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Lyme Disease vs Bell’s Palsy: When Facial Paralysis Is Misdiagnosed
Lyme disease can cause sudden facial paralysis
Bell’s palsy is technically a diagnosis of exclusion
Recognizing the difference can change treatment
Lyme disease vs Bell’s palsy can be difficult to distinguish when a patient first develops sudden facial weakness. Both can produce peripheral facial nerve palsy, causing drooping of one side of the face, difficulty closing the eye, an asymmetric smile, and other facial symptoms.
But there is an important difference. Bell’s palsy is technically an idiopathic facial nerve palsy, meaning that no specific cause has been identified. Lyme disease, on the other hand, is a recognized infectious cause of peripheral facial nerve palsy.
A 2025 review of Bell’s palsy emphasized that the condition remains a diagnosis of exclusion and warned that clinicians may mistakenly apply the Bell’s palsy label when an underlying cause such as Lyme disease or Ramsay-Hunt syndrome is present.1
This distinction matters because treatment depends on the underlying cause. Corticosteroids are commonly used for idiopathic Bell’s palsy, while Lyme-associated facial palsy requires antibiotic treatment directed at Lyme disease.
Bell’s palsy is not the same as facial palsy
The terms Bell’s palsy and facial palsy are often used interchangeably, but they do not technically mean the same thing.
Peripheral facial nerve palsy describes weakness or paralysis resulting from dysfunction of the facial nerve, also known as the seventh cranial nerve. Many conditions can produce peripheral facial palsy, including infections, trauma, tumors, autoimmune disorders, and other neurologic conditions.1
Bell’s palsy refers specifically to an acute peripheral facial nerve palsy for which another cause has not been identified. Gardner and colleagues emphasized in their 2025 review that Bell’s palsy remains a diagnosis of exclusion.1
Therefore, when Borrelia burgdorferi infection is identified as the cause of facial weakness, the more accurate diagnosis is Lyme-associated facial palsy or Lyme neuroborreliosis with facial nerve involvement, rather than idiopathic Bell’s palsy.
Why Lyme disease can be mistaken for Bell’s palsy
Lyme-associated facial palsy and idiopathic Bell’s palsy may look remarkably similar when facial weakness first appears.
Patients may develop:
- Drooping of one side of the face
- Difficulty closing one eye
- Flattening of the nasolabial fold
- Difficulty smiling
- Altered taste
- Ear or facial discomfort
- Changes in tearing
The appearance of the facial weakness alone may therefore be insufficient to identify the cause.
The 2025 Gardner review specifically cautions against assuming that every peripheral facial palsy represents idiopathic Bell’s palsy when an underlying disorder such as Lyme disease may be responsible.1
What clues suggest Lyme disease?
Several clinical and epidemiologic clues can raise suspicion for Lyme disease in a patient presenting with facial paralysis.
These include:
- Living in or traveling to a Lyme-endemic area
- Outdoor or tick exposure
- Presentation during tick season
- Fever or a recent flu-like illness
- Headache or neck stiffness
- Muscle or joint pain
- Radicular or shooting nerve pain
- Erythema migrans or multiple skin lesions
- Other neurologic symptoms
However, the absence of a known tick bite or recognizable erythema migrans rash does not exclude Lyme disease.
In a 2022 pediatric study of 306 children with acute peripheral facial palsy in a Lyme-endemic region, 82 children had Lyme-related facial palsy. Children with Lyme facial palsy were much more likely than those with Bell’s palsy to have a preceding systemic illness with symptoms such as fever, malaise, headache, muscle aches, or joint pain. Most Lyme-related cases also presented between June and November.2
Bilateral facial palsy deserves particular attention
Idiopathic Bell’s palsy is usually unilateral. Facial weakness involving both sides is uncommon and should broaden the differential diagnosis.
The Gardner review notes that bilateral facial nerve palsy is more often associated with an underlying systemic disorder and warrants a more extensive evaluation.1
Lyme neuroborreliosis is one of the conditions that can produce bilateral facial nerve palsy.
This does not mean that bilateral facial palsy proves Lyme disease. Other infectious, inflammatory, neurologic, and systemic disorders can produce the same finding. But bilateral involvement makes it particularly important not to automatically label the presentation idiopathic Bell’s palsy.
Young woman diagnosed with Bell’s palsy later found to have Lyme disease
A published case from India illustrates how Lyme-associated facial palsy can initially be diagnosed as Bell’s palsy.3
A young woman developed facial weakness during the final months of pregnancy. She had deviation of the mouth, decreased taste, and difficulty closing her eyes, blowing, and whistling.
She was diagnosed with right-sided Bell’s palsy and treated with prednisolone and methylcobalamin.
Two months later, she developed a much more extensive neurologic illness. Her symptoms included fever followed by rapidly progressive weakness of all four limbs and severe radiating pain involving the neck, back, arms, and legs.3
Further evaluation found asymmetric bilateral lower motor neuron facial weakness. Lyme testing was positive by ELISA and PCR.
The authors concluded that her earlier facial palsy had been misdiagnosed as Bell’s palsy, delaying recognition of Lyme neuroborreliosis.3
Lyme disease can occur without a recognized rash
One reason Lyme-associated facial palsy can be missed is that patients do not necessarily present with the classic history clinicians expect.
Some patients do not recall a tick bite. Others do not recognize an erythema migrans rash, and facial nerve palsy may sometimes be one of the first manifestations that brings the patient to medical attention.
