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What causes Plaque Psoriasis?

Medically reviewed by Melisa Puckey, BPharm. Last updated on Oct 6, 2021.

Official answer

by Drugs.com
  • Plaque psoriasis often starts with something that triggers or sets off plaque psoriasis.
  • The trigger causes problems within the immune system which sends messages to the skin cells.
  • These messages cause the skin cells to be made at a faster rate and the skin cells do not develop properly.
  • The result of this is patches of thickened layer of scaly, silvery, dead skin cells which you see as plaque psoriasis.

The way the immune system sends messages to the skin is by releasing small proteins (cytokines) that causes changes to the skin cells. Some of these small proteins that cause plaque psoriasis are called interleukin-12, interleukin-17, interleukin-22, interleukin-23, Tumor necrosis factor (TNF)-α.

Some medications that treat plaque psoriasis act to block these small proteins.This means instead of the message getting through to cause plaque psoriasis, the message is blocked and the symptoms of plaque psoriasis improves.

These medications are called called interleukin inhibitors and include interleukin-23 antagonist, interleukin-17A antagonist, interleukin-12 and interleukin-23 antagonist and another inhibitor is tumor necrosis factor (TNF) blocker.

What sets off plaque psoriasis to start with?

The first time you get plaque psoriasis, or for those people who have returning plaque psoriasis, the episode may be triggered by a factor or a combination of factors that start off the immune system reaction. These factors include:

  • some medications including hydroxychloroquine, beta blockers, lithium, interferons, imiquimod and terbinafine
  • skin trauma such as injury, infection, a surgical wound, scratch mark or sunburn.
  • rapid withdrawal of oral or systemic corticosteroids
  • infections including bacterial infections eg Streptococcus pyogenes (strep throat) Staphylococcus aureus and yeast infections eg Malassezia, and Candida albicans
  • stress
  • smoking.

What are the risk factors for Plaque Psoriasis?

Anyone can get plaque psoriasis, but there factors that can put you at increased risk:

  • Family history if one parent has plaque psoriasis this increases your risk of getting it. If both parents have it this increases your chances even more.
  • High stress can affect your immune system and as plaque psoriasis is caused by problems in the immune system, high stress can increase your risk of developing plaque psoriasis
  • Smoking can increase your risk of developing plaque psoriasis and also can increase how severe your plaque psoriasis can become.

What does plaque psoriasis look like?

The areas or patches of plaque psoriasis can be:

  • small or large
  • red
  • scaly, which is a silvery white color
  • thickened and raised
  • have well defined edges
  • are commonly on scalp, elbows, knees and lower back but can occur anywhere on the skin
  • may have cracks and skin may split.

Summary

Plaque psoriasis is caused by:

  • A trigger factor that sets off the immune system
  • There is a problem within the immune system.
  • Immune system sends messages to skin cells.
  • Messages cause skin cells to be made at a faster rate and the cells do not develop properly.
  • This results in the thickened layer of scaly, silvery dead skin cells which you see as plaque psoriasis.
References

Advances in Understanding the Immunological Pathways in Psoriasis [Accessed 7/10/2021] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6387410/

Advances in Understanding the Immunological Pathways in Psoriasis [Accessed 7/10/2021] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6387410/
Drug-induced psoriasis: clinical perspectives: [Accessed 7/10/2021] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5774610/
Triggering psoriasis: the role of infections and medications: [Accessed 7/10/2021] https://pubmed.ncbi.nlm.nih.gov/18021899/
Chronic plaque psoriasis: [Accessed 7/10/2021] https://dermnetnz.org/topics/chronic-plaque-psoriasis

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