Adult-onset Still’s disease (AOSD) is a rare condition affecting about one in every 100,000 adults. There is also a pediatric version called systemic onset juvenile inflammatory arthritis (SoJIA).

AOSD is classified as an inflammatory illness that often causes fatigue and swelling in joints, tissues, organs, and lymph nodes. The primary symptoms include:

  • high fevers
  • joint pain
  • salmon-colored rash

The condition is characterized by episodes of flare-up and remission. The disease can appear or disappear suddenly and never come back. In some cases there may only be one episode. In others, an episode may not recur until years later, or there may be multiple episodes within a few months.

AOSD typically presents with a fever that lasts for several days and increases during the night. Along with this fever, you might experience a quick-changing rash on your skin, similar to hives.

Other symptoms of AOSD include:

  • sore throat
  • swollen and tender joints
  • inflamed or swollen lymph nodes
  • muscle pain
  • abdominal pain
  • pain associated with deep breathing
  • weight loss

In some extreme cases, individuals develop an enlarged liver or spleen. The tissues around major organs like the heart and lungs may also become inflamed. However, this complication is rare.

People between the ages of 15 and 46 are at a higher risk for AOSD. People within the age groups of 15 to 25 and 36 to 46 are particularly at risk. Men and women are equally affected.

The causes of adult Still’s disease are still unknown. The condition may be related to certain antigens, substances that cause your body to produce antibodies to fight infection.

It may take multiple tests for your doctor to find the correct diagnosis. Certain types of cancer, mononucleosis, and other conditions, such as Lyme disease, that share many initial symptoms with Still’s disease will need to be ruled out. Also, a blood test may be done to check the level of ferritin, which is often elevated in AOSD.

The three initial symptoms that could indicate AOSD include:

  • fever
  • rash
  • joint pain

Your doctor will follow up by using additional blood test results to learn more about the inflammation in your joints and to help develop a treatment plan.

Your doctor will also listen to your heart and lungs, and may use radiology tests to examine your chest, liver, and spleen.

Because initial symptoms of AOSD are often followed by the onset of arthritis, doctors will usually focus treatment on addressing the arthritis. The most common treatment is a short course of prednisone.

Side effects can include high blood pressure and fluid retention, so your doctor may limit usage. If your AOSD becomes chronic, drugs that modulate your immune system might be necessary. These include:

  • tocilizumab (Actemra) blocks IL-6
  • anakinra (Kineret) blocks IL-1
  • methotrexate (Rheumatrex) blocks dividing cells
  • etanercept (Enbrel), infliximab (Remicade), adalimumab (Humira) block TNF alpha

These drugs are also used to treat inflammatory arthritis, such as rheumatoid arthritis, because they will lower the doses of corticosteroids that are needed.

Self-care for adults with AOSD includes consistent administration of prescribed medications. Exercise can help maintain muscle and joint strength. Your doctor will likely suggest a general exercise plan for you.

You may also be advised to take vitamin supplements, such as calcium and vitamin D, to help prevent osteoporosis, particularly if taking prednisone.

Although there is no cure for AOSD, it is treatable. If symptoms recur, treatment will help to manage inflammation.

A small number of patients with AOSD will develop chronic arthritis with joint symptoms persisting for years. However, medications and self-care can help.

Talk with your doctor about what options would be most effective in treating and managing your specific AOSD symptoms.