.

Even with remission, the underlying disease process is always there, and symptoms can return at any time. That is why staying on top of your treatment plan is crucial. 

Lifestyle and Complementary or Alternative Treatments

Some lifestyle habits might affect the way your treatments work. For example, smoking and drinking alcohol might reduce the effectiveness of some medicines. Changing your lifestyle may help you better manage your psoriasis. Your healthcare provider can help you to decide what alternative treatments might help you.

Complementary and integrative therapies recommended by the National Psoriasis Foundation include:

  • Diet and nutrition: A healthy diet might help you lose excess weight, improve symptoms and reduce inflammation effects on your body. 
  • Physical activity: Exercise can improve your overall health, help you lose weight, and lower your risk for conditions linked to psoriasis, like heart disease and type 2 diabetes.
  • Mind-body therapies: Therapies like yoga, tai chi, and meditation can help reduce stress and help you to manage psoriasis with an open mind.

Let your healthcare provider know if you want to try alternative therapies like acupuncture, herbal therapies, and dietary supplements. They can help you decide which therapies might benefit you and your unique health situation. 

How Long Will Treatments Take to Work?

When you start a new treatment, results will not come quickly. The National Psoriasis Foundation recommends waiting at least three months before deciding whether a treatment works.

The organization considers a 75% improvement or reduced skin involvement to 3% body areas an acceptable treatment response. However, newer therapies can offer 90% to 100% skin clearance.

Psoriasis symptoms do not go away overnight, so patience is key. Don’t stop taking medicines or going to your phototherapy appointments because symptoms have improved. Psoriasis is a chronic condition. It requires long-term care, and you should never stop or change treatments without first checking with your healthcare provider. 

If you have received a diagnosis of psoriasis and are experiencing new or worsening symptoms, you will want to reach out to your healthcare provider. You should also inform them if treatments don’t appear to be helping or if side effects affect your quality of life.

Risks and Complications Associated With Psoriasis 

People living with psoriasis might develop comorbid conditions—diseases that are present simultaneously with psoriasis. 

Some health conditions affect people with psoriasis more commonly than the general population. These include:

  • Heart disease
  • Stroke
  • Type 2 diabetes
  • Inflammatory bowel disease (IBD), such as Crohn's disease and ulcerative colitis
  • Depression

This is because the same inflammatory processes present in psoriasis are also responsible for many of these other serious conditions.

Medications for treating psoriasis suppress the immune system and make you more vulnerable to bacteria, viruses, and pathogens. 

You can reduce your risk for disease complications by following your treatment plan exactly as prescribed. If you get sick, you want to reach out to your healthcare provider, follow their advice, and allow time to rest and get better to keep illnesses from becoming severe.

If you notice new or worsening symptoms, contact your healthcare provider immediately. These could be signs of another condition, worsening psoriasis, or reduced treatment response. Addressing these issues quickly helps you avoid serious problems.

Living With Psoriasis

Living with psoriasis is difficult. You might experience skin pain that causes burning, stinging, cracking, bleeding, and itching. If you have PsA, you might also have joint pain and swelling in your fingers or toes and in the entheses, areas where tissue, such as tendons and ligaments, attaches to bone. There are ways to address these problems, such as:

  • Managing triggers: You can identify what causes your psoriasis outbreaks by tracking when you experience symptoms and what leads to them. Your healthcare provider can also evaluate your treatment plan to help you reduce triggers.
  • Keeping skin moisturized: Using a moisturizing cream can help you avoid dry skin, itching, and swelling. It also helps to heal your skin.
  • Softening scales: You can use products containing salicylic acid or glycolic acid to soften scales. These ingredients help break up dead skin cells that build up on plaques.
  • Capsaicin for joint pain: Capsaicin is a substance in chili peppers, and it can help relieve joint swelling. You should check with your healthcare provider to see if it is safe to use on psoriatic skin.
  • Treating itch: Many OTC options are available to manage the itch from psoriasis, including hydrocortisone and lotions containing menthol or pramoxine. Ask your healthcare provider what they recommend for itchy skin.
  • Cold packs: Cold can help to manage joint swelling and itching. For itching, cold confuses the brain because it cannot feel cold and itchy at the same time. For joint pain, cold can bring down swelling.
  • Washing the scalp with vinegar: According to the National Psoriasis Foundation, a diluted formula of apple cider vinegar can help to calm an itchy scalp. You will want to avoid using vinegar if there is bleeding or cracking.

Psoriasis Statistics and Stigma

Psoriasis affects around 7.5 million American adults. Because its effects are visible, many people have misconceptions about the disease, including that if can be passed on to others by touch. A worldwide survey found that 84% of those with psoriasis had experienced humiliation or negative social consequences due to their condition.

