Causes and Risks Factors of Plaque Psoriasis

A Complex Interaction Between Genetics and Your Environment

As an autoimmune disorder, plaque psoriasis remains something of a mystery in how it causes disease. While genetics play a significant role, other factors are believed to contribute. What is known is that certain conditions and behaviors can either trigger psoriasis symptoms or increase the frequency or severity of an outbreak. These triggers range from infections and obesity to medications and stress.

plaque psoriasis risk factors
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Family history is the strongest risk factor for developing plaque psoriasis. In fact, around a third of the people living psoriasis will report having another family member with the disease. The risk of psoriasis seems all the more likely if both parents are affected.

While scientists have yet to establish how the genetics work, they have identified nine points on a gene associated with psoriasis symptoms, which they have labeled PSORS1 through PSORS9. Of these, people with plaque psoriasis will most often have a chromosomal mutation of PSORS1.

It is hoped that by breaking the genetic code for psoriasis, scientists may one day be able to "switch off" or repair the mutations associated with the disease.

Common Triggers

While plaque psoriasis can affect anyone, there are a number of factors that appear to increase the likelihood of a symptomatic episode, known as a flare.


Both acute and chronic infections can trigger psoriasis symptoms. This is especially seen with HIV, a chronic disease associated with persistent inflammation. While the rate of psoriasis in those with this infection is more or less the same as that of the general population, the severity of the disease is far worse when HIV is involved.

Immune suppression appears to be a defining factor for the activation of psoriasis, whether it is caused a chronic issue like HIV or diabetes or an acute one like bronchitis, strep throat, or the flu.

In contrast, treating an infection can often alleviate symptoms. By way of example, a 2013 study from Poland reported that statin drugs reduced the severity of psoriasis in people with chronic heart disease by helping alleviate the underlying inflammation. The same appears to be true when antiretroviral drugs are used to treat HIV.

Strep infections are one of most common causes of acute onset psoriasis.

Skin Trauma

Skin trauma can also cause plaque psoriasis symptoms, commonly referred to as the Koebner phenomenon. (This response is also seen with other skin conditions such as warts, lichen planus, and molluscum contagiosum.) As many as one in four people with psoriasis experience this phenomenon, triggered by everything from sunburns and insect bites to skin allergies and needle pricks.

Even older skin injuries, such as a surgical wound or tattoo, can suddenly and unexpectedly become the primary site of a psoriasis flare.


Certain medications are known to trigger psoriasis symptoms. They may not affect all people with psoriasis in the same way or cause any symptoms at all. The drugs most commonly cited include:

In addition, the sudden termination of topical corticosteroids used to treat psoriasis can have a "rebound" effect and lead to a severe flare. For this reason, corticosteroids should always be tapered off gradually under the guidance of a doctor if the drug is no longer needed.

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Insofar as lifestyle risks are concerned, there are three that are inextricably linked to the plaque psoriasis: smoking, stress, and obesity.


A 2014 study from the University of California, Davis reported that people who smoke more than a pack of cigarettes per day are twice as likely to have severe psoriasis than those who smoke 10 or fewer cigarettes daily.

Scientists are not sure why this is but believe that smoking may increase the number of autoantigens in the outermost layer of skin known as the epidermis. These are the proteins on the surface of cells that the immune system recognizes as harmful and attacks. Others have suggested that smoking simply triggers or accelerates the autoimmune response.

The researchers also concluded that women who smoke are at greater risk of severe psoriasis than men. The number of years a person has smoked also contributes.


Stress has a cause-and-effect relationship with psoriasis. On one hand, stress can trigger symptoms of the disease; on the other, symptoms can trigger stress. In the same way that the body sends out inflammatory signals to help heal a wound, psychological stress can trigger an inflammatory response that worsens rather than improves your condition.

This is especially worrisome since chronic psoriasis is associated with high rates of depression and anxiety. In some cases, the vicious cycle can only be broken with the appropriate medical treatment, including psychotherapy and the use of antidepressants or anxiolytic (anti-anxiety) drugs.


