Psoriasis Frequently Asked Questions

What causes psoriasis?

As a dermatologist, I talk to a lot of patients about their skin disease. Although much of our conversation centers around patient-specific treatment plans, there are also some questions that most patients tend to ask, especially when they are newly diagnosed. Of course, if you have questions about your personal health it's always a good idea to see a board certified dermatologist. The National Psoriasis Foundation is also a great source of information.

What causes psoriasis?

Although we don’t know exactly what causes psoriasis (or even if all types of psoriasis are really the same disease), scientists suspect it is a combination of inherited and environmental factors that trigger the immune system to go haywire and attack the skin. This perpetual attack causes the skin to thicken and flake, leading to the typical pink, scaly plaques seen in psoriasis.

We know that certain factors can trigger or worsen psoriasis, for example psoriasis is often triggered by an infection (such as a strep throat).

Medications can worsen psoriasis, especially beta-blockers for blood pressure (like atenolol or metoprolol), lithium, or prednisone. (Note that you should never stop taking one of these medications without consulting the doctor who prescribed it first.)

Stress is a common trigger of psoriasis as well, which can be physical stress like surgery or childbirth, or emotional stress like a death in the family, divorce, or financial troubles.

Who gets psoriasis? (And why did I get it?)

Psoriasis is very common - about 3% of the American population has it. It can begin at any age, but once someone has psoriasis, it is a chronic disease and persists for life. Infants only rarely have it, but it can develop in childhood, especially in pre-teens and teenagers. For adults, there are two peaks of incidence at about age 20 and age 50.

Psoriasis also affects people of all races and both genders.

Since psoriasis is very common, there are many celebrities with psoriasis and psoriatic arthritis and most people know someone who has it as well.

What does psoriasis look like?

Psoriasis has many different forms, the most common being chronic plaque psoriasis which causes thick, pink plaques with thick and flaky scale. These can occur anywhere on the body, but are most common on the scalp, behind the ears, elbows, knees, umbilicus (belly button), and the lower back. The extent of disease can range widely from only a few small spots to most of the body covered.

Other forms of psoriasis may only affect specific areas, such as the scalp, fingernails, hands, or genitals. Psoriasis can also present with different appearances, including small white pustules (pustular psoriasis), very small and numerous “raindrop” spots (guttate psoriasis - often in younger patients or after an infection), or thick scale on only the palms and soles (palmoplantar psoriasis).

What does psoriasis feel like?

Psoriasis can have a wide variety of symptoms, ranging from mild to severe. Some people have no symptoms from their psoriasis and can only tell it is there by looking at it.

Itching is a very common and annoying symptom of psoriasis, as is flaking. Flakes from the scalp can accumulate on the shoulders making it hard to wear dark clothing. Scratching or the rubbing of clothing can lead to small piles of flakes on a chair or the floor.

Pain is also a common symptom of psoriasis. The skin can be painful at the sites of the plaques, especially if they crack the skin open (sometimes call a fissure). These cracks can then be made more painful when exposed to alcohol, certain chemicals, or spicy foods. Cracks on the hands can be especially difficult and make it difficult to work in certain jobs, while cracks on the feet can make walking painful or even impossible if severe.

About 30% of people with psoriasis will also have psoriatic arthritis which is pain in the joints, most commonly presenting as stiffness in the morning or after sitting for long periods. Although any joint can be affected, most commonly the lower back or small joints of the hand and feet are painful or stiff.

As with skin psoriasis, psoriatic arthritis can range widely in severity. Mild psoriatic arthritis may just be an annoyance, but in its more severe forms it can cause significant pain and permanent destruction of the joints if not treated.

Some patients do not recognize that they have psoriatic arthritis as they attribute their joints pains to “getting older” or more common forms of arthritis (like osteoarthritis).

How does a doctor diagnosis psoriasis?

An experienced doctor (generally a board certified dermatologist) can generally recognize psoriasis from a thorough examination of the skin. Occasionally, a skin biopsy is used to confirm the diagnosis, although it is not necessary in most situations. A skin biopsy involves a small injection of a numbing agent (like lidocaine) and the removal of a small (~1/5th of an inch) piece of skin for microscopic examination by a laboratory.

Currently there are no blood tests that can convincingly diagnosis psoriasis or psoriatic arthritis, although there is substantial research in this area. X-rays are sometimes helpful in diagnosing and monitoring psoriatic arthritis. A rheumatologist (joint specialist) typically monitors and treats psoriatic arthritis.

Is psoriasis just a skin disease?

No. Although the inflammation from psoriasis is most visible on the skin, recent studies have shown that inflammation is present throughout the major organs of the body in people with psoriasis, even if they feel well. Not only can psoriasis lead to potentially permanent joint problems, but people with psoriasis are also at substantially increased risk of diabetes, heart disease, stroke, and depression.

It is not yet clear how the severity of someone’s psoriasis affects these risks. There is some evidence that treating the psoriasis (especially with some of the newer medications) can lower these risks, although the data is early and the most rigorous types of studies have not been completed to answer this important question.

Because of these associations with serious conditions, people with psoriasis are at 50% risk for early death compared to people who do not have it, and patients with severe psoriasis die an average of 4 years earlier. For that reason, it is important for people with psoriasis to get help managing their disease, while also taking good care of their general health.

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