Can Lyme Disease Kill You? What the Evidence Shows
Lyme disease is usually a treatable infection, especially when recognized early. However, in rare cases, serious complications can become life-threatening if diagnosis and treatment are delayed.
Understanding these complications may help patients and clinicians recognize warning signs before severe cardiac, neurologic, or systemic illness develops.
Lyme Disease Is Usually Not Fatal
In most cases, Lyme disease is not deadly, particularly when diagnosed and treated early.
Borrelia burgdorferi, the bacterium that causes Lyme disease, typically responds well to antibiotics such as doxycycline or amoxicillin.
However, untreated infection may spread and affect the heart, nervous system, or other organ systems. Although uncommon, these complications can become dangerous in rare situations.
1. Lyme Carditis
Lyme disease may affect the heart’s electrical conduction system, causing Lyme carditis.
Inflammation involving the conduction pathways can lead to dangerous rhythm abnormalities, including varying degrees of heart block.
In 2013, the CDC investigated several cases of sudden cardiac death associated with undiagnosed Lyme carditis, including three young adults.
Symptoms may include:
- Chest pain
- Shortness of breath
- Palpitations
- Lightheadedness or fainting
For more information, see Patients can die when Lyme carditis is not treated.
2. Neurologic Lyme Disease
In some patients, Lyme disease affects the nervous system, leading to neurologic Lyme disease or neuroborreliosis.
Complications may include meningitis, radiculopathy, encephalitis, neuropathy, cognitive dysfunction, or autonomic symptoms.
While severe neurologic complications are uncommon, delayed diagnosis may increase the risk of progressive neurologic involvement.
For a broader overview, see Lyme disease symptoms.
3. Babesia Co-infection
The ticks that transmit Lyme disease may also carry Babesia, a malaria-like parasite that infects red blood cells.
Babesiosis may cause severe anemia, respiratory distress, organ failure, or life-threatening illness in vulnerable individuals.
According to the CDC, severe babesiosis occurs most often in:
- Older adults
- Immunocompromised individuals
- Patients without a spleen
Transfusion-associated Babesia infections have also resulted in fatal cases.
4. Other Serious Complications
Other uncommon but potentially serious complications may include:
- Autonomic dysfunction causing severe blood pressure instability
- Neuropsychiatric symptoms contributing to impaired functioning or suicidal ideation
- Severe inflammatory reactions in advanced disease
- Profound weight loss or malnutrition in prolonged undiagnosed illness
How Often Does Lyme Disease Cause Death?
Deaths directly related to Lyme disease remain rare but documented.
- Between 1985 and 2013, nine deaths in the United States were linked directly to Lyme disease or associated complications.
- The most documented fatal complication is Lyme carditis.
Many reported deaths involved previously healthy individuals whose cardiac complications were never recognized before collapse.
Early Recognition Matters
Early diagnosis and treatment remain the most important ways to prevent serious complications.
However, diagnosis may be delayed when symptoms are mistaken for viral illness, anxiety, stress, cardiac disease, neurologic disease, or other conditions.
Patients with unexplained cardiac symptoms, neurologic symptoms, severe fatigue, syncope, or fluctuating systemic illness — particularly in Lyme-endemic areas — may warrant evaluation for Lyme disease and possible co-infections.
Clinical Takeaway
Serious complications of Lyme disease are uncommon but may involve Lyme carditis, neurologic Lyme disease, or Babesia co-infection when diagnosis and treatment are delayed.
Most patients recover fully with prompt treatment. When cardiac symptoms, fainting, neurologic dysfunction, or severe systemic illness occur in Lyme-endemic areas, evaluation for Lyme disease and associated co-infections is warranted.
Frequently Asked Questions
Can Lyme disease be fatal?
Yes, in rare cases. The most documented fatal complication is Lyme carditis, which can cause dangerous heart rhythm abnormalities when undiagnosed and untreated.
How many people have died from Lyme disease?
Between 1985 and 2013, nine deaths in the United States were directly linked to Lyme disease or its complications. Most involved undiagnosed Lyme carditis in previously healthy individuals.
Can Babesia kill you?
Yes. Severe babesiosis can cause life-threatening anemia, respiratory distress, and organ failure — particularly in older adults, immunocompromised patients, and those without a spleen.
What are the warning signs of dangerous Lyme disease complications?
Warning signs include chest pain, fainting, shortness of breath, palpitations, severe fatigue, or neurologic symptoms — particularly in Lyme-endemic areas. These warrant prompt medical evaluation.
Related Articles
- Patients Can Die When Lyme Carditis Is Not Treated
- Lyme Carditis Symptoms
- Babesia and Lyme Disease
- Lyme Disease Misdiagnosis
References
- CDC. Sudden Cardiac Deaths Associated With Lyme Carditis. MMWR Morb Mortal Wkly Rep. 2013;62(49):993-996.
- Robinson ML, Kobayashi T, Higgins Y, Calkins H, Melia MT. Lyme carditis. Infect Dis Clin North Am. 2015;29(2):255-268.
- Yeung C, Baranchuk A. Diagnosis and Treatment of Lyme Carditis: JACC Review Topic of the Week. J Am Coll Cardiol. 2019;73(6):717-726.
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
