What causes psoriasis?

We don’t know exactly what causes psoriasis, but it appears that a combination of factors contribute to its development. Basically, psoriasis starts with inflammation in the skin that prompts new skin cells to develop. The process starts in the basal (bottom) layer of the epidermis, where keratinocytes are made. Keratinocytes are epidermal skin cells that produce keratin, a tough protein that helps form hair, nails, and skin. In normal cell growth, keratinocytes grow and move from the bottom layer to the skin’s surface and shed unnoticed. This process takes about a month.

In people with psoriasis, the keratinocytes multiply very rapidly and travel from the basal layer to the surface in about three to four days. The skin cannot shed these cells quickly enough, so they build up, leading to thick, dry plaques. Silvery, flaky areas of dead skin build up on the surface of the plaques. The underlying skin layer (dermis), which contains the nerves, blood, and lymphatic vessels, becomes red and swollen.

From The Mind-Beauty Connection: 9 Days to Less Stress, Gorgeous Skin, and a Whole New You by Amy Wechsler.

Dr. Mehmet Oz, MD
Cardiology (Cardiovascular Disease)
Psoriasis is an autoimmune disease that is affected by sunlight.  Dr. Oz answers singer LeAnne Rhimes' question about psoriasis in this video.

Psoriasis is most likely caused by a malfunctioning immune system. In this particular case, the malfunction has to do with white blood cells known as T cells. If you have psoriasis, your T cells aren't operating as they should, causing inflammation and a buildup of extra skin cells. Unfortunately, no one knows what causes this malfunction. But in addition to knowing that the condition has something to do with your immune system, researchers have also linked it to genetics. Several genes responsible for psoriasis have already been identified. Your environment can play a role too, and it's possible that psoriasis may be caused by a combination of all three of these factors.

Continue Learning about Plaque Psoriasis

Tracking Your Psoriasis Triggers
Tracking Your Psoriasis Triggers
Patches of bright, red skin? Check. Scaling? Check. Itching and uncomfortable skin inflammation? Check. If you have psoriasis, you’re already well ac...
Read More
How effective is secukinumab?
Donna Hill Howes, RNDonna Hill Howes, RN
Studies show secukinumab works very well for relieving psoriatic arthritis symptoms and slowing join...
More Answers
Foods That Could Make Your Psoriasis Worse
Foods That Could Make Your Psoriasis WorseFoods That Could Make Your Psoriasis WorseFoods That Could Make Your Psoriasis WorseFoods That Could Make Your Psoriasis Worse
You might want to rethink hitting happy hour.
Start Slideshow
What Can Happen if Psoriasis Goes Untreated?
What Can Happen if Psoriasis Goes Untreated?

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.