Juvenile Idiopathic Arthritis Symptoms & Causes


It’s natural for parents to want to learn as much as possible about any disease their child is facing. In the case of juvenile idiopathic arthritis, however, things can quickly get confusing. JIA is an umbrella term for several kinds of arthritis, each with its own unique features. Moreover, there are different ways to classify these conditions -- and JIA itself is often called by its old name, JRA (juvenile rheumatoid arthritis).

A good place to start, then, is to simply understand what is happening in your child’s body.

  • Like everyone else, your child has an immune system, a group of organs and cells that work together to fight off outside invaders like germs and viruses.
  • In autoimmune diseases, like JIA, something causes the immune system to begin attacking the body’s healthy cells and tissues.
  • In JIA, the immune system targets the synovium, a special tissue that lines the joints and provides nourishment and lubrication for the cartilage (the “Teflon” cushion that covers the bones where they meet).
  • The immune system’s attack causes the synovium -- which is normally too thin to feel -- to become swollen and “angry,” or inflamed, and the affected joint to become swollen, stiff and sore.
  • If untreated, the inflammation can eat away at the cartilage and surrounding bone. Frequently, it can also affect the way a child’s bones grow, sometimes permanently.
  • In JIA, inflammation can affect joints in any part of the body. It may also affect other tissues and organs, especially the eyes.
  • Typically, there are times when the inflammation goes into remission (gets better or disappears), and times when it flares (gets worse).

The number and kinds of joints affected, as well as other associated symptoms, help doctors determine what kind of JIA your child has. There are three main subtypes:

1.       Oligoarticular JIA involves four joints or fewer (“oligo” means “few”) and:

  • is most common and often the mildest type of JIA
  • is sometimes also called pauciarticular JIA (“pauci” is another word for “few”)
  • accounts for about 60 percent of children with JIA, mostly girls
  • typically begins between the ages of 1 and 5
  • tends to involve large joints, such as the knees, ankles and elbows
  • carries the highest risk for eye inflammation (uveitis)
  • sometimes spreads to multiple joints; this is called “extended” oligoarticular JIA, and is more similar to polyarticular JIA

2.       Polyarticular JIA involves five or more joints (“poly” means “many”) and:

  • accounts for about 20 percent of children with JIA, mostly girls
  • can begin at any age
  • tends to involve the small joints, such as the hands and feet, but can also include the hips, shoulders, neck and jaw
  • is divided into two types, depending whether there’s a certain antibody in the blood: rheumatoid factor negative and rheumatoid factor positive; the latter is typically found in teens and closely resembles adult rheumatoid arthritis

3.       Systemic JIA involves the body as a whole (this is what “systemic” means) and:

  • is the least common and potentially most serious form of JIA
  • is sometimes called Still’s disease
  • accounts for about 10 percent of children with JIA, boys and girls equally
  • can begin at any age
  • tends to involve the small joints of the hands, wrists, knees and ankles, and sometimes internal organs including the heart, liver, spleen and lymph nodes
  • its symptoms initially include spiking fevers and rashes; the arthritis may not develop until weeks or months later

Other subtypes of JIA you may hear about include psoriatic arthritis and enthesitis-related arthritis, which involves inflammation where tendons and ligaments attach to bone (one example is ankylosing spondylitis. There’s even an “undifferentiated arthritis” category for conditions that don’t fit into the other subtypes.

But don’t let yourself get all turned around trying to sort out the categories. Your child’s physician will discuss in detail with you what kind of JIA your child has and why it has a particular name. The main point is that you and your physician should be committed to getting rid of the arthritis entirely in order to let your child’s joints grow well.

Who is at risk?

It’s true that certain types of juvenile idiopathic arthritis tend to occur in different groups of children. But when taken as a whole, JIA has three basic risk factors:

  • Age: JIA affects children from infancy to age 16, though rarely when babies are younger than 6 months old. Children at the highest risk are 2 to 3 years old.
  • Gender: Girls are more than twice as likely as boys to have JIA.
  • Genetics: Children with a family member with JIA or another autoimmune disease are more likely to have JIA. However, the risk factor is low enough that it’s extremely rare that two kids in any one family will have JIA.


