Lyme Disease Could Be The Cause Of Your Brain Fog and Fatigue

Lyme disease is a condition that occurs when you are bit by a tick. In some cases, people with Lyme disease can experience heavy brain fog and exhaustion.

If you regularly hike or enjoy walking along nature trails during the summer, you may be familiar with the black-legged tick notable for causing Lyme disease. According to the Centers for Disease Control and Prevention, approximately 476,000 diagnosed cases of Lyme disease occur each year—and that number is on the rise. 

Ticks transmit Lyme disease to humans through tick bites. Lyme disease typically produces short-term flu-like symptoms ranging from fever and chills to muscle pain. However, Lyme disease can also cause long-term symptoms that can last after the infection resolves, such as brain fog. 

woman sitting on bed holding her head in pain

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What Is Lyme Disease?

Lyme disease, the most common tick-borne illness in the U.S, is a bacterial infection typically caused by a group of bacteria called Borrelia burgdorferi (B. burgdorferi), and, less commonly, Borrelia mayonii (B. mayonii).

These black-legged ticks pick up harmful bacteria by feeding on the blood of mice and deer, and  then spread those bacteria to humans. Normally, ticks will attach to your skin and can be found on body parts such as the armpits or scalp. Once the tick has attached to your skin, the bacteria can infect your body. 

In order for you to become infected with Lyme disease, a tick has to be attached to you for at least 36 to 48 hours. However, black-legged ticks are often so small (one-eighth of an inch) that they are difficult to find. Unfortunately, you may not even be aware that a tick is on your skin until initial symptoms appear.

The Connection Between Brain Fog and Lyme Disease

If a tick bites you, common symptoms such as fatigue, fever and chills, headache, and muscle pain can occur. A skin rash may also develop and become larger over time. Left untreated, the disease may worsen and affect the heart, joints, and central nervous system. Lyme disease can also cause the blood vessels in the brain to become inflamed, leading some people to experience brain fog.

Brain fog is not a condition, but a symptom that can lead to:

  • Slow or sluggish thinking
  • Drowsiness 
  • Disorientation
  • Short-term memory loss 

Brain fog is different than general fatigue or forgetfulness. Most researchers think that brain fog is a form of mild cognitive impairment that can cause long-term feelings of exhaustion and decreased focus. Typically, physical fatigue may go away on its own if you get enough rest. This is not the case with brain fog.

In most cases of Lyme disease, brain fog appears due to a condition called post-treatment Lyme disease syndrome (PTLDS), which is estimated to occur in five to ten percent of people with Lyme disease. Symptoms of PTLDS can affect someone for more than six months after they complete antibiotic treatment. While brain fog can be a temporary symptom of PTLDS, some people report long-term brain fog even after their initial symptoms disappear. 

Researchers believe neurological symptoms like brain fog occur because of a process called central sensitization. This process occurs during PTLDS and affects the central nervous system (CNS) which is made up of the brain and spinal cord. Central sensitization of the CNS can make you feel extra sensitive to pain, more fatigued, and less focused. 

Why You Might Experience Brain Fog 

While many people with Lyme disease report experiencing brain fog, the connection between Lyme disease and brain fog is complex and remains poorly understood. At this time, researchers are unsure how Lyme disease can directly cause brain fog. However, research on brain fog may help scientists better understand the relationship. 

The COVID-19 pandemic led to an increase in studies about brain fog because some people who tested positive for COVID developed brain fog. Based on these studies, some researchers believe there may be two possible causes of brain fog:  

  1. Blood-brain barrier entry: Researchers believe there is a possibility that B. burgdorferi and B. mayonii may have the ability to pass through the blood-brain barrier. The blood-brain barrier is a system of tissue and blood vessels that keeps harmful substances in the blood from entering the brain. If the group of bacteria that causes Lyme disease can get into the brain, it can disrupt normal brain activity, which may result in brain fog.
  2. Increased cytokines: When a person has Lyme disease, the body produces cytokines, small proteins that promote inflammation in the body. If the body has too many cytokines, it leads to a “cytokine storm.” Scientists believe that as Lyme disease progresses, bacteria enter the blood-brain barrier and produce more cytokines, leading to inflammation and brain fog.

These findings may influence Lyme disease researchers to further investigate the effects of brain functioning in people with Lyme disease.


Early diagnosis and treatment are important to prevent uncomfortable symptoms associated with the progression of Lyme disease, such as brain fog. The most commonly prescribed medications for the disease include oral antibiotics (e.g., Monodox, Amoxil, Ceftin, and Rocephin) that are administered intravenously (through an IV). Although most cases of Lyme disease can be resolved through a two to four-week course of oral antibiotics, you may need additional treatment time if your symptoms do not improve or worsen.

If symptoms persist, your healthcare provider may look into other problems that may have emerged due to the disease itself or because of an unrelated health issue. Additional treatments and/or recommendations for symptom management may include:

  • Taking vitamin D to reduce inflammation
  • Getting seven to eight hours of sleep per night 
  • Exercising regularly to release endorphins, chemicals that can improve memory and learning
  • Avoiding alcoholic beverages, which can further impair memory and focus 
  • Reducing stress 

Generally, increased stress is thought to worsen symptoms in people with chronic illnesses. Managing stress can look like practicing meditation, spending time with loved ones, or seeking mental health support. 

When to See a Healthcare Provider

If you notice a tick bite on your body, have flu-like symptoms, or live in an area where ticks are common, you may want to reach out to your healthcare provider. You should still seek medical care even If your symptoms go away. Left untreated, the Lyme disease-causing bacteria may spread to different parts of the body and lead to more severe symptoms. Although Lyme disease is rarely fatal, early diagnosis and treatment can prevent you from developing serious symptoms and lead to a better quality of life with the disease. 

A Quick Review

Tick-borne illnesses like Lyme disease are on the rise in the U.S. Lyme disease is caused by tick bites, which can induce flu-like symptoms such as fatigue, fever, and muscle pain. Those with Lyme disease may also experience a neurological impairment called brain fog, which can make you feel drowsy, less focused, and disoriented. 

Brain fog typically occurs if someone with Lyme disease has post-treatment Lyme disease syndrome (PTLDS), a long-term condition that develops after being treated for Lyme disease. While many people with PTLDS report brain fog, researchers are still investigating how Lyme disease can cause brain fog. 

If you suspect you have Lyme disease symptoms, it is important to reach out to a healthcare provider early to receive a diagnosis, get proper treatment, and learn how to manage symptoms. 

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