What is Psoriasis?

Psoriasis

What is psoriasis?

Psoriasis is a skin condition that causes scaly red patches on your skin. There's no cure for psoriasis, but there are treatments that can help.

To understand your psoriasis, it helps to know a little about how your skin works.

Psoriasis causes scaly red patches on your skin.

Your skin is made up of several layers of cells. The top layer is called the epidermis. All the time, new skin cells form inside the epidermis. Then they slowly move to the outside of your skin. When the cells reach the surface of your skin, they fall off. This turnover of skin cells usually happens over three to four weeks.

If you have psoriasis, this turnover happens much faster. The new skin cells take only three or four days to reach the surface. So the extra cells on your skin’s surface build up and make flaky patches. Sometimes the extra cells cause bad dandruff on your scalp.

We don't fully understand why psoriasis happens to some people. The

genes
Your genes are the parts of your cells that contain instructions for how your body works. Genes are housed on chromosomes, structures that sit in the nucleus at the middle of each of your cells. You have 23 pairs of chromosomes in your normal cells, each of which has thousands of genes. You get one set of chromosomes, and all of the genes that are on them, from each of your parents.

genes you get from your parents may play a part. About a third of people with psoriasis have a relative with the condition.

Source:
Naldi L, Chatenoud L, Linder D, et al.
Cigarette smoking, body mass index, and stressful life events as risk factors for psoriasis: results from an Italian case-control study.
Journal of Investigative Dermatology. 2005; 125: 61-67.

Some other things may also cause psoriasis. These include:

An injury, such as a scratch on your skin or a scar from an operation
An

infection
You get an infection when viruses, bacteria, fungi or other tiny organisms get into your body. These bugs are so tiny that you can't see them without a microscope. For example, an infection in your airways causes the common cold. And an infection in your skin can cause rashes such as athlete's foot.

infection
Some medications, including lithium salts (used to treat

mania
If you have mania, you feel extremely happy, excited or irritable for no reason. It can be a symptom of some mental illnesses. You may get insomnia, your energy levels may be unusually high and you may behave in inappropriate ways.

mania) and beta-blockers (used for heart conditions).

Some people with psoriasis find that their symptoms come and go. Others have flare-ups, when their symptoms get worse. There’s some evidence that flare-ups of psoriasis may be linked to:

Something stressful happening in your life
Your habits, such as cigarette smoking
Being overweight
Not eating enough fruits and vegetables.

You can get different types of psoriasis.

Source:
U.S. National Library of Medicine.
Psoriasis.
Available at http://www.nlm.nih.gov/medlineplus/print/ency/article/000434.htm (accessed 16 February 2009).

² Here we look only at chronic plaque psoriasis. We don't look at treatments for nail, scalp or other kinds of psoriasis.

It's important to know that psoriasis is:

Not infectious. This means you can't catch psoriasis and you can't pass it on to anyone else
Not caused by poor skin hygiene
Not a form of skin cancer.

Sources for the information on this page:

Naldi L, Chatenoud L, Linder D, et al.Cigarette smoking, body mass index, and stressful life events as risk factors for psoriasis: results from an Italian case-control study.Journal of Investigative Dermatology. 2005; 125: 61-67.

U.S. National Library of Medicine.Psoriasis.Available at http://www.nlm.nih.gov/medlineplus/print/ency/article/000434.htm (accessed 16 February 2009).

This information was last updated on Apr 22, 2009

This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment.
© BMJ Publishing Group Limited 2009. All rights reserved.

The information on ConsumerReportsHealth.org should not be viewed as a substitute for a consultation with a medical or health professional. The information is meant to enhance communication with your doctor, not replace it. Consumers Union can not be liable for any loss, injury, or other damages related to your use of this information.

Your use of this information is subject to our User Agreement available at www.ConsumerReportsHealth.org.