Psoriasis: what is it, causes, symptoms, treatment

Felix Gussone, MD - Contributor Avatar

Reviewed by Felix Gussone, MD, Ro, 

Written by Kristin DeJohn 

Felix Gussone, MD - Contributor Avatar

Reviewed by Felix Gussone, MD, Ro, 

Written by Kristin DeJohn 

last updated: Sep 30, 2021

6 min read

If you have psoriasis, you’re far from alone: more than 7.5 million adults in the United States have this skin condition (Armstrong, 2021). 

Not only can it take a toll on you physically, but it can be difficult emotionally as well. While it’s not contagious, you may feel self-conscious or even avoid social contact with other people altogether.  To better understand how you can live more comfortably with psoriasis, it’s important to first understand what it is, what causes it, and how to properly and safely manage it. 

Healthier skin

Custom Rx treatment for your skin type and skin goals

What is psoriasis?

Psoriasis is a non-contagious, chronic, inflammatory skin disease that causes scaly, red patches or “plaques.” The plaques are the result of a build-up of skin. The body usually replaces skin cells every 30 days. With psoriasis, inflammation speeds this cycle up to about every week. The skin cell growth leads to raised, red patches. At the same time, the top layer of skin doesn’t secrete the normal oils seen in healthy skin, leading to flaky, dry silvery scales (Rajguru, 2020; Nair, 2021).

Psoriasis flare-ups often occur on the elbows, knees, around the waist, back, and scalp. It may appear in a few spots or cover large parts of the body. It can also affect other areas including the nails, face, mouth, eyes, genitals, and joints. For some, it clears up and goes away, then comes back. For others, it’s a continual problem (Rajguru, 2020; Kim, 2017).

What causes psoriasis? 

Psoriasis affects all ages, often striking those who are 15 to 20 years old and 55 to 60. It is an immune-mediated disease because the body’s own immune system is activated when it shouldn’t be. The combination of a misfiring immune system and a defective inflammatory response leads to psoriasis (Gran, 2020). 

The immune system ramps up when the body triggers white blood cells called T-cells to attack the skin and produce chemicals that cause inflammation. Blood vessels widen, more white blood cells accumulate, and skin cells multiply. That kicks off an autoinflammatory loop that can keep the flare-up going. What starts the process in the first place? Research shows the causes of psoriasis are usually a combination of genetics, health risk factors, and environmental triggers (Gran, 2020). As of now, it does not have a cure (Nair, 2021; Fry, 2014).

Let’s dive a little deeper into the causes of psoriasis.

Genetics and psoriasis

If you have a brother, sister, parent, or cousin who has psoriasis, you are more likely to develop it. One study shows that, unlike fraternal twins, identical twins have three times the risk of developing psoriasis (Rendon, 2019).

Researchers believe a variety of genetic, environmental, and health conditions boost risk (Rendon, 2019).

Psoriasis triggers and risk factors

In someone with a genetic predisposition, a trigger may be enough to cause psoriasis. The following are known triggers (Kamiya, 2019):  

  • Trauma to the skin (cuts, chemicals, radiation)

  • Infection (Strep throat, Staph infections )

  • Psychological stress

  • Smoking

  • Alcohol

  • Medications (chloroquine, lithium, beta-blockers, steroids, and NSAIDs can worsen psoriasis) (Nair, 2021)

  • Stopping medications (corticosteroids) (NIH, 2020

  • Cold weather (dry air, less sunlight) (Nair, 2021)

There are medical conditions that also increase the risk for psoriasis. Obesity, diabetes, high blood pressure, problems with calcium in the blood (hypocalcemia), and unhealthy cholesterol levels (dyslipidemia) are among the conditions that are known to boost risk (Kamiya, 2019).

Types and symptoms of psoriasis 

Different types of psoriasis often have different patterns and triggers. The following are the most common types of psoriasis skin lesions (Sarac, 2016): 

  • Plaque psoriasis: marked by red, itchy plaques with silver scales that can cover large areas of the skin; the most common form of psoriasis; up to 90% of psoriasis is plaque psoriasis (Kim, 2017) 

  • Guttate psoriasis: small red plaques usually around the torso and limbs; often affects children or teens. Common triggers: respiratory and tonsil infections, strep throat, injuries, beta-blockers, and antimalarial drugs (Saleh, 2021)

  • Inverse psoriasis: appears as bright red shiny areas in the skin folds, such as the groin, armpits, and under the breasts (Micali, 2019)

  • Pustular psoriasis: red, scaly skin with tiny pustules and can cause symptoms like fever; pustular psoriasis can affect the whole body or just the hands and soles of the feet (Rendon, 2019). 

  • Erythrodermic psoriasis: an acute condition that can cover over 90% of the body in inflamed, red skin that sheds in sheets; linked to the withdrawal of systemic steroids. Treatment is needed immediately as it can lead to severe illness, including cardiac failure (Nair, 2021; Liao, 2016). 

Psoriasis also affects different parts of the body and can result in:  

  • Psoriatic arthritis: This type of inflammatory arthritis affects up to 30% of people with psoriasis. It usually involves painful joints and often affects the joints of the fingers and toes. It can also affect the hips, knees, and spine, causing lower back pain (Sarac, 2016). 

  • Nail psoriasis: presents as pitting or oil spots on the fingernails and toenails; causes discoloration and crumbling nails that detach from the nail bed (Bardazzi, 2019). 

  • Scalp psoriasis: Sebopsoriasis presents as red plaques with greasy scales. It can also affect the forehead and folds around the nose (Nair, 2021).

