Fibromyalgia vs Lyme Disease: Could Your Diagnosis Be Wrong?

Fibromyalgia vs Lyme disease is one of the most common—and important—diagnostic challenges. Both conditions share symptoms like pain, fatigue, and brain fog, making it easy to miss an underlying infection.

Many patients are told they have fibromyalgia—but continue to struggle despite treatment.

This raises a critical question:

Could some cases of fibromyalgia actually represent undiagnosed Lyme disease or co-infections?

For more on this pattern, see Lyme disease misdiagnosis.

Symptom Overlap Between Fibromyalgia and Lyme Disease

Fibromyalgia and Lyme disease share many symptoms, including:

• Widespread muscle pain
• Fatigue
• Sleep disturbances
• Gastrointestinal symptoms
• Difficulty concentrating (brain fog)
• Headaches
• Sensitivity to light, sound, or temperature

This overlap can lead to delayed or missed diagnosis.

For a broader view of symptom patterns, see Lyme disease symptoms guide.

Why Fibromyalgia Treatments Often Fall Short

Standard treatments for fibromyalgia do not always lead to full recovery.

• Duloxetine (Cymbalta): ~30% more effective than placebo
• Milnacipran (Savella): ~50% more effective than placebo
• Pregabalin (Lyrica): helps some patients, but many remain symptomatic

When symptoms persist, alternative explanations—including infection—should be considered.

Diagnostic Challenges

It can be difficult to rule out Lyme disease in patients diagnosed with fibromyalgia.

Symptoms such as fatigue, insomnia, and chronic pain are common to both conditions.

Even physical findings may overlap, including:

• Synovitis
• Bursitis
• Sacroiliitis

Limitations in Lyme disease testing further complicate diagnosis.

Learn more about why Lyme tests can be negative.

Evidence of Overlap

Research suggests a meaningful overlap between fibromyalgia and Lyme disease:

• 15% of chronic neurologic Lyme patients also met fibromyalgia criteria
• 12% of Lyme patients in a rheumatology clinic had fibromyalgia
• 44% of fibromyalgia patients had abnormal spinal fluid findings, including evidence of Borrelia burgdorferi

These findings suggest that some cases may be overlapping—or misclassified.

Clinical Takeaway

Fibromyalgia and Lyme disease can look very similar—but they are not the same condition.

• Persistent symptoms warrant further evaluation
• Exposure history and symptom patterns matter
• Underlying infection should be considered when treatment fails

Keeping a broad differential diagnosis may help avoid missed opportunities for treatment.

For next steps, visit recovery from Lyme disease.

Frequently Asked Questions

Can Lyme disease be misdiagnosed as fibromyalgia?
Yes. The symptom overlap can lead to diagnostic confusion.

Can someone have both?
Yes. Some patients meet criteria for both conditions.

When should Lyme disease be considered?
When symptoms persist despite treatment or exposure risk is present.

Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.

Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention