Still’s disease is an immune-related condition that, like rheumatoid arthritis (RA), causes joint pain. But Still’s disease typically appears as a single episode or a series of episodes, while RA is a chronic, lifelong condition.

Mom and daughter at the gym.Share on Pinterest
Getty Images

Still’s disease and rheumatoid arthritis (RA) are two different types of arthritis. While both link to inflammation and may share some similarities, Still’s disease and RA are notthe same conditions.

Read on to learn the key differences between Still’s disease and RA, including symptoms, causes, treatment, and more.

Still’s disease is uncommon. It tends to develop in people between ages 16 and 35. RA is a more common condition that can occur at any age but often develops in people between ages 30 and 50.

While both conditions may relate to the immune system functioning atypically, one key difference between them is that RA is a chronic autoimmune condition, and Still’s disease is not. Still’s disease often presents in a single episode or a series of recurrent episodes. These episodes tend to include acute symptoms, like a high fever, that are uncommon in RA.

RA is an inflammatory condition that causes joint and tissue inflammation. RA is also an autoimmune disease. It happens when your immune system mistakenly attacks healthy cells in your body, most often in the lining of your joints. The resulting inflammation causes joint pain and swelling and sometimes more systemic complications.

Still’s disease is also an inflammatory form of arthritis, but experts consider it more idiopathic, meaning the exact cause is unknown. Some experts believe that an infection may trigger Still’s disease in certain people. Newer research supports the theory that adult-onset Still’s disease is an auto-inflammatory condition that happens when the immune system reacts atypically.

Still’s disease and RA tend to develop in adulthood, it’s also possible for these conditions to develop in children under 16 years old. Experts call these juvenile Still’s disease and juvenile idiopathic arthritis (JIA).

Researchers believe that Still’s disease may actually be an adult form of systemic juvenile idiopathic arthritis (SJIA), a rare form of rheumatoid arthritis in children that affects the joints and other organs. The two conditions follow very similar patterns and share many of the same primary symptoms.

JIA used to be called juvenile rheumatoid arthritis. Experts adopted the term “JIA” as an umbrella term to include other forms of inflammatory arthritis affecting children — including Still’s disease.

Both Still’s disease and RA cause pain in one or more joints. Each may affect only a few joints before becoming more widespread. However, there are key differences in the onset of symptoms.

Still’s disease

With Still’s disease, you may not experience joint pain at first. The onset of this condition typically begins with:

  • a high fever of 102.2°F (39°C) that appears intermittently and may peak twice a day
  • salmon-colored skin rashes, which primarily affect your arms, legs, and trunk
  • sore throat
  • swollen lymph nodes

After a few weeks, you may experience joint and muscle pain that lasts for 2 weeks or longer. People with Still’s disease often feel joint pain in the knees and wrists. Joint pain may increase or affect more joints over time.

The progression of Still’s disease may vary. Symptoms of an episode may last several weeks or months and then go away. Symptoms may never return, or they can come back months or years later. Chronic Still’s disease means that you have long-term symptoms.

Rheumatoid arthritis

RA primarily involves joint pain, stiffness, and swelling. These also tend to develop in a symmetrical pattern, meaning that it affects joints on both sides of your body (for example, both your knees or hands).

Additional symptoms of RA may include:

  • occasional low grade fevers
  • fatigue
  • reduced mobility
  • loss of appetite
  • anemia
  • inflamed heart and lung tissues and blood vessels

There’s no single test doctors can use to diagnose Still’s disease or RA. Instead, a doctor will rely on your symptom history, along with a combination of the following tests:

Physical exam

During a physical exam, a doctor will look for signs of joint inflammation and rashes or fever. They will ask you about your symptoms and how long you’ve experienced them.

A doctor will also review your medical history. For JIA, a doctor may rule out conditions with similar symptoms, such as lupus, Lyme disease, or bone disorders.

Blood tests

While no blood test can confirm RA or Still’s disease, a doctor may consider ordering other blood tests to assess your overall health and rule out other conditions.

One example is a complete blood count test. If you have Still’s disease, this blood test may show high white blood cell and low red blood cell counts. RA and Still’s disease may also show high C-reactive protein levels, which are a marker of inflammation.

A medical professional might also test your blood for rheumatoid factor (RF). While adults with RA may have a positive test result, you may test RF-negative if you have Still’s disease or JIA.

Imaging tests

If a doctor suspects RA or Still’s disease, they may order imaging tests to look for joint inflammation and damage. Examples include an X-ray, ultrasound, and MRI.

Because they are both inflammatory conditions, the treatments for Still’s disease and RA are similar. These may include:

  • Nonsteroidal anti-inflammatory drugs (NSAIDs): People can take over-the-counter medications like ibuprofen (Advil) or naproxen (Aleve) to reduce joint inflammation and pain.
  • Corticosteroids: People can take these medications by mouth or via injection(s). These medications may treat more severe inflammation that doesn’t respond to NSAIDs.
  • Corticosteroid eye drops: These drops may treat uveitis (eye inflammation) that develops in JIA or RA.
  • Disease-modifying drugs: Examples include biologics, and may be necessary to treat severe RA or Still’s disease that becomes chronic.
  • Therapies: Physical and occupational therapy may help improve your range of motion and overall mobility.
  • Surgery: While reserved for more severe cases, joint repair surgery or a joint replacement may help if your arthritis is more advanced and significantly affects your quality of life.

Maintenance therapy, or low dose medications, may be necessary to manage inflammation with Still’s disease. With RA, you may need certain medications over the long term to help prevent joint damage.

Still’s disease and RA are two types of arthritis that may cause inflamed, painful joints and share similarities in diagnosis and treatment.

Experts consider Still’s disease rare, and it may develop in childhood and adulthood. RA, on the other hand, is a common autoimmune disease that primarily develops in adulthood.

To accurately differentiate between Still’s disease and RA, it’s important to talk with a doctor.