Can You Have Lyme Disease Without a Rash? How Common Is It?
Lyme disease may occur without a rash.
Studies report different erythema migrans rates.
Diagnosis requires more than a rash.
Can you have Lyme disease without a rash? Yes. Many people diagnosed with Lyme disease never develop, recognize, or recall an erythema migrans (EM) rash. Although the classic “bull’s-eye” rash is one of the best-known signs of Lyme disease, studies have reported widely different rates of erythema migrans depending on how patients were selected.
Understanding why these differences occur is important. Physicians who expect every patient with Lyme disease to have an erythema migrans rash may delay diagnosis in patients who present with flu-like symptoms, neurologic problems, arthritis, or cardiac manifestations without a recognized rash.
It is also important to distinguish between the CDC surveillance case definition and clinical diagnosis. The CDC surveillance case definition was developed primarily for standardized public health surveillance and research rather than to serve as a standalone clinical diagnostic tool for individual patients. As a result, studies using surveillance criteria may report different erythema migrans rates than studies evaluating patients in routine clinical practice.
One reason the reported frequency of erythema migrans varies is that many published studies enrolled participants using the CDC surveillance case definition. This approach tends to identify patients who meet specific reporting criteria and may not fully represent the broader population of individuals diagnosed with Lyme disease in clinical practice.
Why do studies report different rates of erythema migrans?
Reported rates of erythema migrans vary considerably because researchers often study different patient populations. Studies requiring participants to meet the CDC surveillance case definition are more likely to enroll patients with a qualifying erythema migrans rash, resulting in higher reported percentages than studies evaluating all patients with confirmed Lyme disease.
For example, two influential studies published in 1996 and 1998 reported that most participants had erythema migrans. These findings are frequently cited as evidence that the rash occurs in the majority of patients.
The 1996 study by Gerber and colleagues evaluated children with Lyme disease in southeastern Connecticut. The 1998 study by Sigal and colleagues assessed participants enrolled in a Lyme disease vaccine trial. Both studies contributed important information regarding Lyme disease, but both also relied on enrollment criteria based on the CDC surveillance case definition.
Because the surveillance definition requires a qualifying erythema migrans rash or another accepted clinical manifestation, these studies are not necessarily representative of every patient diagnosed with Lyme disease in routine clinical practice.
CDC surveillance criteria can influence reported rash rates
The CDC surveillance case definition was created to improve consistency in disease reporting across the United States. It is valuable for epidemiologic surveillance, but it was not intended to establish or exclude the diagnosis of Lyme disease in an individual patient.
When investigators enroll only patients who satisfy surveillance criteria, the proportion of participants with erythema migrans may appear higher than it would in a broader clinical population. This difference helps explain why published estimates of erythema migrans frequency vary considerably among studies.
Studies evaluating broader groups of patients—including those diagnosed clinically or those presenting later in the course of illness—often report substantially lower rates of erythema migrans.
Can Lyme disease occur without an erythema migrans rash?
Yes. Studies that include all patients with Lyme disease—not just those meeting the CDC surveillance case definition—have consistently reported lower rates of erythema migrans. These findings suggest that many patients either never develop a recognized rash or do not recall seeing one.
Both studies, published in 1996 and 1998, required that participants meet the Centers for Disease Control and Prevention (CDC) surveillance case definition for Lyme disease. This surveillance definition requires an erythema migrans rash measuring at least 5 cm (approximately 2 inches) in diameter or another qualifying manifestation of Lyme disease.
By contrast, studies designed to include broader groups of patients have reported substantially lower percentages of erythema migrans. For example, only 25% of patients had an erythema migrans rash in the original study describing Lyme disease in Lyme, Connecticut. [4]
Likewise, in a National Institutes of Health (NIH)-sponsored study of Lyme encephalopathy, only 56% of patients recalled having an erythema migrans rash, even though every participant had laboratory confirmation of Lyme disease with a positive IgG Western blot. [5]
These findings illustrate why estimates of erythema migrans frequency vary widely across the medical literature. Differences in study design, patient selection, disease stage, and patient recall all influence the reported percentage of patients with a rash.
