Sjögren’s syndrome is a complex autoimmune condition most commonly associated with symptoms like dry eyes and dry mouth. However, what makes it especially unique is how frequently it coexists with other autoimmune diseases. In fact, up to half of all cases are classified as "secondary Sjögren’s syndrome," meaning it occurs alongside another autoimmune disorder. This overlapping nature raises questions about the connection between Sjögren’s and other autoimmune diseases, the implications for diagnosis and treatment, and how patients can best manage multiple conditions simultaneously.

Understanding Autoimmune Diseases

Autoimmune diseases occur when the immune system mistakenly attacks the body’s own tissues, recognizing them as foreign invaders. Instead of protecting the body, the immune system produces autoantibodies that cause chronic inflammation and damage. There are more than 80 recognized autoimmune conditions, including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), type 1 diabetes, multiple sclerosis, and autoimmune thyroid disease.

These diseases share common traits, such as:

  • Immune system dysregulation

  • Chronic inflammation

  • Fluctuating symptoms (flares and remissions)

  • Genetic predispositions

  • A higher prevalence in women

Sjögren’s syndrome fits within this category and often overlaps with others.

Primary vs. Secondary Sjögren’s Syndrome

  • Primary Sjögren’s syndrome occurs independently and is not associated with another autoimmune disease.

  • Secondary Sjögren’s syndrome occurs in people who already have another autoimmune condition.

The symptoms of both types are similar, but the presence of another autoimmune disorder can complicate diagnosis, treatment, and disease progression.

Common Autoimmune Diseases Associated with Sjögren’s

1. Rheumatoid Arthritis (RA)

RA is a chronic autoimmune disease that primarily affects the joints. It is one of the most common diseases associated with secondary Sjögren’s.

Shared symptoms and concerns:

  • Joint pain and stiffness

  • Fatigue

  • Increased risk of systemic inflammation

Patients with both RA and Sjögren’s may experience more severe joint damage and higher levels of fatigue.

2. Systemic Lupus Erythematosus (SLE)

Lupus is a systemic autoimmune disease that can affect the skin, joints, kidneys, brain, and other organs.

Shared features with Sjögren’s:

  • Presence of ANA (antinuclear antibodies)

  • Overlap in symptoms such as fatigue, joint pain, and mouth ulcers

  • Increased risk of organ involvement

Having both SLE and Sjögren’s may increase the complexity of treatment and monitoring.

3. Scleroderma (Systemic Sclerosis)

Scleroderma is an autoimmune condition that causes the skin and connective tissues to harden and tighten. It can also affect internal organs.

Overlap with Sjögren’s:

  • Dryness of eyes and mouth

  • Gastrointestinal problems

  • Lung involvement

This combination may lead to more pronounced vascular issues and digestive complications.

4. Autoimmune Thyroid Diseases

Conditions like Hashimoto's thyroiditis and Graves' disease frequently coexist with Sjögren’s.

Common links:

  • Hormonal imbalances

  • Fatigue and temperature sensitivity

  • Shared genetic markers (e.g., HLA-DR3)

Managing thyroid function is essential in these patients to prevent metabolic disturbances.

5. Autoimmune Hepatitis and Primary Biliary Cholangitis (PBC)

Both liver-related autoimmune diseases can occur with Sjögren’s and cause overlapping liver symptoms.

Important symptoms to monitor:

  • Elevated liver enzymes

  • Jaundice

  • Abdominal discomfort

Routine liver function tests can help detect early signs of liver involvement in patients with Sjögren’s.

6. Mixed Connective Tissue Disease (MCTD)

MCTD is a condition with features of multiple autoimmune diseases, including lupus, RA, and scleroderma.

Overlap with Sjögren’s:

  • Raynaud’s phenomenon

  • Joint inflammation

  • Fatigue and dryness

This mix often requires a coordinated approach to treatment.

Why Autoimmune Diseases Overlap

The reason for these overlaps is not entirely understood, but several contributing factors include:

  • Genetic susceptibility: Certain genes, such as HLA types, predispose individuals to multiple autoimmune conditions.

  • Shared environmental triggers: Infections, stress, or hormonal changes may trigger immune responses that affect multiple tissues.

  • Immune system pathways: Many autoimmune diseases involve similar immune mechanisms and inflammatory mediators.

  • Molecular mimicry: The immune system may attack self-tissues that resemble a foreign pathogen, leading to multiple conditions over time.

Because of these factors, a person with one autoimmune disease is at higher risk of developing another.

Challenges in Diagnosis

Diagnosing Sjögren’s in the presence of another autoimmune condition can be difficult because symptoms overlap. For example:

  • Dryness may be misattributed to medication side effects or other disease manifestations.

  • Fatigue and joint pain are nonspecific symptoms.

  • Lab markers like ANA or rheumatoid factor (RF) may be positive in multiple diseases.

A comprehensive diagnostic approach, including specific antibodies (anti-SSA/Ro, anti-SSB/La), salivary gland imaging, and biopsies, is often needed.

Managing Coexisting Autoimmune Conditions

Having more than one autoimmune disease requires a more tailored and coordinated care strategy. Here are some important management principles:

1. Collaborative Care

  • Work with a team that may include a rheumatologist, endocrinologist, gastroenterologist, and primary care physician.

2. Individualized Treatment Plans

  • Medications like corticosteroids, immunosuppressants, or biologics may need to be adjusted depending on which disease is more active.

3. Routine Monitoring

  • Regular blood tests and imaging to monitor organ function and inflammation levels.

4. Lifestyle Modifications

  • Adequate hydration, balanced nutrition, stress management, and regular exercise support immune health and energy levels.

5. Patient Education

  • Understanding the nature of each condition helps patients recognize flares, avoid triggers, and adhere to treatment.

Prognosis and Outlook

While having multiple autoimmune diseases may increase complexity, it does not mean a poor prognosis. Many patients lead active lives with proper medical support, regular monitoring, and self-care. Early detection and treatment of complications are critical in preserving function and quality of life.

The use of disease-modifying antirheumatic drugs (DMARDs), targeted biologics, and supportive therapies continues to improve outcomes.

Conclusion

Sjögren’s syndrome rarely stands alone. Its frequent association with other autoimmune diseases reflects the intricate nature of immune system dysfunction. Understanding these connections is essential for timely diagnosis, effective treatment, and proactive disease management. By working closely with healthcare professionals and staying informed, individuals with Sjögren’s and coexisting autoimmune conditions can better manage their health and maintain a fulfilling life despite the challenges.