Lyme Disease Without a Rash: Why the Bullseye Isn’t Required

Lyme disease without a rash is more common than many clinicians expect—and relying on the presence of a bullseye rash can lead to missed or delayed diagnosis.

This is one of the most common reasons Lyme disease is overlooked.

This is where expectations don’t match reality.

Many studies used to define Lyme disease required patients to meet strict surveillance criteria set by the <:contentReference[oaicite:0]{index=0}>.

These criteria often include an erythema migrans (EM) rash measuring at least 2 inches in diameter.

This is where the problem begins. Surveillance definitions are not designed for clinical diagnosis—but are often used that way.

Start here: Lyme disease symptoms guide

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How Common Is a Lyme Disease Rash?

Do most patients actually develop a rash?

Studies using strict criteria tend to report higher rates of rash.

However, when broader patient populations are studied, the incidence is significantly lower.

This is where the numbers change.

• In the original study describing Lyme disease in Lyme, Connecticut, only 25% of patients had an EM rash (Steere et al., 1977).
• In a National Institutes of Health study of Lyme encephalopathy, only 56% of patients had an EM rash—despite confirmed infection by IgG Western blot (Fallon et al., 2008).

These findings have been consistent across multiple studies of Lyme disease.

These findings suggest that many patients with Lyme disease never develop—or never notice—a rash.

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Why Does This Matter for Diagnosis?

This is where missed diagnoses occur.

If clinicians expect a rash to confirm Lyme disease, patients without one may be overlooked.

This is where one missing sign can delay care.

Early symptoms such as fatigue, headache, or joint pain may not immediately suggest Lyme disease—especially in the absence of a rash.

Learn more in our Lyme disease test accuracy guide.

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Can Relying on a Rash Lead to Underdiagnosis?

This is where broader impact becomes clear.

This is part of a broader pattern of missed and delayed Lyme disease diagnosis.

Overreliance on the EM rash may:

• Delay diagnosis in individual patients
• Lead to denial of treatment
• Underestimate the true incidence of Lyme disease

This is where surveillance definitions can conflict with clinical care.

Surveillance criteria are designed for tracking disease—not for ruling it out in individual patients.

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Clinical Takeaway

Lyme disease does not always present with a bullseye rash.

Absence of a rash does not exclude the diagnosis.

If symptoms suggest Lyme disease—but no rash appears—it’s worth asking why—again.

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Related Reading

• Single-dose prophylaxis may prevent a rash but not infection

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References

1. Shapiro, E. D., & Wormser, G. P. (2018). Controversies about Lyme disease—Reply. JAMA, 320(23), 2482–2483.
2. Gerber, M. A., Shapiro, E. D., Burke, G. S., Parcells, V. J., & Bell, G. L. (1996). Lyme disease in children in southeastern Connecticut. New England Journal of Medicine, 335(17), 1270–1274.
3. Sigal, L. H., Zahradnik, J. M., Lavin, P., et al. (1998). A vaccine consisting of recombinant Borrelia burgdorferi outer-surface protein A to prevent Lyme disease. New England Journal of Medicine, 339(4), 216–222.
4. Steere, A. C., Malawista, S. E., Snydman, D. R., et al. (1977). Lyme arthritis: An epidemic of oligoarticular arthritis in children and adults in three Connecticut communities. Arthritis & Rheumatism, 20(1), 7–17.
5. Fallon, B. A., Keilp, J. G., Corbera, K. M., et al. (2008). A randomized, placebo-controlled trial of repeated IV antibiotic therapy for Lyme encephalopathy. Neurology, 70(13), 992–1003.

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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