Huston described a patient presenting with new-onset facial palsy who was ultimately recognized as having early disseminated Lyme disease after additional history revealed frequent hiking and examination identified multiple skin lesions consistent with erythema migrans.4
The case illustrates why exposure history and examination for other manifestations of Lyme disease can be important when evaluating sudden peripheral facial weakness.
Another Lyme patient progressed from unilateral to bilateral facial palsy
A 2025 case report provides another example of Lyme neuroborreliosis presenting through facial nerve involvement.5
The 47-year-old man initially developed unilateral facial nerve palsy that progressed to bilateral facial weakness. After additional investigation, he was diagnosed with Lyme neuroborreliosis and treated with intravenous ceftriaxone.
His facial weakness gradually improved during follow-up.5
The case reinforces an important point: facial palsy describes a neurologic finding, not necessarily the underlying diagnosis. When the presentation is atypical or additional symptoms develop, clinicians may need to look beyond idiopathic Bell’s palsy.
Why the distinction can change treatment
The difference between Bell’s palsy and Lyme-associated facial palsy is not merely terminology.
For idiopathic Bell’s palsy, corticosteroids started early are a standard treatment, and antiviral medication may sometimes be considered.1
When facial nerve palsy is caused by Lyme disease, antibiotic treatment directed at Borrelia burgdorferi is required.
The role of corticosteroids in Lyme-associated facial palsy remains less certain. In the 2022 pediatric cohort, early corticosteroid use was not associated with the investigators’ measure of ultimate facial recovery, although the study could not adequately assess subtle residual abnormalities or differences in time to recovery.2
The practical issue is therefore not that every patient with facial palsy should be assumed to have Lyme disease. Rather, Lyme disease should be considered when the clinical presentation and exposure history make it plausible before the facial weakness is classified as idiopathic Bell’s palsy.
Frequently Asked Questions
Can Lyme disease cause Bell’s palsy?
Lyme disease can cause peripheral facial nerve palsy that may initially be called Bell’s palsy. Technically, Bell’s palsy refers to idiopathic facial nerve paralysis. Once Lyme disease is identified as the cause, Lyme-associated facial palsy or Lyme neuroborreliosis with facial nerve involvement is more accurate terminology.
How can you tell Bell’s palsy from Lyme facial palsy?
The facial weakness itself may look very similar. Lyme disease becomes more likely when facial palsy occurs during tick season, after possible tick exposure, or together with fever, headache, neck pain, muscle or joint pain, radicular pain, erythema migrans, or other neurologic symptoms. Bilateral facial weakness also warrants evaluation for an underlying systemic cause.
Can Lyme disease cause facial paralysis without a rash?
Yes. Lyme-associated facial palsy can occur without a recognized erythema migrans rash. A patient may also have no memory of a tick bite.
Can Lyme disease cause facial paralysis on both sides?
Yes. Lyme neuroborreliosis can cause bilateral facial nerve palsy. Bilateral facial paralysis is uncommon and can have several causes, so it warrants evaluation for an underlying systemic disorder rather than automatically being labeled Bell’s palsy.
Does Lyme facial palsy require antibiotics?
Yes. When facial nerve palsy is caused by Lyme disease, antibiotic therapy directed at Lyme disease is required. This is one reason distinguishing Lyme-associated facial palsy from idiopathic Bell’s palsy is clinically important.
Clinical Takeaway
Sudden peripheral facial paralysis is often described as Bell’s palsy, but Bell’s palsy is technically an idiopathic diagnosis made after other causes have been considered.
Lyme disease is an important infectious cause of facial nerve palsy, particularly in patients with relevant geographic or outdoor exposure, presentation during tick season, systemic symptoms, radicular pain, rash, or other neurologic findings.
The key distinction is simple: Bell’s palsy has no identified cause. When Lyme disease is responsible for the facial paralysis, the diagnosis is Lyme-associated facial palsy—and that distinction can change treatment.
Related Articles
These related articles explore facial nerve palsy and neurologic Lyme disease.
Can Lyme Disease Cause Bell’s Palsy? Pediatric Study Finds 29% Had Lyme
Lyme Disease Facial Palsy: A Case of Treatment Failure
Bell’s Palsy From Lyme Disease: Nonflaccid Facial Palsy
Neurologic Lyme Disease Symptoms: How Lyme Affects the Nervous System
Lyme Disease Symptoms: Why They Come and Go
References
- Gardner S, Garber L, Grossi J. Bell’s Palsy: Description, Diagnosis, and Current Management. Cureus. 2025;17(1):e77656. doi:10.7759/cureus.77656. PMID:39974265.
- Guez-Barber D, Swami SK, Harrison JB, McGuire JL. Differentiating Bell’s Palsy From Lyme-Related Facial Palsy. Pediatrics. 2022;149(6):e2021053992. doi:10.1542/peds.2021-053992. PMID:35586981.
- Kayal N, Ghosh R, Mazumdar PS, Das S, Ghosh S, Pandit A, Benito-León J. Bilateral Facial Nerve Palsy in a Young Woman From West Bengal: Do Not Forget Lyme Neuroborreliosis. Neurol India. 2021;69(4):997-1001. doi:10.4103/0028-3886.325335. PMID:34507428.
- Huston P. New-onset Bell palsy and Lyme disease. Can Fam Physician. 2017;63(12):941. PMID:29237635.
- Mon T, Nyein A, Oo A. Infectious Mimics of Bell’s Palsy: Facial Nerve Palsy Due to Lyme Neuroborreliosis. Cureus. 2025;17(9):e93122. doi:10.7759/cureus.93122. PMID:41141012.
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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