Some people are concerned that psoriasis isn’t treatable or that clear skin is impossible. But there are plenty of effective treatments. You can experience clear or nearly clear skin by working with your healthcare provider and following your treatment plan.

Psoriasis is not "just a rash." For most people with psoriasis, the condition causes problems in their everyday lives and can increase their risk for serious health problems, including depression and anxiety.

Some people believe that psoriasis results from bad hygiene. But hygiene habits, good or bad, are not the cause of psoriasis. It is also not contagious. It can't be spread to others by contact or sharing personal items.

Summary

Psoriasis occurs because the immune system malfunctions and causes skin cells to grow too quickly, so they pile up. It is characterized by periods of flare-ups and remission. Specific stressors, including mental stress, skin trauma, illness, and lifestyle habits, trigger flare-ups.

Plaque psoriasis is the most common type. It causes thick, red lesions. Psoriasis is diagnosed with a medical history, physical exam, and a biopsy. Psoriasis has no cure. Treatment is aimed at remission or nearly clear skin. Treatment options include topical therapies, oral and injected medicines, and light therapy.

23 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Psoriasis Foundation. Plaque psoriasis

  2. National Psoriasis Foundation. Skin of color resource center.

  3. Yang J, Lee K, Chang GT. Treatment of psoriasis with exudation: three case studies. Journal of Korean Medicine. 2016;37(2):110-118. doi:10.13048/jkm.16027

  4. American Academy of Dermatology Association. Can a child have psoriasis?

  5. American Academy of Dermatology Association. Types of psoriasis: can you have more than one?

  6. American Academy of Dermatology Association. Psoriasis: causes.

  7. Huang YH, Kuo CF, Huang LH, Hsieh MY. Familial aggregation of psoriasis and co-aggregation of autoimmune diseases in affected familiesJ Clin Med. 2019;8(1):115. doi:10.3390/jcm8010115

  8. Kamiya K, Kishimoto M, Sugai J, et al. Risk factors for the development of psoriasisInt J Mol Sci. 2019;20(18):4347. doi:10.3390/ijms20184347

  9. Tampa M, Sarbu MI, Mitran MI, et al. The pathophysiological mechanisms and the quest for biomarkers in psoriasis, a stress-related skin diseaseDis Markers. 2018;2018:5823684. doi:10.1155/2018/5823684

  10. Ford AR, Siegel M, Bagel J, et al. Dietary recommendations for adults with psoriasis or psoriatic arthritis from the Medical Board of the National Psoriasis Foundation: a systematic reviewJAMA Dermatol. 2018;154(8):934-950. doi:10.1001/jamadermatol.2018.1412

  11. American Academy of Dermatology Association. Are triggers causing your psoriasis flare-ups?

  12. Liu S, He M, Jiang J, et al. Triggers for the onset and recurrence of psoriasis: a review and update. Cell Commun Signal. 2024;22(1):108. doi:10.1186/s12964-023-01381-0

  13. National Psoriasis Foundation. Why treat?

  14. National Psoriasis Foundation. Treatment & care.

  15. Svoboda SA, Ghamrawi RI, Owusu DA, Feldman SR. Treatment goals in psoriasis: which outcomes matter most? Am J Clin Dermatol. 2020;21(4):505-511. doi:10.1007/s40257-020-00521-3

  16. American Academy of Dermatology Association. How long will I have to treat my psoriasis?

  17. National Psoriasis Foundation. Complementary and integrative medicine.

  18. National Psoriasis Foundation. Treat to target.

  19. Subramonian A, Walter M. Newer biologics for the treatment of plaque psoriasis [Internet]. Ottawa (ON): Canadian Agency for Drugs and Technologies in Health; 2021.

  20. Lowes MA, Suárez-Fariñas M, Krueger JG. Immunology of psoriasisAnnu Rev Immunol. 2014;32:227-255. doi:10.1146/annurev-immunol-032713-120225

  21. National Psoriasis Foundation. Integrative approaches to care.

  22. Armstrong AW, Mehta MD, Schupp CW, et al. Psoriasis prevalence in adults in the United StatesJAMA Dermatol. 2021;157(8):940-946. doi:10.1001/jamadermatol.2021.2007

  23. Armstrong A, Jarvis S, Boehncke WH, et al. Patient perceptions of clear/almost clear skin in moderate-to-severe plaque psoriasis: results of the Clear About Psoriasis worldwide survey. J Eur Acad Dermatol Venereol. 2018;32(12):2200-2207. doi:10.1111/jdv.15065

By Lana Barhum
Lana Barhum has been a freelance medical writer since 2009. She shares advice on living well with chronic disease.