If you’ve been diagnosed with Sjögren’s disease, you may be surprised to learn that you could also be diagnosed with one or more overlapping diseases and conditions. Rheumatoid arthritis (RA), in particular, occurs alongside Sjögren’s and often includes similar symptoms, such as joint swelling, joint pain, and fatigue. Because of these similarities, it’s easy for healthcare providers to miss one of these conditions early on or even misdiagnose them at first.

It’s important to identify the underlying causes of your symptoms. This way, your healthcare provider can put together a comprehensive treatment plan that prevents complications and improves your quality of life. It also ensures that you receive individualized treatment, such as getting input from an ophthalmologist and a dentist to address both dry mouth and dry eyes that can occur with Sjögren’s disease.

One way to ensure you know the cause of your symptoms and get comprehensive treatment is to follow up with your healthcare provider and advocate for yourself. To advocate for yourself and ask if additional testing is needed, it’s important to know more about overlapping diseases like rheumatoid arthritis, including its similarities to Sjögren’s. Here are nine ways the two conditions are connected and what you need to know about each.

1. Sjögren’s and RA Are Both Autoimmune Conditions

Both Sjögren’s disease and rheumatoid arthritis are autoimmune diseases. In autoimmune conditions, the immune system mistakenly attacks your body’s tissues and organs rather than directing its efforts at substances like viruses and germs.

Scientists aren’t exactly sure what causes Sjögren’s disease and RA. Some believe that certain people are born with genes that make them more likely to get these diseases, especially if something in their environment — like a virus or infection — triggers it. About 12 out of every 100 people with Sjögren’s have a family member who also has the disease. Many medical experts think RA happens because of a mix of genes and lifestyle choices.

2. Sjögren’s and RA Both Cause Systemic Inflammation

Sjögren’s disease and RA are considered systemic inflammatory diseases and can affect other organs or systems in your body outside of the ones they initially affect. With RA, you may experience swollen joints and stiffness in your hands and feet, but this condition can also impact your nerves and the lining of your heart.

Sjögren’s initially affects your eyes and mouth and may require artificial tears, eye drops, and medications that encourage saliva production. But the condition can also cause inflammation in your peripheral nervous system (the nerves and neurons outside of your brain and spinal cord) and your central nervous system (your body’s primary command center, including the brain and spinal cord).

3. Sjögren’s and RA Share Similar Blood Test Markers

Sjögren’s disease and RA are diagnosed using blood tests that look for autoantibodies. Physical exams, medical history, and imaging are also used to make a diagnosis. A blood test to look for rheumatoid factor is used for both conditions. About 80 percent of people with RA have a positive blood test for rheumatoid factor, while 75 percent to 95 percent of people with Sjögren’s disease test positive.

Healthcare providers may also use the anti-Sjögrens-syndrome-related antigen A (anti-SSA) test, or anti-Ro test, and the antinuclear antibody (ANA) test. More than half of people with Sjögren’s disease have a positive anti-SSA test. People who have both RA and Sjögren’s can also have a positive anti-SSA test. Most people with Sjögren’s disease get a positive result on the ANA test. One study found that about 4 out of 10 people with RA also had a positive ANA test.

4. Sjögren’s and RA Are More Common in Women

Rheumatoid arthritis and Sjögren’s are more common in women. In fact, Johns Hopkins Medicine reports that women are 10 times more likely than men to develop Sjögren’s disease. Nine out of 10 people living with the condition are women.

The U.S. Centers for Disease Control and Prevention (CDC) reports that women are two to three times more likely than men to develop RA. Some scientists believe that hormones like estrogen may play a role in RA, while others believe that the differences in how men’s and women’s immune systems function may contribute.

5. Sjögren’s and RA Have Overlapping Symptoms and Comorbidities

Rheumatoid arthritis and Sjögren’s have some overlapping symptoms, including:

• Joint pain and stiffness
• Fatigue
• Skin rashes
• Inflammation

They also have comorbidities (related conditions) in common. For instance, people with RA and Sjögren’s are more likely to develop secondary Raynaud phenomenon.

Likewise, people with RA and Sjögren’s are at an increased risk of developing scleroderma — another autoimmune disease that causes excess scar tissue in different organs in the body. About 20 percent of people with scleroderma also have Sjögren’s disease, and up to 5 percent of people with scleroderma also have rheumatoid arthritis.

6. Sjögren’s and RA May Have Shared Risk Factors

Sjögren’s and RA also have some shared risk factors. These include:

• Being 40 or older
• Having a genetic predisposition
• Being exposed to certain environmental factors, like secondhand smoke, air pollution, and other toxins
• Developing infections, like Epstein-Barr virus, Escherichia coli, and hepatitis C
• Having at least one other autoimmune disease

7. Untreated Sjögren’s or RA Can Lead to Complications

While being diagnosed with either Sjögren’s or RA can be overwhelming, if these conditions are caught early, symptoms can be managed. Treating these conditions is important for preventing complications.

Sjögren’s can lead to cognitive impairment and damage to the lungs, thyroid, and liver. Neurological issues like burning toes and feet (neuropathy) can develop in 10 percent to 20 percent of people with Sjögren’s. Rheumatoid arthritis can lead to joint deformity, mobility issues, heart disease, and decreased life expectancy, especially if it’s left untreated.

People with Sjögren’s have a higher risk of lymphoma than the general population, often several times higher overall. The risk can be much higher only in certain high-risk groups with specific warning signs.

8. Sjögren’s and RA Can Be Misdiagnosed

Regardless of the type, autoimmune diseases are often misdiagnosed, especially because so many of their symptoms overlap. In fact, 76 percent of people with an autoimmune condition received at least one misdiagnosis before the correct one. The same is true for RA and Sjögren’s disease, especially because they can both include joint pain and inflammation.

Sjögren’s can often be confused with systemic lupus erythematosus, menopause, allergies, fibromyalgia, and multiple sclerosis. For this reason, it can take upward of three years before a person is diagnosed. Misdiagnosis can happen with RA, but the exact rate varies by clinic and study.

9. Sjögren’s and RA May Be Treated With the Same Drugs

Regardless of whether RA and Sjögren’s occur together or separately, systemic symptoms may be treated with anti-inflammatory drugs or disease-modifying antirheumatic drugs (DMARDs). Biologics, immunosuppressants, and corticosteroids may also be used. These drugs each help manage inflammation and joint pain. For rheumatoid arthritis, the focus is to prevent joint damage, but these drugs can also address systemic inflammation and neuropathy found in Sjögren’s.

Unlike RA, there are currently no U.S. Food and Drug Administration (FDA)-approved disease-modifying drugs specifically for Sjögren’s, although several are being studied in clinical trials. Rheumatology providers may use some of these medicines off-label to treat certain whole-body (systemic) problems in Sjögren’s, but results can vary. Treatments for dry eyes and dry mouth remain standard care.

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If you’ve been diagnosed with both Sjögren’s disease and rheumatoid arthritis, what similarities between the two have you noticed? Let others know in the comments below.