When Jackie was 15, patches of skin near her elbows turned thick and red and began to itch. Sometimes it would get a little better. Other times it got worse. But it never seemed to go away.

Jackie's doctor told her she had a condition known as psoriasis. He recommended a prescription cream and suggested Jackie get outside for 20 minutes in the early mornings before the sun got too strong.

What Is Psoriasis?

Psoriasis (pronounced: suh-rye-uh-sus) is a disease that causes skin cells to build up on the surface of the skin. There they form itchy, red patches (called plaques) and thick scales. Psoriasis can appear anywhere on the body, but is usually found on the scalp, knees, elbows, and torso.

Psoriasis can get better then worse again. It may seem to disappear and then come back. Once someone has it, though, the tendency to get outbreaks isn't likely to go away permanently. For many people, psoriasis isn't a big deal. For others, it can be quite serious.

Right now, there's no cure for psoriasis, but there are good ways to treat it. Eating healthy foods, using moisturizers, and keeping weight in a normal range seem to help for some people. If psoriasis gets bad, though, most people need to see a doctor.

What Causes Psoriasis?

Doctors aren't sure why people get psoriasis, but they do know how the disease works. We all have a kind of white blood cell, called a T lymphocyte (or T cell), in our blood. These cells are part of the immune system. They travel through the bloodstream fighting off bacteria, viruses, and other things that make us sick. Psoriasis causes a person's T cells to mistakenly attack healthy skin as if they were trying to fight an infection or heal a wound.

When psoriasis triggers T cells to attack healthy skin, the body's immune system reacts as it would to a wound or infection — it sends more blood to the area to make skin cells and white blood cells.

Our skin cells are made deep in the skin. Normally, they take about a month to rise to the surface. Once they get there, they die and are sloughed off. With psoriasis, this process is sped up. Skin cells rise to the surface in a few days instead of a month.

The dead skin and white blood cells can't be shed quickly enough. They build up on the surface of the skin as thick red patches. As the skin cells die, they form silvery scales that eventually flake off.

You can't catch psoriasis from another person. You may inherit the genes that make you more likely to get it, though. About 40% of people with psoriasis have a family member who has the disease.

Some of the things that can increase the chances of a psoriasis outbreak are:

• Infections. Strep throat, colds, and other infectious diseases trigger the body's immune system to respond, making a psoriasis outbreak more likely.
• Obesity. The plaques that are produced by many kinds of psoriasis often develop in folds of skin.
• Stress. High stress levels can affect the body's immune system and make psoriasis symptoms worse.
• Certain medicines. Lithium, beta-blockers for high blood pressure, and drugs used to prevent malaria have been shown to increase the risk of psoriasis.
• Skin irritations. Cuts, scratches, sunburns, rashes, and other irritations that affect the skin can make a psoriasis outbreak more likely.
• Cold weather. In the winter, people generally spend more time indoors and get less sun. A moderate amount of direct sunlight can help to improve psoriasis.

What Are the Signs Someone Has It?

People with psoriasis will probably notice one or more of these things:

• raised red patches of skin that can have silvery scales on them
• dry, cracked skin that may bleed at times
• itching, soreness, or a burning feeling in the affected area
• thick fingernails that have indents or "pits"

There are different types of psoriasis:

• Plaque psoriasis is the most common type of psoriasis. Plaque psoriasis causes the skin to be covered with dry red patches (plaques) and silvery scales. Plaques can show up anywhere on the skin, but most often they appear on the knees, elbows, lower back, and scalp. They can be itchy and painful, and they may crack and bleed.
• Guttate psoriasis most often affects people younger than 30. It often shows up following an illness, especially strep throat. This type of psoriasis causes small red spots to appear on the skin, usually on a person's torso, arms, and legs. Spots can also show up on the face, scalp, and ears.
• Inverse psoriasis causes smooth, raw-looking patches of red skin that feel sore. The patches develop in places where skin is touching skin, such as the armpits, buttocks, upper eyelids, groin and genitals, or under a woman's breasts. Being overweight increases a person's risk of developing inverse psoriasis.
• Pustular psoriasis causes the skin to become red, itchy, swollen, and covered with pus-filled bumps — usually on the soles of the feet or the palms of the hand. If pustular psoriasis covers more of the body, a person may sometimes get a fever, chills, and feel tired. This type of psoriasis is less common.
• Erythrodermic psoriasis is rare. With erythrodermic (pronounced: uh-ree-throw-dur-mic) psoriasis, a bright red sunburn-like rash will cover large areas of the body. In addition to itching and possibly pain, someone with this type of psoriasis may notice a fast heartbeat and changes in body temperature.

How Do Doctors Diagnose Psoriasis?

If you think you might have psoriasis, it's a good idea to see a doctor. He or she will look at your skin, scalp, and nails. The doctor will also ask questions — if anyone in your family has psoriasis, if you've been ill recently, or if you've started a new medication.

Occasionally, the doctor may remove a sample of skin (known as a biopsy) to examine it more closely. A biopsy can help doctors decide whether someone has psoriasis or another condition with similar symptoms.

How Is Psoriasis Treated?

There are lots of ways to treat psoriasis. Different treatments work for different people, so doctors often try a few to find the one that works best:

• Creams, lotions, and ointments. Moisturizers, prescription creams (like corticosteroids), vitamin D creams, shampoos made with salicylic acid, and coal tar can effectively treat many types of mild to moderate psoriasis.
• Light therapy (also known as phototherapy). Sunlight or artificial ultraviolet light can sometimes help treat the symptoms of psoriasis. A doctor may recommend going outside for short periods — though too much sunlight can make psoriasis worse, so this option doesn't work for everyone. Doctors may also prescribe special light treatments.
• Pills or injected medications. Doctors usually prescribe these treatments for severe psoriasis or psoriasis that doesn't respond to other treatments. They include pills, shots, and medications given intravenously. Because these treatments can have side effects, doctors usually give them for short periods of time only.

A doctor might try one therapy for a while and then switch to another. Or a doctor may combine different therapies. It's all about finding one that works for each person.

Sometimes what works for a while might stop working. This is one reason why it's important to work closely with a doctor. Trying out new treatments can get a little frustrating, but most people eventually find one that works.

Making healthy choices can help with psoriasis. Here are some things you can do:

• If you smoke, quit. Smoking can trigger outbreaks of psoriasis in some people.
• Avoid alcohol. It can make psoriasis treatments less effective.
• Eat healthy foods. Eating a lot of fruits and vegetables can help fend off diseases that might trigger psoriasis.
• Stay at a healthy weight. This decreases the risk of inverse psoriasis.
• Keep skin clean and well moisturized. Bathing daily with bath salts or oils and then applying moisturizer can help ease the symptoms of psoriasis.

People who have psoriasis may feel self-conscious about how it looks. That's one reason why some people turn to a trained therapist or join a support group of people who understand what they might be going through.

The key to psoriasis treatment is keeping up on whatever your doctor prescribes. If that means applying an ointment twice a day, then find a way to remind yourself to do it (like setting an alarm on your phone) so you don't forget. Psoriasis is one of those things that you need to stay focused on treating, even when you're feeling OK.

Reviewed by: Patrice Hyde, MD
Date reviewed: December 2011