While juvenile idiopathic arthritis can’t be prevented, early diagnosis and treatment go a long way toward preventing its potentially serious complications. You and your child also play an important role, by making sure to understand and follow the recommendations of your child’s health care team.

In a chronic illness like JIA, it can be very challenging to keep up with your child’s appointments and medication schedule, as well as things like physical and occupational therapy sessions. But by doing so -- literally “following doctor’s orders” -- you will ensure the best possible outcome for your child.


One of the biggest ways that juvenile arthritis differs from adult arthritis is its potential to harm a child’s still-growing bones and tissues. While most children with JIA will do well in the long run, doctors watch this disease very closely -- and treat it aggressively -- because the inflammation of arthritis can have serious consequences for a child’s growing body. These may include:

  • stunted overall growth
  • bones that grow too short or too long
  • jaw growth problems (which can also lead to dental problems, because it can be hard to brush and floss properly)
  • wearing away or destruction of joints
  • inflammation of membranes surrounding the heart or lungs
  • vision loss from chronic eye inflammation (uveitis)
  • increased risk for osteoarthritis and osteoporosis in adulthood
  • sudden hyperactivity of the immune system called macrophage-activation syndrome (an extremely rare, potentially life-threatening problem that occurs only in systemic JIA)

To prevent these complications, you and your child’s rheumatologist will need to work together to make sure that all evidence of inflammation is gone. With successful therapy, you should expect that your child barely notices he has JIA. If you find that your child still has swollen joints, limp or other symptoms, be sure to bring this to the attention of your doctor. Don’t try to “tough it out” -- your child’s joints have years of service ahead of them, and need to remain in perfect condition to bear the stresses and strains of everything that your child will put them through.

Long-term outlook

For families dealing with juvenile idiopathic arthritis 15 or 20 years ago, there was a lot to be afraid of. But nowadays, with active care and highly effective treatments, the large majority of kids with JIA can expect to lead very normal lives.

About half of children will “outgrow” their diseases (that is, it goes into full remission without need for medications), while others continue to need treatment as adults. A lot depends on what type of JIA your child has: Oligoarticular JIA that stays in just a few joints, for instance, goes into remission about 75 percent of the time, while polyarticular JIA that’s rheumatoid factor positive rarely goes into remission.

It’s impossible to predict exactly what will happen with your child. But after identifying the distinct pattern of your child’s JIA, your health care team will be able to give you a general idea of the future.


Even though we know a great deal about JIA and how to treat it, what causes this disease -- and why it happens to some children and not others -- remains a mystery. JIA is thought to be a “multifactorial” disease, which means a number of things have to come together to cause it. Research suggests a mix of genetic and environmental factors: Something in a child’s genes may make him susceptible to JIA, but something else has to happen (an infection, for example) to set it off. Children’s Hospital Boston is now involved in research efforts that are trying to get to the root of childhood arthritis.


Juvenile idiopathic arthritis is never the same from one child to the next. Symptoms may come and go, or may be continuous. They may occur first in one part of the body, and then another.

Surprisingly, one thing that holds true for JIA is that joint pain is rarely among its initial symptoms. In fact, if your child complains that one or more of his joints hurt, he probably doesn’t have arthritis, but another illness instead.

Some of the most common symptoms of JIA include:

  • stiffness and swelling in the joints, especially in the morning or after a nap
  • limping (because the knees and ankles are the most commonly affected joints in JIA)
  • favoring one limb over another (e.g., using the right arm more than the left)
  • excessive clumsiness
  • fatigue or irritability
  • decreased appetite, poor weight gain and slow growth

There are also distinct symptoms for systemic JIA, which affects not only the joints but the body as a whole. These include:

  • spiking fevers, usually every day
  • rash that comes and goes with the fever
  • swollen lymph nodes (glands)

JIA can also sometimes cause eye inflammation, called uveitis. This problem can occur without any eye symptoms, or may cause eye redness, eye pain, increased pain when looking at light (photophobia) and vision changes.


Q: Why did my child get arthritis?
Though we don’t yet understand why JIA occurs, researchers believe there’s a mix of unknown genetic and environmental factors at work. It’s nobody’s fault when a child develops JIA -- parents can’t do anything to cause it or prevent it.

