What is juvenile idiopathic arthritis (JIA)?

Juvenile idiopathic arthritis (JIA) is the most common type of chronic, or long-lasting, arthritis that affects children. It happens when the immune system attacks healthy joint tissues.

JIA broadly refers to several different chronic (long-lasting) disorders involving inflammation of joints (arthritis), which can cause:

  • Joint pain.
  • Swelling.
  • Warmth.
  • Stiffness.
  • Loss of motion.

JIA may last a  few months or years, or it may be a lifelong disease.

Who gets juvenile idiopathic arthritis (JIA)?

JIA begins in children and adolescents before they turn 16. Most types of the disease are more frequent in girls, but others affect boys more frequently or affect boys and girls equally. Children of all races and ethnic backgrounds can get the disease.

Though JIA does not tend to run in families, children with a family member who has long-lasting arthritis, including JIA, are at a slightly increased risk of developing it.

What are the types of juvenile idiopathic arthritis (JIA)?

There are multiple types of JIA, each with different features. Generally, they all share symptoms of joint pain, swelling, warmth, and stiffness that last at least 6 weeks.

What are the symptoms of juvenile idiopathic arthritis (JIA)?

Symptoms of JIA vary depending on the type, but all forms share persistent joint pain, swelling, warmth, and stiffness that are typically worse in the morning and after a nap or prolonged sitting.

Many children, especially younger ones, will not complain of pain. One of the earliest signs may be limping in the morning due to disease in one or both legs.

The symptoms of JIA may get worse (flares) for a few weeks or months, followed by times when they get better. Some children have just one or two flares and never have symptoms again, while others have many flares or symptoms that never fully go away.

Besides joint problems, the inflammation associated with JIA can cause other symptoms, such as:

  • Eye inflammation. It is important for children with JIA to have frequent eye exams because this inflammation can lead to eye problems and vision loss.
  • Skin changes, such as rashes.
  • Fever.
  • Growth problems.

What causes juvenile idiopathic arthritis (JIA)?

In JIA, the body’s immune system—which normally helps to fight off infections and heal cuts and wounds—mistakenly attacks some of its own healthy cells and tissues. The result is inflammation, causing pain, swelling, warmth, and stiffness.

Doctors do not know why the immune system attacks healthy tissues in children with JIA, but they believe that a mix of genes and environmental factors are involved.