Obesity can often give rise to the formation of plaques within folds of skin. While the exact cause of this is unclear, a 2012 study in Nutrition & Diabetes suggests that the excessive accumulation of fat increases the production of inflammatory proteins known as cytokines.

Cytokines not only increase inflammation, making symptoms worse, but also promote the formation of plaques in areas where fat volumes are greatest (namely, the skin folds). The association is further evidenced by the relationship between obesity, diabetes, and psoriasis.

Obesity can quadruple a person's risk of type 2 diabetes, and diabetes can increase the risk and severity of plaque psoriasis by 27%.

Frequently Asked Questions

  • What causes plaque psoriasis?

    Plaque psoriasis is an autoimmune disease that causes skin lesions known as plaques. Exactly what causes plaque psoriasis is unclear, but its symptoms are due to abnormal immune system activity that causes skin cells to grow too quickly.

  • What are the risk factors for plaque psoriasis?

    The primary risk factor for plaque psoriasis is a family history of psoriasis. Certain genes predispose a person to develop psoriasis. What’s more, one in three people with psoriasis also has a family member with the autoimmune disease. 

    Other risk factors for plaque psoriasis include: 

    • Infections
    • Medications
    • Obesity
    • Skin trauma
    • Smoking 
  • What triggers plaque psoriasis?

    Plaque psoriasis can be triggered by acute and chronic infections, such as influenza or HIV. Certain medications can also trigger plaque psoriasis. These include lithium, beta-blockers, NSAIDs, anti-malaria drugs, calcium channel blockers, and cholesterol medications.

  • What causes plaque psoriasis to flare up?

    Psoriasis plaques often start as a cut, scratch, bug bite, or other trauma to the skin. The immune system over-responds to the injury, resulting in a build-up of tissue that turns into a plaque. This is known as the Koebner phenomenon. Plaque psoriasis flare-ups can also be brought on by stress, inflammation from other chronic conditions, and lifestyle factors such as smoking. 

9 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. Khalili M, Wong RJ. Underserved Does Not Mean Undeserved: Unfurling the HCV Care in the Safety Net. Dig Dis Sci. 2018;63(12):3250-3252. doi:10.1007/s13671-012-0034-6

  2. Capon F. The Genetic Basis of Psoriasis. Int J Mol Sci. 2017;18(12) doi:10.3390/ijms18122526

  3. Ceccarelli M, Venanzi rullo E, Vaccaro M, et al. HIV-associated psoriasis: Epidemiology, pathogenesis, and management. Dermatol Ther. 2019;32(2):e12806. doi:10.1111/dth.12806

  4. Mosiewicz J, Pietrzak A, Chodorowska G, et al. Rational for statin use in psoriatic patients. Arch Dermatol Res. 2013;305(6):467-72. doi:10.1007/s00403-013-1374-1

  5. Arias-Santiago S, Espiñeira-Carmona MJ, Aneiros-Fernández J. The Koebner phenomenon: psoriasis in tattoos. CMAJ. 2013;185(7):585. doi:10.1503/cmaj.111299

  6. Topical steroids. Prescription topical steroid treatments | National Psoriasis Foundation. June 26, 2019.

  7. Armstrong AW, Harskamp CT, Dhillon JS, Armstrong EJ. Psoriasis and smoking: a systematic review and meta-analysis. Br J Dermatol. 2014;170(2):304-14. doi:10.1111/bjd.12670

  8. Rousset L, Halioua B. Stress and psoriasis. Int J Dermatol. 2018;57(10):1165-1172. doi:10.1111/ijd.14032

  9. Armstrong AW, Harskamp CT, Armstrong EJ. The association between psoriasis and obesity: a systematic review and meta-analysis of observational studies. Nutr Diabetes. 2012;2:e54. doi:10.1038/nutd.2012.26

Additional Reading

By Colleen Doherty, MD
 Colleen Doherty, MD, is a board-certified internist living with multiple sclerosis.