Lyme disease is an infectious condition transmitted to humans through the bite of an infected black-legged tick. It is caused by the spiral-shaped bacteria Borrelia burgdorferi, which travels throughout the bloodstream and affects multiple organ systems. While Lyme disease is commonly associated with joint pain and neurological issues, it can cause a wide range of digestive problems. The bacteria and the resulting immune response interfere with the normal function of the gastrointestinal tract.
How Lyme Disease Affects the Digestive System
The Borrelia bacteria impact the gut through systemic inflammation and damage to the nervous system. The presence of the spirochetes triggers a body-wide immune response that targets the lining of the gastrointestinal (GI) tract. This chronic inflammation irritates the intestinal barrier, leading to increased permeability, often referred to as “leaky gut.” This inflammatory cascade creates a hostile environment within the digestive system.
The second mechanism involves the nervous system, as the infection can lead to autonomic neuropathy. This is damage to the nerves that automatically control bodily functions, including gut motility. These nerves regulate peristalsis, the rhythmic muscular contractions that move food through the GI tract. When this process is impaired, the muscles of the digestive tract can become severely slowed or paralyzed, sometimes referred to as “Bell’s palsy of the gut.”
Common Digestive Symptoms Linked to Lyme
The underlying inflammation and nerve dysfunction translate into a variety of symptoms. Unexplained abdominal pain and chronic nausea are frequently reported, sometimes accompanied by vomiting, especially in acute stages. Disrupted motility can manifest as chronic constipation, diarrhea, or alternating between the two.
Functional motility disorders are common, as the slowed movement of contents through the small intestine favors bacterial overgrowth. This is known as Small Intestinal Bacterial Overgrowth (SIBO), which produces symptoms like gas, bloating, and discomfort. Inflammation can also extend to other digestive organs, with some patients showing signs of liver inflammation (hepatitis). Severe acid reflux and heartburn can also arise from GI distress and nerve involvement.
Why Diagnosis is Difficult
Attributing chronic digestive problems to Lyme disease presents a significant challenge. The symptoms of Lyme-related gastrointestinal distress frequently overlap with those of common functional disorders, leading to a high rate of misdiagnosis. Conditions like Irritable Bowel Syndrome (IBS), SIBO, and chronic gastritis share many of the same complaints, such as persistent abdominal pain and altered bowel habits. Physicians may quickly label a patient with a functional GI disorder without fully exploring the infectious root cause.
Standard diagnostic tests for Lyme disease, such as the ELISA and Western Blot, can also complicate the clinical picture. These tests may not always be sensitive enough to detect the infection, leading to false negative results that dismiss Lyme as a possibility. Even when a Lyme diagnosis is confirmed, the severity of the GI symptoms does not always correlate directly with the standard test results, making it difficult to link the infection to the patient’s gut complaints. This diagnostic difficulty often results in patients being told their symptoms are psychosomatic, such as “just anxiety” or stress-related IBS.
The Impact of Lyme Treatment on Gut Health
The necessary treatment for Lyme disease often involves long courses of high-dose antibiotics, which introduces a challenge to gut health. Antibiotics eliminate Borrelia but also destroy beneficial gut microbes. This imbalance, known as dysbiosis, can persist long after treatment and contributes to lasting digestive symptoms.
The loss of commensal bacteria is disruptive, notably those that produce short-chain fatty acids like butyrate, which is important for maintaining the integrity of the gut lining. This antibiotic-induced dysbiosis can create a favorable environment for the overgrowth of opportunistic pathogens, such as yeast (Candida), and increase the risk of severe infections like Clostridioides difficile. Studies have identified a distinct microbiome signature in post-treatment Lyme patients, characterized by changes like a decrease in the Bacteroides genus and an increase in Blautia. These post-treatment effects can result in nutrient malabsorption and prolonged diarrhea.