Lyme Disease and ME/CFS (Chronic Fatigue Syndrome)

Quick answer

ME/CFS (myalgic encephalomyelitis/chronic fatigue syndrome) is a serious, long-lasting illness marked by a crash in symptoms after activity, called post-exertional malaise. CDC says infections may trigger it in some people. Lingering symptoms after Lyme disease can look similar, and CDC points people with those symptoms to ME/CFS management strategies such as careful pacing.

What ME/CFS is

ME/CFS keeps many people from doing their usual activities, and about 1 in 4 people with it are confined to bed at some point, according to CDC. It can affect anyone, at any age, though it is most common in middle age and in women. CDC estimates that more than 9 in 10 people with ME/CFS have not been diagnosed.

Main symptoms include:

• Severe fatigue that is not much relieved by rest
• Symptoms that get worse after physical or mental effort
• Sleep that does not leave you refreshed
• Problems with thinking and memory
• Dizziness or feeling worse when upright
• Pain

The IOM report noted that the name “chronic fatigue syndrome” can trivialize the illness, and proposed the name systemic exertion intolerance disease (SEID). CDC still uses the name ME/CFS.

Post-exertional malaise: the hallmark

Post-exertional malaise (PEM) is a worsening of symptoms after even minor physical, mental or emotional effort that a person could handle before getting sick. CDC says PEM symptoms typically show up 12 to 48 hours after activity and can last days or weeks. That delay is why people often overdo it on a good day and do not connect the crash to the activity until later.

PEM is what separates ME/CFS from ordinary tiredness. If you notice a pattern of crashing after effort, tell your clinician and keep a simple diary of activity and symptoms.

How ME/CFS is diagnosed (NASEM 2015 criteria)

There is no single lab test. CDC shares the 2015 IOM (NASEM) criteria, which require all three of these:

1. A substantial drop in activity compared with before the illness, lasting more than 6 months, with fatigue that is new, often severe, not caused by ongoing unusual exertion and not much relieved by rest.
2. Post-exertional malaise.
3. Unrefreshing sleep.

Plus at least one of these:

• Cognitive impairment (problems with thinking, memory or processing information)
• Orthostatic intolerance (symptoms worse when upright and better when lying down)

The symptoms should be present at least half the time at moderate or greater intensity. The IOM report says a thorough history, physical exam and targeted testing are necessary and often sufficient. Clinicians also look for other illnesses with similar symptoms, which is where a history of tick bites or Lyme disease belongs in the conversation.

Infections as triggers

CDC says the cause of ME/CFS is unknown and may involve more than one factor. Because many people say their illness began with a flu-like illness, researchers suspect infections may trigger it in some people. CDC notes that about 1 in 10 people infected with Epstein-Barr virus, Ross River virus or Coxiella burnetii (the bacterium behind Q fever) later develop an illness that looks like ME/CFS. People have also reported ME/CFS-like illness after COVID-19, known as long COVID.

CDC’s ME/CFS pages do not list Lyme disease as a known trigger. However, a 2022 review in Nature Medicine (Choutka and colleagues) grouped post-treatment Lyme disease syndrome with other unexplained post-infection syndromes that share features such as exertion intolerance, fatigue, unrefreshing sleep and brain fog. The review called the underlying mechanisms poorly understood.

Overlap with PTLDS and long COVID

CDC says most people recover fully after Lyme treatment, but some have prolonged fatigue, body aches or difficulty thinking. CDC calls this post-treatment Lyme disease syndrome (PTLDS) and says its cause is unknown. It notes similar symptoms have been reported after other infections, including COVID-19.

Some people with lingering Lyme symptoms meet the ME/CFS criteria and some do not. Either way, a clinician who knows ME/CFS can help. The patient-advocate view on long-term symptoms is covered in our chronic Lyme guide.

Pacing and managing symptoms

CDC says there is no cure or approved treatment for ME/CFS, but symptoms can be managed. Its guidance centers on pacing: balancing rest and activity to avoid crashes.

• Find your energy envelope. Learn your physical and mental limits and try to stay within them. An activity and symptom diary helps.
• Avoid push-and-crash cycles. Doing too much on a good day often leads to a relapse.
• Make tasks smaller. CDC suggests sitting for tasks such as showering or laundry, taking frequent breaks, and breaking big jobs into steps.
• Be careful with exercise. CDC says people with ME/CFS cannot tolerate vigorous aerobic exercise and that standard exercise advice for healthy people can cause harm. Any activity plan should be individualized and increased only cautiously.
• Treat the worst symptom first. CDC suggests patients and clinicians choose the most disruptive symptom, such as sleep problems, pain or dizziness, and address it first.

For practical energy tips, see our Lyme disease fatigue guide and working with Lyme disease. For the bigger picture of living with ongoing symptoms, see Step 6 of How to beat Lyme.

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