What Causes Psoriatic Arthritis (PsA)?

While the direct cause of PsA is unknown, here's what we do know: First, you may be more likely to experience PsA if it's part of your family's medical history. Second, PsA symptoms begin when your immune system attacks healthy cells in your body, for reasons we do not yet understand.

Normally, the immune system (the body's natural defense system) protects your body from bacteria, viruses, or other foreign agents. When you have PsA, your immune system incorrectly attacks the linings of the joints and skin. This causes uncontrolled inflammation—leading to the joint and skin symptoms usually experienced with PsA.

Who gets PsA?

  • Approximately 15% of people with psoriasis can develop PsA
  • PsA affects men and women equally
  • The disease can appear at any age, but usually occurs in people between the ages of 30 and 50

In many patients, joint symptoms can develop before skin symptoms appear. A rheumatologist or a dermatologist can determine if your symptoms are due to PsA. Rheumatologists are physicians who focus on treating arthritis and other joint diseases, while dermatologists are physicians who specialize in treating skin conditions. If you receive a diagnosis of active PsA, your rheumatologist may prescribe REMICADE® as part of your treatment plan.

Symptoms and diagnosis

If you experience any of the following symptoms of PsA, talk to a rheumatologist (arthritis specialist) as soon as possible.

Joint symptoms

PsA usually affects the finger and toe joints, but you may also experience symptoms in the lower back and heels. Some other characteristics of PsA include:

  • Dactylitis (dak'-ti-li'tis), or inflammation and swelling in the joints at the ends of fingers or toes
  • Enthesitis (en'-the-si'-tis),or inflammation in the tendons or ligaments and can occur at the heel

Skin symptoms

In PsA, uncontrolled inflammation can lead to the body producing too many skin cells. When the body produces too many of these cells, you can also get skin lesions. These lesions are areas of red patches covered by red and white scaly skin. They can occur anywhere on the body.

PsA and RA

Because the symptoms of PsA may resemble those of rheumatoid arthritis (RA), doctors may first look for scaly skin lesions. Since there is no simple test for determining whether you may have RA versus PsA, your doctor may look for cell abnormalities by examining a skin sample under a microscope. Typically, skin symptoms of PsA will appear before the arthritis associated with PsA. Blood tests and x-ray or MRI studies may also help confirm a diagnosis.

Take a closer look at PsA

When you have psoriasis and PsA, you have a skin condition that is marked by a rapid buildup of dry, dead skin cells that form thick scales.

In psoriatic arthritis, underlying inflammation leads to overproduction of your skin cells:

Click to enlarge image

Click to enlarge image

PsA also affects your joints, causing lasting pain, stiffness, and swelling. Since PsA is a progressive disease, this often leads to loss of movement and joint damage, particularly if left untreated.

Joint with psoriatic arthritis:

Click to enlarge image

While the skin symptoms of PsA may be easy to identify, you can't see the joint damage caused by PsA. Over time, this can severely limit your ability to move. That's why it's important to see a dermatologist or rheumatologist immediately if you think you may be experiencing symptoms that resemble active PsA. If you are diagnosed with active PsA, your doctor may prescribe REMICADE® to help relieve your skin and joint symptoms and help stop further joint damage.

NEXT: Treatment Options


Only your doctor can recommend a course of treatment after checking your health condition. REMICADE® (infliximab) can cause serious side effects such as lowering your ability to fight infections. Some patients, especially those 65 years and older, have had serious infections caused by viruses, fungi or bacteria that have spread throughout the body, including tuberculosis (TB) and histoplasmosis. Some of these infections have been fatal. Your doctor should monitor you closely for signs and symptoms of TB during treatment with REMICADE®.

Unusual cancers have been reported in children and teenage patients taking TNF-blocker medicines. Hepatosplenic T-cell lymphoma, a rare form of fatal lymphoma, has occurred mostly in teenage or young adult males with Crohn’s disease or ulcerative colitis who were taking REMICADE® and azathioprine or 6-mercaptopurine. For children and adults taking TNF blockers, including REMICADE®, the chances of getting lymphoma or other cancers may increase.

You should discuss any concerns about your health and medical care with your doctor.

What should I tell my doctor before I take REMICADE®?

You should let your doctor know if you have or ever had any of the following:

  • Tuberculosis (TB) or have been near someone who has TB. Your doctor will check you for TB with a skin test. If you have latent (inactive) TB, you will begin TB treatment before you start REMICADE®.
  • Lived in a region where certain fungal infections like histoplasmosis or coccidioidomycosis are common.
  • Infections that keep coming back, have diabetes or an immune system problem.
  • Any type of cancer or a risk factor for developing cancer, for example, chronic obstructive pulmonary disease (COPD) or had phototherapy for psoriasis.
  • Heart failure or any heart condition. Many people with heart failure should not take REMICADE®.
  • Hepatitis B virus (HBV) infection or think you may be a carrier of HBV. Your doctor will test you for HBV.
  • Nervous system disorders (like multiple sclerosis or Guillain-Barré syndrome).

Also tell your doctor if you:

  • Use the medicines Kineret (anakinra), Orencia (abatacept) or Actemra (tocilizumab) or other medicines called biologics used to treat the same problems as REMICADE®.
  • Are pregnant, plan to become pregnant, are breast-feeding, or have a baby and were using REMICADE® during your pregnancy. Tell your baby’s doctor about your REMICADE® use before the baby receives any vaccine because of an increased risk of infection for up to 6 months after your last dose of REMICADE® you received during your pregnancy.
  • Recently received or are scheduled to receive a vaccine. Adults and children taking REMICADE® should not receive live vaccines or treatment with a weakened bacteria (such as BCG for bladder cancer) while taking REMICADE®.

What should I watch for and talk to my doctor about before or while taking REMICADE®?

The following serious (sometimes fatal) side effects have been reported in people taking REMICADE®.

You should tell your doctor right away if you have any of the signs listed below:

  • Infections (like TB, blood infections, pneumonia)—fever, tiredness, cough, flu, or warm, red or painful skin or any open sores. REMICADE® can make you more likely to get an infection or make any infection that you have worse.
  • Lymphoma, or any other cancers in adults and children.
  • Skin cancer—any changes in or growths on your skin.
  • Heart failure—new or worsening symptoms, such as shortness of breath, swelling of your ankles or feet, or sudden weight gain.
  • Reactivation of HBV—feeling unwell, poor appetite, tiredness, fever, skin rash and/or joint pain.
  • Liver injury—jaundice (yellow skin and eyes), dark brown urine, right-sided abdominal pain, fever, or severe tiredness.
  • Blood disorders—fever that doesn’t go away, bruising, bleeding or severe paleness.
  • Nervous system disorders—numbness, weakness, tingling, changes in your vision or seizures.
  • Allergic reactions during or after the infusion—hives, difficulty breathing, chest pain, high or low blood pressure, swelling of face and hands, and fever or chills.
  • Lupus-like syndrome—chest discomfort or pain that does not go away, shortness of breath, joint pain, rash on the cheeks or arms that gets worse in the sun. The more common side effects with REMICADE® are respiratory infections (that may include sinus infections and sore throat), headache, rash, coughing and stomach pain.
  • Psoriasis—new or worsening psoriasis such as red scaly patches or raised bumps on the skin that are filled with pus.

Please read the accompanying Medication Guide for REMICADE® and talk with your doctor. You are encouraged to report negative side effects of prescription drugs to the FDA.

Visit www.fda.gov/medwatch, or call 1-800-FDA-1088.