Q: Is there any way to screen for JIA?
No test can show how likely a child is to develop JIA. In addition, no test can prove a child has JIA; instead, JIA is a “diagnosis of exclusion,” meaning the doctor will work to rule out other causes of your child’s symptoms, mainly through a thorough physical exam.

Q: Are my other children at risk for developing JIA?
While JIA has a tendency to run in families, it’s not a strongly hereditary disease (something parents pass directly along to their children, like hemophilia). The risk of having two children with JIA in one family is extremely low.

Q: Can children outgrow JIA?
With proper treatment and care, about half of kids with JIA do indeed “outgrow” it -- meaning the illness goes into full remission -- with few or no lasting effects. However, this depends a good deal on what kind of JIA a child has, and there’s no test that can predict which children will eventually free themselves of arthritis.

Q: If JIA lasts into adulthood, is it considered adult arthritis?
If your child was younger than 16 when her symptoms started, her illness will always be juvenile idiopathic arthritis, no matter how old she gets. In fact, Children’s Hospital Boston treats a number of JIA patients into early adulthood.

Q: Does arthritis mean my child won’t be able to play sports?
Exercise is essential for children with JIA, to help keep the joints mobile and the muscles strong. If joint inflammation is controlled early, most children can return to full normal activities, and some of our patients are exceptional athletes. In some patients, however, trauma can trigger a “flare” of arthritis and your physician may recommend sports that don’t put too much stress on joints, like swimming.

Q: If my child has severe JIA, is there a chance she may eventually need a wheelchair?
Very few children have arthritis to such a severe degree that a wheelchair becomes necessary. The best way to avoid this is to work together closely with your doctor and make sure that your child is receiving treatment as directed. If your child’s disease is incompletely controlled, make sure your doctor knows this so that therapy can be changed.

Questions to ask your doctor

You and your family are key players in your child’s medical care. It’s important that you share your observations and ideas with your child’s health care provider, and that you understand your provider’s recommendations.

If your child is suffering from arthritis and you’ve set up an appointment, you probably already have some ideas and questions on your mind. But at the appointment, it can be easy to forget the questions you wanted to ask. It’s often helpful to jot them down ahead of time so that you can leave the appointment feeling that you have the information you need.

If your child is old enough, you may want to suggest that she write down what she wants to ask her health care provider, too.

Some of the questions you may want to ask include:

  • What kind of arthritis are we dealing with?
  • How is it affecting my child’s body?
  • What is the long-term outlook for my child?
  • Who will be involved in my child’s health care?
  • What are our treatment options?
  • What are the possible side effects?
  • How will we know whether the treatment is working?
  • How will arthritis affect my child’s day-to-day life?
  • What can I do to help support my child’s health and help her cope with her condition?

For teens

Having arthritis as a teenager can seem especially tough. You’re heading into a very important time at school, with decisions to be made about college and your future. Your body is already going through a lot of changes. You may be dealing with dating, peer pressure, learning how to drive -- add the day-to-day challenges of a chronic illness like JIA, and it can be a lot to handle!

It helps to remember that most teens with JIA do the same stuff as other teens, like going to school, doing chores and hanging out with their friends. Plus, you’ll have a lot of backup: Doctors, counselors, physical therapists and other members of your treatment team are all there to support you.

Take charge of your health: As you get older, you’ll be taking on more responsibility for managing your JIA -- keeping up with medications, sticking to an exercise routine, eating a healthy diet. Though it may seem overwhelming at first, you may find that you feel more in control of your disease, not the other way around.

Find smart strategies for school: Having JIA may make it difficult to get up and around, so give yourself extra time to get to school and to change classes. Plan stretch breaks to relieve stiffness. These and other coping tricks can take some of the stress out of juggling your illness and your education. Plus, you may be eligible for something called a 504 plan, which lays out what kinds of support you need from teachers and school administrators -- like providing an extra set of textbooks, so you don’t have to lug a heavy backpack between home and school.

Don’t hide how you feel: Some days you’re just going to feel angry or depressed about having JIA. That’s normal, and being able to talk to your friends or family can help you through the rough patches. But -- especially if these feelings don’t go away -- you may also want to talk with a counselor or therapist. A positive mental outlook is just as important as exercise and a healthy diet in beating JIA.

