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Harvard Health Publishing, Harvard Medical School

Persistent Symptoms of Lyme Disease

Learn about the theories that may explain why some people continue to experience symptoms associated with Lyme disease.

When Lyme disease symptoms persist

A tired woman resting on a couch.
Lyme symptoms can be persistent and debilitating.
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Some people who are diagnosed with Lyme disease and treated—at any stage—continue to experience troublesome symptoms. Most often, these go away within six to 12 months but may last more than a year. Specific persistent symptoms and their severity can vary. Some people have mild lingering symptoms, whereas others have debilitating symptoms that make it hard to get through the day, let alone take part in enjoyable activities.

You may have heard various terms for persistent symptoms, such as post-treatment Lyme disease (PTLD), post-treatment Lyme disease syndrome (PTLDS), long Lyme, or chronic Lyme. PTLD is a research term used to define the 10% to 20% of people who continue to experience symptoms after completing antibiotic treatment for Lyme disease. Those people meet the following criteria:

  • a prior documented episode of Lyme disease meeting CDC criteria in which all objective signs resolve

  • fatigue, widespread musculoskeletal pain, and/or cognitive difficulties which begin within six months, last for at least six months, and are significant enough to impair daily function

  • the absence of specific co-morbid or pre-existing conditions which should otherwise explain symptoms.

Some doctors use the terms PTLD or PTLDS. Some use one of the other terms to more broadly include other sufferers, such as those who are still undergoing treatment or those who do not meet the CDC diagnostic criteria but have been clinically diagnosed with Lyme (for more information on diagnostic criteria, see Diagnosis & Testing).

“I was assured many times in the first few months by doctors that my symptoms would resolve soon. Symptoms still continue and are disabling.”

Lyme Disease Patient Experience Survey Respondent

Male, 52, East Providence, RI

Possible causes of persistent symptoms

Regardless of terminology, persistent symptoms of Lyme disease are real and well documented. However, the cause (or causes) are poorly understood. Current theories include:

Immune system dysregulation: The body’s response to fighting infection runs amok and persists long after it is helpful. This may be due to lingering spirochete (Lyme disease bacteria) proteins, persistent inflammation, or other autoimmune issues.

Damage to nerve pathways: Lyme disease is well known to affect the nervous system. Nerve damage may contribute to continued Lyme-related symptoms.

Lingering infection: It is possible there may be active infection that is hard to detect. Limited case studies, and studies in animal models, have shown evidence of persistent spirochetes, but there is not yet definitive evidence of persistent Lyme disease infection in humans. More research is needed.

“My symptoms ebb and flow so one symptom is bad one month while the others are mild, then the next month something else takes over.”

Lyme Disease Patient Experience Survey Respondent

Female, 51, Conneautville, PA

Laboratory research being conducted by a female scientist looking through a microscope.
Additional research is needed to understand the cause or causes of persistent Lyme disease symptoms.
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Persistent symptoms associated with Lyme disease

People have reported symptoms that affect the eyes, liver, kidneys, bladder, lungs, heart, blood vessels, reproductive organs, and the neurologic and lymphatic systems. The most common symptoms are:

• fatigue

• muscle aches

• joint pain and stiffness

• headaches

• problems with thinking, concentration, and memory, often described as “brain fog”

• anxiety or depression

• weakness

• numbness or tingling in the extremities.

  • Post-treatment Lyme Disease as a Model for Persistent Symptoms in Lyme Disease. Frontiers in Medicine, 2020.
  • Prevalence and Correlates of Long COVID Symptoms Among US Adults. JAMA Network Open, 2022.
  • Recent progress in Lyme disease and remaining challenges. Frontiers in Medicine, 2021.
  • U.S. Census Bureau, Household Pulse Survey, 2022-2023. Long COVID. National Center for Health Statistics. Generated interactively.