  • Psoriatic eye: can affect both the eyelids and eyes, including the cornea; it can lead to conjunctivitis, corneal dryness, and vision loss (Rajguru, 2020).

  • Genital psoriasis: 63% of adults with psoriasis experience lesions on their genitals. Genital psoriasis comes with itchy, bright red lesions that typically lack the scaling that accompanies psoriatic lesions on other areas of the body (Yang, 2018).  

Long-term health risks of psoriasis

 Psoriasis can boost the risk for the following conditions (Korman, 2020):

Aside from widespread inflammation, psoriasis takes a toll psychologically. Studies link it to an increased risk of depression, anxiety, and even suicidal thoughts in extreme cases. Healthcare providers must make sure to address both physical and emotional aspects of psoriasis. Fortunately, psoriasis treatment does lead to less anxiety and improves quality of life (Rendon, 2019). 

How is psoriasis diagnosed?

Diagnosis starts with a skin, scalp, and nail exam. That can be enough to diagnose psoriasis. If there’s a question, your healthcare provider may take a biopsy to determine the type of psoriasis or rule out other conditions like eczema. A discussion about family history and other conditions such as joint pain is also an important part of the consult (Kim, 2017). 

Based on these findings, seeing a dermatologist is the next step. If your dermatologist suspects or diagnoses psoriatic arthritis, a rheumatologist is a good addition to your healthcare team (Kim, 2017). 

How do you treat psoriasis?

In recent years, several targeted therapies have come onto the market that are effective at clearing the skin of psoriasis and preventing joint damage from psoriatic arthritis. These new medications can suppress the immune system, but they have other side effects. Healthcare providers use them when milder topical treatments or other systemic treatment options don’t work (Rendon, 2019). 

The following topical treatments are common to manage mild-to-moderate psoriasis (Torsekar, 2017):

  • Topical corticosteroids: can reduce inflammation, itching, and redness; various products are available both over-the-counter and by prescription

  • Anthralin: reduces skin cell growth, prevents T-cell activation; used on the body and scalp

  • Coal Tar: used in shampoos and creams to reduce inflammation, scaling, and itching 

  • Salicylic acid: helps slough off dead skin cells, reduces scaling, itching, and inflammation

  • Topical Vitamin D: Cream versions are synthetic forms of Vitamin D and can help slow skin cell growth; they are often used with corticosteroid creams.

  • Topical retinoid (Tazarotene): a form of Vitamin A used to slow skin cell growth; medical professionals advise pregnant women to avoid retinoids due to the potential for congenital disabilities; often combined with topical corticosteroids.

For moderate to severe psoriasis, more aggressive, systemic treatments come into play. A healthcare provider may combine them with topicals. Commonly used systemic treatments include (Nair, 2021):

  • Methotrexate: This has been a standard of care for moderate to severe psoriasis for years. It decreases skin cell growth and inflammation. It can lead to liver damage, so healthcare providers monitor the effects closely. Anyone taking methotrexate should avoid alcohol. 

  • Cyclosporine: reduces inflammation and has a similar result as methotrexate. It does increase the risk of infection, kidney problems, cancer, and high blood pressure. 

  • Biologics:   Biologics are manufactured proteins that interrupt the immune process. They are effective but do increase the risk of certain infections, such as tuberculosis. 

  • Hydroxyurea: This medication can be an option when you can’t use others. Side effects include fever, chills, lower back or side pain, and hoarseness (Lee, 2014). 

Phototherapy (light therapy), consisting of UVA or UVB light, can improve psoriasis. Since these rays can cause skin cancer, sessions are limited. Healthcare providers often add a drug called psoralen (PUVA therapy) to increase light sensitivity and treatment efficacy.  

Medical professionals tailor psoriasis treatment for each person and may combine some therapies for best results. As with all medications, check with your healthcare provider about the side effects.

Lifestyle approaches for psoriasis

Research shows that psychological stress can trigger psoriasis and prolong the length of flare-ups. Working with a healthcare team on the medical management of psoriasis is essential. The following lifestyle approaches can also help (Sarkar, 2016):

  1. Knowing your triggers and avoiding them

  2. Staying hydrated 

  3. Keeping skin moisturized  

  4. Avoiding alcohol and smoking 

  5. Maintaining a healthy weight

  6. Eating a healthy diet 

  7. Exercising regularly

  8. Reducing stress

  9. Taking warm baths with oil or tar solution (a soft brush can help smooth skin)  

  10. Seeking support (counseling or group support)

Creating a support system of friends, family, counselors, healthcare providers, and talking to others about psoriasis reduces depression and improves quality of life (Sarkar, 2016). The National Psoriasis Foundation is a good resource for support groups and education. 

If you or a loved one are experiencing depression, help is out there. You don’t have to suffer in silence.

Suicide Prevention Lifeline

Anxiety and Depression Association of America: List of Support Groups by Region

When to see a doctor

Treating psoriasis early can keep the rashes from getting worse and infected. Early diagnosis also helps prevent other health problems, such as joint damage or heart disease, and can minimize the emotional aspects that can come with flare-ups (Griffiths, 2021). If you think you have psoriasis, even if it’s not bothering you, it’s best to see a healthcare provider. 


If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

How we reviewed this article

Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

Current version

September 30, 2021

Written by

Kristin DeJohn

Fact checked by

Felix Gussone, MD

About the medical reviewer

Felix Gussone is a physician, health journalist and a Manager, Medical Content & Education at Ro.