Talk to someone who’s been there: Connecting with other teens with JIA is a great way to not only make new friends, but also to pick up tips and strategies for dealing with your illness. Ask your doctor if you might be able to meet up with another patient your age, or check out the Arthritis Foundation web site (www.arthritis.org) for info on events for teens and local support groups.



Antibody: A special protein produced by the body's immune system that recognizes and helps fight viruses, bacteria and other foreign substances (antigens) that invade the body. Abnormal antibodies that attack the body itself are called autoantibodies.

Antinuclear antibody (ANA): A type of autoantibody directed against the nuclei of healthy cells. Because these antibodies can be found in the blood of children with JIA, testing for them can be useful in diagnosis.

Arthritis: Inflammation of a joint, usually accompanied by pain, swelling and sometimes a change in structure.

Autoimmune diseases: A host of diseases, including JIA, that are caused by the immune system mistakenly attacking the body’s own cells, tissues and organs.

Biologics: A relatively new class of medications used in arthritis treatment that are based on compounds made by living cells. These compounds modify the action of the immune system by blocking chemicals that fuel inflammation and tissue destruction.

Cartilage: A connective tissue that covers the ends of bones in a joint. Cartilage helps cushion the pressure of bone on bone while also allowing bones to slide over one another easily.

Corticosteroids: Powerful anti-inflammatory drugs that can be taken by mouth or intravenously, or injected directly into the affected joints to temporarily suppress the inflammation.

Disease-modifying anti-rheumatic drugs (DMARDs): A class of medications that can slow or potentially stop the activity of JIA, often by suppressing the overactive immune system.

Enthesis: Site of attachment of ligament or tendon to bone. Inflammation of an enthesis is called enthesitis.

Flare: A period in the course of disease in which symptoms become worse. In most children, JIA is characterized by periods of remission punctuated by flares.

Idiopathic: Of unknown cause or explanation.

Inflammation: A normal reaction by the body to injury or disease, which results in swelling, redness, pain and swelling.This can occur anywhere, not only in joints.

Immune system: A collection of cells and proteins that works to protect the body from potentially harmful, infectious microorganisms, such as bacteria and viruses.

Intra-articular: Into or within a joint; for example, an intra-articular injection.

Joint: Where the ends of two or more bones meet. Most joints are composed of cartilage, joint space, fibrous capsule, synovium and ligaments.

Ligaments: A stretchy band of fibrous tissue that binds joints together and connects various bones and cartilage.

Nonsteroidal anti-inflammatory drugs (NSAIDs): A class of medications that work to reduce pain, fever and inflammation by blocking substances called prostaglandins. Some of the most common include ibuprofen (Motrin) and naproxen (Aleve).

Oligoarticular JIA: A type of JIA that affects four or fewer joints; formerly known as pauciarticular juvenile rheumatoid arthritis.

Polyarticular JIA: A type of JIA that affects five or more joints; formerly known as polyarticular juvenile rheumatoid arthritis.

Remission: A period when the symptoms of JIA improve or disappear completely. Sometimes remission is permanent, but more often it is punctuated by flares of the disease.

Rheumatoid factor: An antibody that is found often in the blood of adults with rheumatoid arthritis and once in a while in children with JIA. For these children, testing for the antibody may be useful as a diagnostic tool.

Soft tissue: The parts of the body that are not bone. In the musculoskeletal system, these include ligaments, tendons and muscles.

Synovial fluid: A thick fluid released by the synovial membrane that acts to nourish cartilage and lubricate for joints and tendons.

Synovium: A tissue that lines and seals the joint and releases a fluid that allows the joint to move easily; also called synovial membrane. Inflammation of the synovium is called synovitis.

Systemic: Refers to a disease that can affect the whole body, rather than just a specific organ or joints.

Systemic JIA: A type of JIA that can affect internal organs as well as joints; also called systemic-onset juvenile rheumatoid arthritis.

“Helping Your Child with Medical Experiences: A Practical Parent Guide”

Download a free booklet, “Helping Your Child with Medical Experiences: A Practical Parent Guide”. (Please note that Adobe Acrobat is required.) and read about topics including: 

  • talking to your child about his condition
  • preparing for surgery and hospitalization
  • supporting siblings
  • taking care of yourself during your child’s illness
  • adjusting to life after treatment