Why does this matter for patients?
Many people search online asking, “Can you have Lyme disease without a rash?” The answer is important because an overreliance on erythema migrans may delay diagnosis in patients who present with other manifestations of Lyme disease.
Patients may instead develop fever, fatigue, headache, muscle aches, joint pain, facial palsy, meningitis, heart block, or later neurologic symptoms without recalling a tick bite or a characteristic rash. Clinical evaluation should consider the patient’s symptoms, exposure history, physical examination, and appropriate laboratory testing rather than relying on a rash alone.
Recognizing that Lyme disease can occur without an erythema migrans rash may improve timely diagnosis and treatment while reducing the risk that cases are overlooked.
For patients, the key message is that the absence of a rash should not automatically lower suspicion for Lyme disease. Physicians should interpret the entire clinical picture, including compatible symptoms, possible tick exposure, physical findings, and laboratory results when appropriate. Early recognition remains important because prompt treatment is associated with better outcomes.
Frequently Asked Questions
Can you have Lyme disease without a rash?
Yes. Many patients diagnosed with Lyme disease never develop, notice, or remember an erythema migrans rash. Reported percentages vary because some studies enrolled patients using CDC surveillance criteria, while others evaluated broader clinical populations.
How common is Lyme disease without a rash?
There is no single percentage. The reported frequency depends on the population being studied and the enrollment criteria used. The original Lyme, Connecticut study reported erythema migrans in only 25% of patients, while an NIH-sponsored Lyme encephalopathy study found that 56% of patients recalled a rash despite laboratory confirmation of Lyme disease. Studies using CDC surveillance enrollment criteria have reported substantially higher percentages.
Does the absence of a bull’s-eye rash rule out Lyme disease?
No. Although an erythema migrans rash is an important diagnostic finding when present, its absence does not exclude Lyme disease. Physicians should consider a patient’s symptoms, possible tick exposure, physical examination, and appropriate laboratory testing when evaluating suspected Lyme disease.
Clinical Takeaway
Many patients with Lyme disease do not develop or recognize an erythema migrans rash. Differences in study design, enrollment criteria, disease stage, and patient selection help explain why published estimates of rash frequency vary considerably.
Clinicians should recognize that the CDC surveillance case definition was developed for public health surveillance rather than as a standalone clinical diagnostic tool. Patients with compatible symptoms and tick exposure may still have Lyme disease even when a characteristic rash is absent.
The absence of an erythema migrans rash should not, by itself, exclude the diagnosis of Lyme disease.
Related Articles
Lyme Disease Symptoms Guide
Lyme Disease Misdiagnosis
Why Early Lyme Disease Tests Can Be Negative
Single-Dose Prophylactic Treatment After a Tick Bite Only Prevents a Lyme Rash
References:
- Shapiro ED, Wormser GP. Controversies About Lyme Disease—Reply. JAMA. 2018;320(23):2482-2483.
- Gerber MA, Shapiro ED, Burke GS, Parcells VJ, Bell GL. Lyme disease in children in southeastern Connecticut. Pediatric Lyme Disease Study Group. N Engl J Med. 1996;335(17):1270-1274.
- Sigal LH, Zahradnik JM, Lavin P, et al. A vaccine consisting of recombinant Borrelia burgdorferi outer-surface protein A to prevent Lyme disease. Recombinant Outer-Surface Protein A Lyme Disease Vaccine Study Consortium. N Engl J Med. 1998;339(4):216-222.
- Steere AC, Malawista SE, Snydman DR, et al. Lyme arthritis: an epidemic of oligoarticular arthritis in children and adults in three Connecticut communities. Arthritis Rheum. 1977;20(1):7-17.
- Fallon BA, Keilp JG, Corbera KM, et al. A randomized, placebo-controlled trial of repeated IV antibiotic therapy for Lyme encephalopathy. Neurology. 2008;70(13):992-1003.
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
Thank you Dr. Cameron for that information.