About SJIA About SJIA

What is SJIA?

Many people think that arthritis affects only adults. But the truth is that people of all ages, including children, can experience many different types of arthritis. When arthritis does occur in children, it's commonly referred to as juvenile arthritis.

But what is Systemic Juvenile Idiopathic Arthritis (SJIA)? And how is it different from other types of juvenile arthritis? To get an idea, let's break down the meaning of SJIA:


Systemic means inflammation that affects the entire body.


Juvenile means that it occurs in a young person, or a group of young people.


Idiopathic means the exact cause of the disease is unknown.


Arthritis means that there's inflammation of one or more joints, which can cause pain, swelling, stiffness, and loss of motion.

SJIA is an autoinflammatory disorder which can be caused by having too much of or being too sensitive to certain proteins, including IL-1β, and can lead to symptoms such as fever, rash, headache, feeling very tired (fatigue), or painful joints and muscles. SJIA is a type of Still's disease.

About 300,000 kids* in the United States have some form of arthritis. The most common type of arthritis in kids is juvenile idiopathic arthritis. SJIA accounts for about 10%-20% of all cases of juvenile idiopathic arthritis.

*Estimate based on data obtained between 2001 and 2004.

If your child is diagnosed with SJIA, ask your child's doctor about ILARIS®, the once-monthly injectable biologic medicine that's FDA approved for Still's disease, including SJIA in children 2 years of age and older. Find out more about ILARIS and whether ILARIS is right for your child.

Next: Signs and Symptoms